Saturday, May 14, 2022

New Smartphone-Powered Microchip Opens the Door for Faster, Cheaper At-Home Medical Testing

A University of Minnesota Twin Cities research team has developed a new microfluidic chip for diagnosing diseases that uses a minimal number of components and can be powered wirelessly by a smartphone. The innovation opens the door for faster and more affordable at-home medical testing.

The researchers' paper is published in Nature Communications, a peer-reviewed, open access, scientific journal published by Nature Research. Researchers are also working to commercialize the technology.

Microfluidics involves the study and manipulation of liquids at a very small scale. One of the most popular applications in the field is developing "lab-on-a-chip" technology, or the ability to create devices that can diagnose diseases from a very small biological sample, blood or urine, for example.

Scientists already have portable devices for diagnosing some conditions-;rapid COVID-19 antigen tests, for one. However, a big roadblock to engineering more sophisticated diagnostic chips that could, for example, identify the specific strain of COVID-19 or measure biomarkers like glucose or cholesterol, is the fact that they need so many moving parts.

Chips like these would require materials to seal the liquid inside, pumps and tubing to manipulate the liquid, and wires to activate those pumps-;all materials that are difficult to scale down to the micro level. Researchers at the University of Minnesota Twin Cities were able to create a microfluidic device that functions without all of those bulky components.

Many lab-on-a-chip technologies work by moving liquid droplets across a microchip to detect the virus pathogens or bacteria inside the sample. The University of Minnesota researchers' solution was inspired by a peculiar real-world phenomenon with which wine drinkers will be familiar-;the "legs," or long droplets that form inside a wine bottle due to surface tension caused by the evaporation of alcohol.

Using a technique pioneered by Oh's lab in the early 2010s, the researchers placed tiny electrodes very close together on a 2 cm by 2 cm chip, which generate strong electric fields that pull droplets across the chip and create a similar "leg" of liquid to detect the molecules within.

Because the electrodes are placed so closely together (with only 10 nanometers of space between), the resulting electric field is so strong that the chip only needs less than a volt of electricity to function. This incredibly low voltage required allowed the researchers to activate the diagnostic chip using near-field communication signals from a smartphone, the same technology used for contactless payment in stores.

This is the first time researchers have been able to use a smartphone to wirelessly activate narrow channels without microfluidic structures, paving the way for cheaper, more accessible at-home diagnostic devices.

"This is a very exciting, new concept," said Christopher Ertsgaard, lead author of the study and a recent CSE alumnus (ECE Ph.D. '20). "During this pandemic, I think everyone has realized the importance of at-home, rapid, point-of-care diagnostics. And there are technologies available, but we need faster and more sensitive techniques. With scaling and high-density manufacturing, we can bring these sophisticated technologies to at-home diagnostics at a more affordable cost."

Oh's lab is working with Minnesota startup company GRIP Molecular Technologies, which manufactures at-home diagnostic devices, to commercialize the microchip platform. The chip is designed to have broad applications for detecting viruses, pathogens, bacteria, and other biomarkers in liquid samples.

"To be commercially successful, in-home diagnostics must be low-cost and easy-to-use," said Bruce Batten, founder and president of GRIP Molecular Technologies. "Low voltage fluid movement, such as what Professor Oh's team has achieved, enables us to meet both of those requirements. GRIP has had the good fortune to collaborate with the University of Minnesota on the development of our technology platform. Linking basic and translational research is crucial to developing a pipeline of innovative, transformational products."

In addition to Oh and Ertsgaard, the research team included University of Minnesota Department of Electrical and Computer Engineering alumni Daniel Klemme (Ph.D. '19) and Daehan Yoo (Ph.D. '16) and Ph.D. student Peter Christenson.

This research was supported by the National Science Foundation (NSF). Oh received support from the Sanford P. Bordeau Endowed Chair at the University of Minnesota and the McKnight University Professorship. Device fabrication was performed in the Minnesota Nano Center at the University of Minnesota, which is supported by NSF through the National Nanotechnology Coordinated Infrastructure (NNCI).

Source: University of Minnesota

Journal reference: Ertsgaard, C. T., et al. (2022) Open-channel microfluidics via resonant wireless power transfer. Nature Communications.  doi.org/10.1038/s41467-022-29405-2.

New Rapid Virus Test uses Gold Particles and is 150 Times More Accurate than Standard Tests

University of Texas at Dallas researchers have developed a rapid virus test using gold particles and lasers that promises to deliver results as accurate as lab tests in a fraction of the time.

The technology, called digital plasmonic nanobubble detection—or Diamond for short—is 150 times more accurate than standard rapid tests, according to a study published in Nature Communications last month. Its accuracy is comparable to polymerase chain reaction (PCR) tests, which take hours to perform.

The team of UTD scientists that authored the study, led by associate professor of mechanical engineering Dr. Zhenpeng Qin, tested Diamond against respiratory syncytial virus, although the researchers say the technology can be used to detect other prominent viruses, like COVID-19 and influenza.

"For the [PCR] COVID test, we drive through the pharmacy and give the sample. Getting the sample tested usually takes two to four hours before we get the results," said Haihang Ye, a UTD research associate in mechanical engineering. "Our technology can reduce the sample testing time to 30 minutes, but the sensitivity can be as good as those molecular tests."

Faster, cheaper and more effective virus tests are in high demand as the U.S. shifts into a new normal in the coronavirus pandemic. Though case counts are near all-time lows in North Texas, the highly contagious BA.2 variant continues to spread locally and across the country.

The cost of a COVID-19 test varies widely depending on location and type of test. A study of the largest hospitals in every state done by the Peterson Center of Healthcare and Kaiser Family Foundation Health System Tracker found coronavirus test prices ranged anywhere from $20 to more than $1,400. Only 3% of the hospitals surveyed listed testing prices below $50.

A Diamond test, which Ye said can be produced for around $15, mixes a patient sample from a nasal swab with gold nanoparticles attached to antibodies for the virus being tested. The antibodies, marked by the gold nanoparticles, then bind with proteins on the virus' surface if the virus is present in the sample.

Researchers then inject the sample mixed with labeled antibodies into a narrow tube mounted on a glass slide. As the liquid passes through the tube, it's hit by the beams of two lasers, one of which activates the gold nanoparticles, causing them to expand.

If the expansion is strong enough, the nanoparticle will boil the water around it and create vapor bubbles. Large nanobubbles mean the virus is present in the sample.

"If there's no virus, there will be a tiny nanobubble signal from the particle only so we can differentiate the sample's status," said Yaning Liu, a UTD mechanical engineering doctoral student and co-first author of the Diamond study.



Diamond is the product of years of research and millions of dollars in grant funding, including $2.5 million in grants from the National Institute of Allergy and Infectious Diseases and a $293,000 grant from the Department of Defense's Congressionally Directed Medical Research Programs.

To test different viruses using the technology, all researchers need to do is change the associated antibodies, Ye said. Though Diamond has the potential to expand testing options for a number of viruses, it requires researchers to know what they're testing for.

"One of the challenges with the current tests is that providers have to kind of have an idea of what they're looking for," said Elitza Theel, associate professor of laboratory medicine and pathology at the Mayo Clinic in Rochester, Minn.

A less-targeted approach using a technology called metagenomic next-generation sequencing allows scientists to sequence all of the genetic material in a sample to identify which infectious pathogens are present. The technology is already in use, but the process is expensive and takes days to return results, Theel said.

"It's not really helpful in the immediate acute setting," she said.

While Diamond must be approved by the Food and Drug Administration before it can be used publicly, the scientists behind the technology launched a company called Avsana Labs to hopefully commercialize it. Qin serves as president of the company, which was created through UTD's Venture Development Center.

Just last week, another North Texas company had its COVID-19 test approved by the FDA. Frisco-based InspectIR Systems invented a breathalyzer apparatus, the first coronavirus test of its kind to get federal approval, that can yield results in less than three minutes.

Yaning Liu et al, Digital plasmonic nanobubble detection for rapid and ultrasensitive virus diagnostics, Nature Communications (2022). DOI: 10.1038/s41467-022-29025-w

Rapid Method Shown to Detect Infection in Cystic Fibrosis

Rapid method shown to detect infection in cystic fibrosis: Southampton researchers have demonstrated a quick and accurate method to diagnose bacterial infections. The technique has the potential to detect infections in cystic fibrosis patients in minutes rather than days.

In future, the simple analysis could be performed on hospital wards to deliver faster and more effective treatment.

The approach could also be expanded to target a variety of diseases and counter anti-microbial resistance.

Cystic fibrosis is an inherited condition that causes sticky mucus to build up in the lungs and digestive system. This causes lung infections and problems with digesting food.

It affects around 1 in every 10,000 births in the UK.

Treatments are available to help reduce the problems caused by the condition. Yet recurring infections still dramatically reduce the quality and length of life.

The current methods for diagnosing immediate (acute) and longer-term (chronic) infections are complex and time-consuming in the laboratory. For biofilm infections, it can take days from collecting and processing a patient’s sample to achieving a result. This delays effective treatments and impacts patient outcomes.

A multi-disciplinary team from the University of Southampton and University Hospital Southampton set out to develop a diagnostic tool that would be rapid, accurate and simple-to-use for doctors.

They have developed a new chemical analysis technique called multi-excitation Raman spectroscopy. This non-invasive method emits a scattering of multiple colours of light into a patient’s sample.

Prof Sumeet Mahajan, Head of Chemical Biology and the Associate Director of Institute for Life Sciences at the University of Southampton, explained:

“When light is applied to a sample’s molecules they can vibrate which helps us understand their characteristics. By using different colours of light, a different set of such vibrations can be triggered meaning we can get more information about their composition than previously possible.

“This then allows ‘finger-printing’ that can be used to identify the properties of the pathogens that cause cystic fibrosis. In many current techniques, a reagent needs to be added to a sample or a tag needs to be attached to the molecules of interest to analyse their composition. This is not required under this new approach which uses natural properties of the molecules to analyse them.”

Professor Mahajan continued: “Our new Raman spectroscopy based method offers many advantages over resource-intensive, culture-based methods, allowing rapid and label-free analysis. It is reagentless and avoids complex sample-preparation steps with sophisticated equipment. Here, we have developed a method that is highly accurate yet rapid and neither requires nanoscale materials for enhancing signals nor fluorophores for detection.”

Long term infections in the lungs of people with cystic fibrosis are extremely hard to treat . There is evidence that the Pseudomonas aeruginosa bacteria exists as biofilms in the body, protecting the bacteria from antibiotic action and driving antimicrobial resistance. This increases the urgency for rapid and effective treatment.

The Southampton research, published in Analytical Chemistry, showed 99.75% accuracy at identifying Pseudomonas aeruginosa and Staphylococcus aureus across all studied strains. This included 100% accuracy for drug-sensitive and drug-resistant Staphylococcus aureus.

The project drew together expertise from the National Institute for Health and Care Research (NIHR) Southampton Biomedical Research Centre (BRC) and Southampton Clinical Research Facility (CRF), the National Biofilms Innovation Centre (NBIC), together with the University of Southampton’s School of Chemistry and Institute for Life Sciences (IfLS). It was led by Professor Mahajan, Professor Jeremy Webb and Professor Saul Faust.

Prof Faust, Director of NIHR Southampton CRF, said: “Our study demonstrates an important step toward a rapid and reagentless diagnostic tool requiring only simple or routine sample preparation.

“Such a platform could also prove useful in a variety of other disease areas and help address the mounting challenge of anti-microbial resistance.”

Saturday, March 5, 2022

'Fingerprint' Machine Learning Technique Identifies Different Bacteria in Seconds​

Bacterial identification can take hours and sometimes longer, valuable time when diagnosing infections and choosing acceptable therapies. There could also be a faster, extra correct course of in response to researchers at KAIST. By educating a deep studying algorithm to establish the “fingerprint” spectra of the molecular parts of assorted micro organism, the researchers might classify numerous micro organism in several media with accuracies of as much as 98%.

Their outcomes have been made obtainable on-line on Jan. 18 in Biosensors and Bioelectronics, forward of publication within the journal’s April subject.

Micro organism-induced sicknesses, these brought on by direct bacterial an infection or by publicity to bacterial toxins, can induce painful signs and even result in dying, so the speedy detection of micro organism is essential to stop the consumption of contaminated meals and to diagnose infections from scientific samples, akin to urine. “By utilizing surface-enhanced Raman spectroscopy (SERS) evaluation boosted with a newly proposed deep learning model, we demonstrated a markedly easy, quick, and efficient path to classify the indicators of two widespread micro organism and their resident media with none separation procedures,” mentioned Professor Sungho Jo from the College of Computing.

Raman spectroscopy sends gentle by way of a pattern to see the way it scatters. The outcomes reveal structural details about the pattern—the spectral fingerprint—permitting researchers to establish its molecules. The surface-enhanced model locations pattern cells on noble steel nanostructures that assist amplify the pattern’s indicators.

Nevertheless, it’s difficult to acquire constant and clear spectra of micro organism on account of quite a few overlapping peak sources, akin to proteins in cell partitions. “Furthermore, sturdy indicators of surrounding media are additionally enhanced to overwhelm goal indicators, requiring time-consuming and tedious bacterial separation steps,” mentioned Professor Yeon Sik Jung from the Division of Supplies Science and Engineering.

To parse by way of the noisy indicators, the researchers applied a synthetic intelligence technique known as deep studying that may hierarchically extract sure options of the spectral info to categorise information. They particularly designed their mannequin, named the dual-branch wide-kernel community (DualWKNet), to effectively be taught the correlation between spectral options. Such a capability is crucial for analyzing one-dimensional spectral information, in response to Professor Jo.

Schematics of the general process of Raman data collection and analysis where a single spectrum is attained from a single cell and classified via deep learning

“Regardless of having interfering indicators or noise from the media, which make the overall shapes of various bacterial spectra and their residing media indicators look comparable, excessive classification accuracies of bacterial sorts and their media have been achieved,” Professor Jo mentioned, explaining that DualWKNet allowed the crew to establish key peaks in every class that have been nearly indiscernible in particular person spectra, enhancing the classification accuracies. “In the end, with the usage of DualWKNet changing the micro organism and media separation steps, our technique dramatically reduces evaluation time.”

The researchers plan to make use of their platform to review extra micro organism and media sorts, utilizing the knowledge to construct a coaching information library of assorted bacterial sorts in extra media to cut back the gathering and detection instances for brand new samples.

“We developed a significant common platform for speedy bacterial detection with the collaboration between SERS and deep studying,” Professor Jo mentioned. “We hope to increase the usage of our deep learning-based SERS evaluation platform to detect quite a few varieties of bacteria in extra media which can be necessary for meals or scientific evaluation, akin to blood.”

Reference

Eojin Rho et al, Separation-free bacterial identification in arbitrary media by way of deep neural network-based SERS evaluation, Biosensors and Bioelectronics (2022). 

Sunday, February 6, 2022

Simple, Inexpensive, Fast and Accurate Nano-sensors Pinpoint Infectious Diseases

A very interesting paper has been published by Arizona State University scientists that describes a design for an in-solution assay pipeline, featuring nanobody-functionalized nanoparticles for rapid, electronic detection (Nano2RED) of Ebola and COVID-19 antigens. Without requiring any fluorescent labelling, washing, or enzymatic amplification, these multivalent AuNP sensors reliably transduce antigen binding signals upon mixing into physical AuNP aggregation and sedimentation processes, displaying antigen-dependent optical extinction readily detectable by spectrometry or portable electronic circuitry.

The university has summarized the research in a review article from its news department, and is replicated below.

In recent years, deadly infectious diseases, including Ebola and COVID-19, have emerged to cause widespread human devastation. Although researchers have developed a range of sophisticated methods to detect such infections, existing diagnostics face many limitations.

In a new study, Chao Wang, a researcher at Arizona State University’s Biodesign Institute and School of Electrical, Computer & Energy Engineering, along with ASU colleagues and collaborators at the University of Washington (UW), Seattle describe a novel method for detecting viruses like Ebola virus (EBOV) and SARS CoV-2.

The technique, known as Nano2RED, is a clever twist on conventional high-accuracy tests relying on complex testing protocols and expensive readout systems. The in-solution nano-sensors (“Nano2” in the name) serve to detect disease antigens in a sample by simple mixing. The innovative Rapid and Electronic Readout process (“RED”) developed in the Wang lab delivers test results, which are detectable as a color change in the sample solution, and record the data through inexpensive semiconductor elements such as LEDs and photodetectors.

The technology represents a significant advance in the fight against infectious diseases. It can be developed and produced at very low cost, deployed within weeks or days after an outbreak, and made available for around 1 cent per test.

Compared with widely used high-accuracy lab tests, such as ELISA, Nano2RED is much easier to use. It does not require surface incubation or washing, dye labelling, or amplification, yet still provides about 10 times better sensitivity than ELISA. In addition, the use of semiconductor devices supports a highly portable digital readout system, which can be developed and produced at a cost as low as a few dollars, making it ideal not only for lab use but for clinics, home use, and remote or resource-strained locations. This approach is based on modular designs, and could potentially be used to test for any pathogen.

“This technology works not because it is complex but because it is simple,” says professor Wang. “Another unique feature is the multidisciplinary nature of biosensing. A fundamental understanding of biochemistry, fluidics, and optoelectronics helped us come up with something this ‘simple’.”

Wang is a researcher with the Biodesign Center for Molecular Design and Biomimetics at ASU. He is also a researcher with ASU’s School of Electrical, Computer and Energy Engineering; and the Center for Photonic Innovation. Dr. Liangcai Gu is the collaborator at Department of Biochemistry and Institute for Protein Design at UW, Seattle.

The research appears in the current issue of the journal Biosensors and Bioelectronics. Dr. Xiahui Chen and Md Ashif Ikbal from ASU and Dr. Shoukai Kang from UW are the first authors, and Jiawei Zuo and Yuxin Pan are the other contributing authors.

The testing bottleneck

Epidemiologists have long known the basic formula when confronting a disease outbreak. To identify cases and stop the contagion, it is necessary to develop an accurate test or assay that can identify the disease, then test early and often, to assess the rate of spread and attempt to isolate the infected.

Unfortunately, by the time a new diagnostic has been developed, manufactured, and distributed, the disease outbreak is often already widespread and challenging to contain. Further, accurate tests including PCR, (which can amplify tiny levels of pathogenic nucleic acids to measurable levels), are often expensive, labor-intensive and require sophisticated laboratory facilities.

The Ebola epidemic of 2014-2016, though largely confined to West Africa, spread with terrifying speed, causing panic and killing more than 11,000 people. The virus’ rate of lethality, one of the highest for any known pathogen, can exceed 90%, depending on disease strain. The crisis was exacerbated by a combination of inadequate surveillance systems and poor public health infrastructure.

SARS CoV-2, though less lethal than Ebola, has spread to every country on earth and has already killed more than 5.6 million people worldwide. In both disease outbreaks, diagnostic testing arrived late on the scene. Further, costly and cumbersome testing requirements have meant that far too few tests have been administered, even after their successful development.

The new study applies its innovative method to test for these two prominent diseases, as a proof of concept.

Tidal wave

A common feature in many disease outbreaks is the lightning speed with which a pathogen, having first infected a handful of people, can gather momentum, fan out in all directions and quickly overwhelm hospitals and healthcare providers. Cutting off a pathogen’s routes of transmission requires identifying and isolating sick individuals through testing, as quickly as possible.

During a pandemic like COVID-19, the sensitivity of a given diagnostic test is secondary to how often the test is given and how long it takes for results to be processed. A highly sensitive test is of limited use if it can only be given once, and results require a weeks-long turnaround. Research has shown that infection outbreaks are best controlled when testing is repeated in less than 3-day intervals and at a large scale.

Adequately preparing society for current and future outbreaks of infectious disease will require faster, cheaper, more accurate and more easily usable diagnostics.

Close affinity

The new technology can identify secreted glycoprotein (sGP), a telltale fingerprint of Ebola virus disease and the SARS-CoV-2 spike protein receptor binding domain (RBD). The technology is highly accurate, rivaling ELISA, a long-recognized gold standard technology for diagnostic testing.

The basic idea of such diagnostics, known as immunoassays, is simple: a sample of blood (or other biological fluid) is applied to the assay, which is adorned with antibodies. When antibodies recognize the presence of a corresponding disease antigen in the sample, they bind with it, producing a positive test result. In the ELISA test, the disease antigen needs to be immobilized on a flat surface.

Nano2RED also relies on binding affinity for positive diagnosis but instead uses floating gold nanoparticles for readout. Unlike ELISA, Nano2RED can be developed from scratch in roughly 10 days and theoretically applicable for any pathogen, providing vitally important early surveillance in the case of a disease outbreak. It can deliver test results in 15-20 minutes and may be administered at an estimated cost of a penny per test. In the current study, the new test was shown to detect Ebola’s sGP in serum with a sensitivity roughly 10 times better than ELISA.

Sensing danger

The accompanying graphic shows how the method works: The first step is to produce a very large library containing over a billion random amino acid sequences known as nanobodies, that can act as synthetic antibodies, able to bind with target disease antigens. This vast library of nanobodies is then successively screened against the antigen in question, for example sGP in the case of Ebola. Only those nanobodies that show strong binding affinity for the antigen are used for sensing.


Next, the selected nanobodies are affixed to gold nanoparticles that will act as probes to identify and bind with antigens present in a blood sample. In the study, a pair of two high affinity nanobodies were selected and attached to gold nanoparticles. This approach improves both the sensitivity and specificity of the test.

The key innovation of Nano2RED is the way the antigen detection is registered. As disease antigens in the sample are recognized by the nanobodies, they bind together, forming clusters of bound nanobody and antigen, like islands of algae floating on the sea surface. “Basically, an antigen works like superglue to bring the nanoparticle together,” Wang says. 

A “golden” opportunity in the fight against infectious disease

The gold nanoparticles provide a stable platform to hold the nanobodies in place.  Once enough binding has taken place, the bound clusters begin to sink to the bottom of the vessel. This can be detected with the naked eye in the form of a color change. The solution becomes lighter in color as the gold-nanoparticle-carried antigen-antibody clusters precipitate out, signaling detection of the pathogen.

While full precipitation of nanoparticle clusters leading to a test result can normally take several hours, the process can be sped up by centrifuging the sample, which eliminates the wait time for precipitation. In this case, just 15-20 minutes are sufficient for a result. “Of course, the gold nanoparticles are heavy, and that helps quick sedimentation, too.” Wang added.

Gold nanoparticles also work to display color, not yellow but red here, by absorbing light from a narrow spectral range. This absorbance feature allowed the Wang lab to invent  a tiny, inexpensive device that converts this color change into an electrical signal, using color-matching semiconductor LEDs and photodetectors. Such instruments produce a rapid and accurate readout of assay results, whose limits of detection are comparable to or better than costly lab-based spectroscopy methods.

The test also delivers quantitative results based on amount of antigen detected. This could be vitally useful for estimating disease severity as well as time elapsed since the infection event. In the future, the test results can be digitized by circuits and conveniently transmitted via internet to anywhere in the world for data analysis and further scrutiny, which could be important to government policy decision-making processes and timely interruption of the transmission.

Nano2RED requires only a tiny blood sample, typically around 20 microliters. “This also makes gold inexpensive in our case, because the mount we need is so tiny.” Wang said. Unlike conventional methods, Nano2RED is also very simple to use with minimal training involved for healthcare personnel. It does not require any time-consuming and expensive incubation, washing, fluorescent labeling or amplification.

Future research will help improve the assay’s limits of detection even further and modify its detection capacities to include virion particles, extracellular vesicles, small molecules, and nucleic acids. “There is certainly still a lot to explore” Wang added, “but we so far have a happy marriage between engineering disciplines and biology. And that is what we will continue to work on.”

This research was supported by the National Science Foundation and National Institutes of Health.

Source: Arizona State University

Saturday, January 29, 2022

Magnetic Nanoparticles for SARS-CoV-2 and Other Virus Detection Systems

A recent article by Dr. Ramya Dwivedi, Ph.D. (National Chemical Laboratories in Pune, India) provides insights into functionalizing nanoparticles with different molecules of biological interest, and studying the reaction system and establishing useful applications. 

In light of the current coronavirus disease 2019 (COVID-19) pandemic caused by the emergence of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), researchers have become increasingly interested in novel technologies that could help quickly diagnose viral infections.

In a recent Talanta review article, researchers discuss the contributions that have been provided by magnetic nanoparticles for the molecular diagnosis of human viruses.

Introduction

Nanotechnology-based techniques are adaptable and reliable in detecting diseases caused by viruses. Solid lipid nanoparticles, liposomes, inorganic nanoparticles, and polymeric nanoparticles are some of the most widely used advanced materials that are used in nanotechnology.

Nanoparticles allow researchers to conduct analyses at both cellular- and molecular-scale, which has supported their crucial role in various diagnostic advancements. For example, nanoprobes designed to recognize specific molecules have helped identify targets, even when present at low concentrations.

The present review focuses on the role of magnetic nanoparticles (MNPs) in identifying viruses, wherein the researchers provide insight into novel diagnostic methods that overcome many of the limitations associated with conventional diagnostic approaches.

Limitations of conventional systems

The technique used to diagnose the presence of a specific virus has often been specific to each virus; however, one of the most common assays includes the reverse-transcriptase polymerase chain reaction (RT-PCR). In addition to being the gold standard for diagnosing COVID-19, RT-PCR has also been used to detect the Marburg virus, Ebola virus, human immunodeficiency virus (HIV), hantavirus (HPS), influenza virus, and dengue virus.

In addition to RT-PCR, enzyme-linked immunosorbent assays, rapid antigen testing, immunofluorescence assays, and other forms of serological testing have also been used for conventional virus detection purposes.

Despite their clinical utility, many of these conventional techniques are associated with several limitations including the need for mass-testing kits, robust sensitivity capabilities, length completion requirements, and experienced personnel. For example, some of the requirements for RT-PCR in the diagnosis of COVID-19 include the refined extraction and accurate estimation of nucleic acids, which can lead to skewed results when performed by untrained personnel.  

Furthermore, despite the availability of marketable kits that are easy to use, despite their high costs, and typically yield better ribonucleic acid (RNA) quality, accessibility to these kits during the pandemic was affected as a result of supply chain interruptions.

Taken together, there is a pronounced motivation to advance alternative diagnostic approaches that address these challenges, while also eliminating the hazard of handling live viruses and its associated biological safety requirements.

Nanoparticles in viral diagnosis

Many nanomaterials including MNPs, quantum dots (QDs), silicon nanowires (SiNWs), virus-like particles (VLPs), graphene, inorganic nanoparticles, liposomes, nanoparticles of self-assembled protein, polymers, and metal, silica nanospheres, as well as carbon nanotubes (CNTs), nanostructured surfaces and films are utilized for viral diagnostic purposes. Many of these nanomaterials are associated with unique properties including bioavailability, optimum tunable size, charge, shape, biodegradability, high surface plasmon resonance (SRP), photon exchange, superparamagnetism, luminescence, biocompatibility, immunocompatibility, and tolerability, all of which can be attractive characteristics for viral detection applications.

The ability to manipulate the surface of nanomaterials using functionalization chemistry further supports the utility of these materials useful for both diagnostic and therapeutic purposes.

Importantly, nano-based detection systems, along with extraction, offer several advantages as compared to conventional diagnostic approaches. These systems allow for the easy, rapid, highly sensitive, and label-free detection of viruses that will undoubtedly advance point-of-care (POC) nanodiagnostics in clinical practice.

MNPs and virus diagnosis

Among the numerous inorganic nanoparticles including gold, silver, and iron oxide that have been widely studied over the past several years, MNPs are often utilized for nucleic acid extraction, purification, and detection.

Some of the advantages associated with MNPs for these applications include their ability to magnetically control their accumulation, superparamagnetic behavior, inexpensive preparation, quick isolation inside buffer solutions, and sensitivity for signal detection of the signal. Taken together, these properties of MNPs allow for the purification, pre-concentration, and separation of nucleic acids to be completed quickly, all the while retaining specificity during the viral detection process.

MNPs also play an important role in real-time detection systems when combined with a fluorescent or chemiluminescent probe. For these applications, the morphology, functionalization, surface coating, and properties of MNPs are highly tunable, thereby allowing researchers to attach a wide range of groups to MNPs to increase their chemical functionality, constancy, wettability, and bonding adaptability for numerous applications.

MNPs in the diagnosis of COVID-19

Zinc ferrite (ZNF) MNPs functionalized by carboxylic group polymers, as well as multifunctional chitosan-coated lithium zinc ferrite MNPs integrated with graphene oxide MNPs (CHLZFO-GO MNC), have been used for the extraction of RNA to ultimately detect SARS-CoV-2 in patient samples.

By extracting viral RNA through these methods before the RT-PCR testing, researchers can effectively reduce the risk of false negatives. This type of advanced approach to RNA isolation from nasal swabs can also expand the ability to rapidly diagnose COVID-19 at much larger scales.

MNPs have also been studied for their ability to enhance the sensitivity of biosensing devices for the rapid detection of the SARS-CoV-2 spike protein and single-stranded RNA (ssRNA) obtained from biological samples including blood, urine, and serum. One such example is the giant magnetoresistive (GMR) biosensing device, which has the potential to provide quick and consistent detection of pathogens like SARS-CoV-2 to reduce the uncertainty during viral incubation periods.

Another biosensing application of MNPs for SARS-CoV-2 diagnostic purposes includes the use of functionalized MNPs, followed by a measurement of their magnetic response in an AC magnetic field. To this end, functionalized MNPs were used as sensors to detect mimic SARS-CoV-2 containing spike proteins that are bound with polystyrene beads, which allowed for a quick detection time that does not compromise on its sensitivity for SARS-CoV-2 detection.

To resolve some of the challenges associated with the labor-intensive requirements of current molecular analytical processes, MNPs that have been functionalized with poly (amino ester) bonded to carboxyl groups (pcMNPs) have been studied for RNA extraction techniques.

The complex of pcMNPs with RNA samples can immediately be used for RT-PCR reactions, thereby reducing the time constraints of this process to about 20 minutes. In addition to being a more rapid approach to RT-PCR analysis for COVID-19 diagnoses, this approach utilizing pcMNPs also provides a 10-copy sensitivity.  

Conclusions

The present review provides insights into MNP strategies that have been designed for specific and non-specific viral diagnostic approaches. Importantly, various studies have looked to how MNPs can be incorporated into each step of the viral diagnosis process including extraction and purification to enrichment and detection of pathogens.

Source: https://www.news-medical.net/ 

Friday, January 28, 2022

Scientists Develop Non-invasive Sensor that Changes Color if a Wound Becomes Infected

Scientists at Queen’s University Belfast have invented a tiny indicator that changes colour if a patient’s wound shows early signs of infection.

The non-invasive indicator, which is around the same size as one of our fingertips, is the first of its kind. It does not make any contact with the wound but detects the beginnings of infection by sniffing the air above it.

It can be added to already existing bandages and allows infections to be detected without taking off the dressing – something which can inhibit the healing process and increase the likelihood of wound infection.

It is estimated that around 1 to 2 per cent of people in developed countries will experience a chronic wound in their lifetime and in the UK £3.2 billion is spent each year treating the problem.

Professor Andrew Mills from the School of Chemistry and Chemical Engineering at Queen’s has been leading the project, alongside colleagues from the School of Pharmacy and School of Electronics, Electrical Engineering and Computer Science. The project was funded by the Engineering and Physical Research Council, which is part of UK Research and Innovation. The research findings have been published in the Royal Society of Chemistry’s ChemComm journal.

“Usually if a patient has a wound, especially a chronic wound, a nurse or doctor will check for infection every two to three days by removing the dressing. Changing a dressing can be unnecessary, painful and an infection risk.  All of this could be avoided with our indicator, saving time, money and pain.”

Explaining how the indicator works, Professor Mills says: “If infection is starting in a wound, there is often a sudden growth of aerobic microbiological species and as they grow they generate carbon dioxide. 

“Our indicator detects this rise in carbon dioxide causing the dot to change colour, flagging the infection in its very early stages before it actually takes hold and overwhelms the patient’s immune system. This means it can be treated quickly, avoiding unnecessary pain for the patient and significantly reducing the possible need for hospitalisation.”

Professor Brendan Gilmore from the School of Pharmacy at Queen’s says: “This sensor can provide an early warning of infection before it has progressed to a chronic, persistent colonisation of the wound by microorganisms which are by then much more difficult to treat effectively with antibiotics. 

“The sensors respond quickly to the presence of infection, and allow healthcare providers to make informed decisions about managing the wound, including whether or not to use antibiotics. Inappropriate antibiotic use is known to drive the emergence of antibiotic resistance. Crucially, these sensors can tell us whether or not the intervention has worked in killing the microorganisms which caused these infections.”

The project is entering the next phase where an app will be developed so that the patient will be alerted if there is an infection. The same information would also be sent to the patient’s nurse or doctor and be used to inform treatment plans.

Professor Mills says: “We are very pleased to now have our research findings published and to be able to offer a simple, inexpensive, non-invasive way to monitor the progress of healing wounds. We are currently in discussions with industry in how to take this forward and we hope to run clinical trials soon."

Source: SelectScience