Rapid and Accurate Diagnosis of the Respiratory Disease Pertussis on a Point-of-Care Biochip

Microfluidic point-of-care testing for the detection of Bordetella pertussis: A mini-review

Bordetella pertussis is a bacterial pathogen responsible for pertussis, which is a highly contagious respiratory disease. Despite the relatively high vaccination coverage, pertussis is considered a reemerging disease that necessitates enhanced strategies for identification, prevention, and control. The diagnosis of pertussis typically involves a combination of clinical evaluation, laboratory tests, and a thorough medical history. The current technologies for pertussis diagnosis have their own limitations, prompting the exploration of alternative diagnostic approaches that offer enhanced sensitivity, specificity, and speed. Microfluidic technology is considered a very promising tool for the diagnosis of infectious diseases, as it offers more rapid and accurate outputs. It allows point-of-care testing (POCT) at or near the patient site, which can be critical, especially for an outbreak or pandemic. In this paper, current pertussis diagnostic tools with their limitations were discussed, and microfluidic approaches for the diagnosis of pertussis were highlighted.

Bordetella holmesii: Causative agent of pertussis

Bordetella holmesii is a bacterium recently recognized in 1995. It is a gram-negative coccobacillus that can cause pertussis-like symptoms in humans as well as invasive infections. It is often confused with Bordetella pertussis because routine diagnostic tests for whooping cough are not species-specific. The prevalence of B. holmesii as a cause of pertussis has increased in several countries. Therefore, B. holmesii assays are important for determining the epidemiology of pertussis, for the choice of an effective treatment, and for detecting vaccination failures.

Microfluidic systems for infectious disease diagnostics

Microorganisms, encompassing both uni- and multicellular entities, exhibit remarkable diversity as omnipresent life forms in nature. They play a pivotal role by supplying essential components for sustaining biological processes across diverse ecosystems, including higher host organisms. The complex interactions within the human gut microbiota are crucial for metabolic functions, immune responses, and biochemical signalling, particularly through the gut-brain axis. Viruses also play important roles in biological processes, for example by increasing genetic diversity through horizontal gene transfer when replicating inside living cells. On the other hand, infection of the human body by microbiological agents may lead to severe physiological disorders and diseases. Infectious diseases pose a significant burden on global healthcare systems, characterized by substantial variations in the epidemiological landscape. Fast spreading antibiotic resistance or uncontrolled outbreaks of communicable diseases are major challenges at present. Furthermore, delivering field-proven point-of-care diagnostic tools to the most severely affected populations in low-resource settings is particularly important and challenging. New paradigms and technological approaches enabling rapid and informed disease management need to be implemented. In this respect, infectious disease diagnostics taking advantage of microfluidic systems combined with integrated biosensor-based pathogen detection offers a host of innovative and promising solutions. In this review, we aim to outline recent activities and progress in the development of microfluidic diagnostic tools. Our literature research mainly covers the last 5 years. We will follow a classification scheme based on the human body systems primarily involved at the clinical level or on specific pathogen transmission modes. Important diseases, such as tuberculosis and malaria, will be addressed more extensively.

Portable in situ temperature-dependent spectroscopy on a low-cost microfluidic platform integrated with a battery-powered thermofoil heater

A low-cost microfluidic platform integrated with a flexible heater was developed for in situ temperature-dependent spectroscopic measurement at the point of care. After verifying the system by comparing on-chip spectroscopic measurement of methylene blue with the conventional spectroscopy, we demonstrated its applications in temperature-dependent absorption spectroscopy of a model biomolecule, curcumin. The system is portable, battery-powered and requires ultra-low volumes of analytes, which is highly suitable for point-of-care characterization.

Mid-infrared silicon metasurfaces for near-field enhancement of molecular fingerprints

Mid-infrared dielectric metasurfaces are promising fundamental building blocks for integrated sensing with high sensitivity, compositional selectivity, and low loss. We have designed and fabricated a silicon metasurface with resonance properties in the 4∼5 µm mid-infrared region and a volume enhancement of up to 9 times. Benchmark FTIR characterizations of solutions of tungsten hexacarbonyl molecules showed a detection limit of 1 mg/mL without the usage of surface enrichment treatment. We further rationalize the detection limit of the molecules-nanostructure open interface with volume field enhancement analysis. Our results show that mid-infrared silicon metasurfaces may be a suitable platform for potential integration with microfluidic for in vivo detection.

Information Visualisation for Antibiotic Detection Biochip Design and Testing

Biochips are engineered substrates that have different spots that change colour according to biochemical reactions. These spots can be read together to detect different analytes (such as different types of antibiotic, pathogens, or biological agents). While some chips are designed so that each spot on its own can detect a particular analyte, chip designs that use a combination of spots to detect different analytes can be more efficient and detect a larger number of analytes with a smaller number of spots. These types of chip can, however, be more difficult to design, as an efficient and effective combination of biosensors needs to be selected for the chip. These need to be able to differentiate between a range of different analytes so the values can be combined in a way that demonstrates the confidence that a particular analyte is present or not. The study described in this paper examines the potential for information visualisation to support the process of designing and reading biochips by developing and evaluating applications that allow biologists to analyse the results of experiments aimed at detecting candidate bio-sensors (to be used as biochip spots) and examining how biosensors can combine to identify different analytes. Our results demonstrate the potential of information visualisation and machine learning techniques to improve the design of biochips.

A microfluidic fully paper-based analytical device integrated with loop-mediated isothermal amplification and nano-biosensors for rapid, sensitive, and specific quantitative detection of infectious diseases

Bacterial meningitis, an infection of the membranes (meninges) and cerebrospinal fluid (CSF) surrounding the brain and spinal cord, is one of the major causes of death and disability worldwide. Higher case-fatality rates and short survival times have been reported in developing countries. Hence, a quick, straightforward, and low-cost approach is in great demand for the diagnosis of meningitis. In this research, a microfluidic fully paper-based analytical device (μFPAD) integrated with loop-mediated isothermal amplification (LAMP) and ssDNA-functionalized graphene oxide (GO) nano-biosensors was developed for the first time for a simple, rapid, low-cost, and quantitative detection of the main meningitis-causing bacteria, Neisseria meningitidis (N. meningitidis). The results can be successfully read within 1 hour with the limit of detection (LOD) of 6 DNA copies per detection zone. This paper device also offers versatile functions by providing a qualitative diagnostic analysis (i.e., a yes or no answer), confirmatory testing, and quantitative analysis. These features make the presented μFPAD capable of a simple, highly sensitive, and specific diagnosis of N. meningitis. Furthermore, this microfluidic approach has great potential in the rapid detection of a wide variety of different other pathogens in low-resource settings.

Ultrasensitive detection of acephate based on carbon quantum dot-mediated fluorescence inner filter effects

Acephate is an organophosphorus pesticide (OP) that is widely used to control insects in agricultural fields such as in vegetables and fruits. Toxic OPs can enter human and animal bodies and eventually lead to chronic or acute poisoning. However, traditional enzyme inhibition and colorimetric methods for OPs detection usually require complicated detection procedures and prolonged time and have low detection sensitivity. High-sensitivity monitoring of trace levels of acephate residues is of great significance to food safety and human health. Here, we developed a simple method for ultrasensitive quantitative detection of acephate based on the carbon quantum dot (CQD)-mediated fluorescence inner filter effect (IFE). In this method, the fluorescence from CQDs at 460 nm is quenched by 2,3-diaminophenazine (DAP) and the resulting fluorescence from DAP at 558 nm is through an IFE mechanism between CQDs and DAP, producing ratiometric responses. The ratiometric signal I558/I460 was found to exhibit a linear relationship with the concentration of acephate. The detection limit of this method was 0.052 ppb, which is far lower than the standards for acephate from China and EU in food safety administration. The ratiometric fluorescence sensor was further validated by testing spiked samples of tap water and pear, indicating its great potential for sensitive detection of trace OPs in complex matrixes of real samples.

A new fuzzy rule based multi-objective optimization method for cross-scale injection molding of protein electrophoresis microfluidic chips

Injection molding is one of the most promising technologies for the large-scale production and application of polymeric microfluidic chips. The multi-objective optimization of injection molding process for substrate and cover plate on protein electrophoresis microfluidic chip is performed to solve the problem that the forming precision is difficult to coordinate because of the cross-scale structure characteristics for chip in this paper. The innovation for this research is that an optimization approach and a detailed fuzzy rule determination method are proposed in multi-objective optimization for protein electrophoresis microfluidic chip. In more detail, firstly, according to the number and level of process parameters, the orthogonal experimental design is carried out. Then, the experiments are performed. Secondly, the grey relational analysis (GRA) approach is employed to process the response data to gain the grey relational coefficient (GRC). Thirdly, the grey fuzzy decision making method which combines triangular membership function and gaussian membership function is adopted to obtain the grey fuzzy grade (GFG). After that, the optimal scheme of process parameters was predicted by the grey fuzzy grade analysis. Finally, the superiority of Taguchi grey fuzzy decision making method are verified by comparing the results of original scheme, optimal scheme and prediction scheme. As a result, compared with the original design, the residual stress of substrate plate (RSS), residual stress of cover plate (RSC), warpage of substrate plate (WS), warpage of cover plate (WC) and replication fidelity of microchannel for substrate plate (RFM) on the prediction scheme for Taguchi grey fuzzy decision making method were reduced by 32.816%, 29.977%, 88.571%, 74.390% and 46.453%, respectively.

Immunotherapy discovery on tumor organoid-on-a-chip platforms that recapitulate the tumor microenvironment

Cancer immunotherapy has achieved remarkable success over the past decade by modulating patients' own immune systems and unleashing pre-existing immunity. However, only a minority of cancer patients across different cancer types are able to benefit from immunotherapy treatment; moreover, among those small portions of patients with response, intrinsic and acquired resistance remains a persistent challenge. Because the tumor microenvironment (TME) is well recognized to play a critical role in tumor initiation, progression, metastasis, and the suppression of the immune system and responses to immunotherapy, understanding the interactions between the TME and the immune system is a pivotal step in developing novel and efficient cancer immunotherapies. With unique features such as low reagent consumption, dynamic and precise fluid control, versatile structures and function designs, and 3D cell co-culture, microfluidic tumor organoid-on-a-chip platforms that recapitulate key factors of the TME and the immune contexture have emerged as innovative reliable tools to investigate how tumors regulate their TME to counteract antitumor immunity and the mechanism of tumor resistance to immunotherapy. In this comprehensive review, we focus on recent advances in tumor organoid-on-a-chip platforms for studying the interaction between the TME and the immune system. We first review different factors of the TME that recent microfluidic in vitro systems reproduce to generate advanced tools to imitate the crosstalk between the TME and the immune system. Then, we discuss their applications in the assessment of different immunotherapies' efficacy using tumor organoid-on-a-chip platforms. Finally, we present an overview and the outlook of engineered microfluidic platforms in investigating the interactions between cancer and immune systems, and the adoption of patient-on-a-chip models in clinical applications toward personalized immunotherapy.

Recent progress of inertial microfluidic-based cell separation

Cell separation has consistently been a pivotal technology of sample preparation in biomedical research. Compared with conventional bulky cell separation technologies applied in the clinic, cell separation based on microfluidics can accurately manipulate the displacement of liquid or cells at the microscale, which has great potential in point-of-care testing (POCT) applications due to small device size, low cost, low sample consumption, and high operating accuracy. Among various microfluidic cell separation technologies, inertial microfluidics has attracted great attention due to its simple structure and high throughput. In recent years, many researchers have explored the principles and applications of inertial microfluidics and developed different channel structures, including straight channels, curved channels, and multistage channels. However, the recently developed multistage channels have not been discussed and classified in detail compared with more widely discussed straight and curved channels. Therefore, in this review, a comprehensive and detailed review of recent progress in the multistage channel is presented. According to the channel structure, the inertial microfluidic separation technology is divided into (i) straight channel, (ii) curved channel, (iii) composite channel, and (iv) integrated device. The structural development of straight and curved channels is discussed in detail. And based on straight and curved channels, the multistage cell separation structures are reviewed, with a special focus on a variety of latest structures and related innovations of composite and integrated channels. Finally, the future prospects for the existing challenges in the development of inertial microfluidic cell separation technology are presented.

Molecular Detection of Infectious Laryngotracheitis Virus in Chickens with a Microfluidic Chip

Simple Summary

Infectious laryngotracheitis (ILT) presents a major risk to the chicken industry. Rapid, specific, simple, and point-of-need molecular detection of the virus is crucial to enable chicken farms to take timely action and contain the spread of infection. The current study describes an isothermal amplification assay for infectious laryngotracheitis virus (ILTV) infection and the implementation of this assay in a microfluidic chip suitable for molecular detection and quasi-quantification of ILTV in diagnostic veterinary laboratories with low resources and poultry farms. Our assay performance was compared and favorably agreed with quantitative PCR (qPCR). Clinical tests of our assay and chip with samples from diseased chickens demonstrated good concordance with the gold-standard benchtop qPCR assay.

Abstract

Infectious laryngotracheitis (ILT) is a viral disease of chickens’ respiratory system that imposes considerable financial burdens on the chicken industry. Rapid, simple, and specific detection of this virus is crucial to enable proper control measures. Polymerase chain reaction (PCR)-based molecular tests require relatively expensive instruments and skilled personnel, confining their application to centralized laboratories. To enable chicken farms to take timely action and contain the spread of infection, we describe a rapid, simple, semi-quantitative benchtop isothermal amplification (LAMP) assay, and a field-deployable microfluidic device for the diagnosis of ILTV infection in chickens. Our assay performance was compared and favorably agreed with quantitative PCR (qPCR). The sensitivity of our real-time LAMP test is 250 genomic copies/reaction. Clinical performance of our microfluidic device using samples from diseased chickens showed 100% specificity and 100% sensitivity in comparison with benchtop LAMP assay and the gold-standard qPCR. Our method facilitates simple, specific, and rapid molecular ILTV detection in low-resource veterinary diagnostic laboratories and can be used for field molecular diagnosis of suspected ILT cases.

Laser-Engineered Superhydrophobic Polydimethylsiloxane for Highly Efficient Water Manipulation

Low-cost, high-quality, and large-area superhydrophobic surfaces are in high demand. This study demonstrates laser-engineered polydimethylsiloxane (PDMS) as a platform for versatile and highly efficient water manipulation. The fabrication process consists of two steps: patterning PDMS with arrayed microlenses and laser pulse scanning. The obtained PDMS is superhydrophobic and exhibits excellent chemical resistance, UV stability, pressure robustness, and substantial mechanical durability. Notably, there is no significant change in the water contact angles after storage in air for 14 months. Microstructural analysis revealed that the sample contained stable nanostructured inorganics such as crystalline silicon, silicon carbide, and sp³-like carbon. The superhydrophobic surface was demonstrated to have versatile and wide applications in oil/water separation and water collection.

Recent innovations in cost-effective polymer and paper hybrid microfluidic devices

Hybrid microfluidic systems that are composed of multiple different types of substrates have been recognized as a versatile and superior platform, which can draw benefits from different substrates while avoiding their limitations. This review article introduces the recent innovations of different types of low-cost hybrid microfluidic devices, particularly focusing on cost-effective polymer- and paper-based hybrid microfluidic devices. In this article, the fabrication of these hybrid microfluidic devices is briefly described and summarized. We then highlight various hybrid microfluidic systems, including polydimethylsiloxane (PDMS)-based, thermoplastic-based, paper/polymer hybrid systems, as well as other emerging hybrid systems (such as thread-based). The special benefits of using these hybrid systems have been summarized accordingly. A broad range of biological and biomedical applications using these hybrid microfluidic devices are discussed in detail, including nucleic acid analysis, protein analysis, cellular analysis, 3D cell culture, organ-on-a-chip, and tissue engineering. The perspective trends of hybrid microfluidic systems involving the improvement of fabrication techniques and broader applications are also discussed at the end of the review.

The impact of pertussis in infants: insights from a hospital-based enhanced surveillance system, Lazio region, Italy, 2016 to 2019

Background

Routine surveillance systems for pertussis often suffer from under-recognition and under-reporting.

Aim

Our aim was to describe the epidemiology and the clinical features of pertussis in children younger than 1 year in an Italian region, detected through an enhanced hospital surveillance system.

Methods

From 2016 to 2019, we monitored the incidence and the clinical characteristics of hospitalised pertussis cases younger than 1 year in two paediatric hospitals involved in the PERTINENT project.

Results

We detected 141 pertussis cases, corresponding to an estimated incidence of 105.8 per 100.000 in 2016, 91.7 per 100.000 in 2017, 64.5 per 100.000 in 2018 and 40.9 per 100.000 in 2019, based on the hospitals’ catchment area, roughly corresponding to the Lazio region. A total of 101 cases (77.1%) had a household member with cough or other respiratory symptoms. The most frequent combination of symptoms was paroxysmal cough with apnoea in the absence of fever. Almost 40% had been prescribed an antibiotic treatment before hospitalisation, and the median time from symptom onset to contact with the hospital was 8 days. Thirty-one (22.0%) had complications.

Conclusion

An enhanced surveillance system showed a high incidence of pertussis among infants in the Lazio region, where the impact of this disease may still be underestimated. Increasing the coverage of pertussis immunisation among pregnant women and improving the capacity for early detection in primary care may contribute to reducing the impact of pertussis among infants.

Multicolorimetric ELISA biosensors on a paper/polymer hybrid analytical device for visual point-of-care detection of infection diseases

Enzyme-linked immunosorbent assay (ELISA) is widely used for the detection of disease biomarkers. However, it utilizes time-consuming procedures and expensive instruments, making it infeasible for point-of-care (POC) analysis especially in resource-limited settings. In this work, a multicolorimetric ELISA biosensor integrated on a paper/polymer hybrid microfluidic device was developed for rapid visual detection of disease biomarkers at point of care, without using costly equipment. This multicolormetric ELISA platform was built on multiple distinct color variants resulted from the catalytic oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) and the etching of gold nanorods (AuNRs). The vivid color changes could be easily distinguished by the naked eye, and their red mean values allowed quantitative biomarker detection, without using any sophisticated instruments. When this multicolorimetric ELISA was integrated on a paper/polymer hybrid analytical device, it not only provided integrated processing and high portability but also enabled fast assays in about 50 min due to the unique advantages of paper/polymer hybrid devices. The limit of detection of 9.1 ng/μL of the hepatitis C virus core antigen, a biomarker for hepatitis C, was achieved using this multicolorimetric ELISA platform. This multicolor ELISA analytical device provides a new versatile, user-friendly, affordable, and portable immunosensing platform with high potential for on-site detections of various viruses, proteins, and biomarkers for low-resource settings such as at home, public venues, rural areas, and developing nations.

A highly efficient preconcentration route for rapid and sensitive detection of endotoxin based on an electrochemical biosensor

An impedimetric aptasensor for the detection of endotoxin in a microfluidic chip was proposed, in which the Apt/AuNPs/SPCE sensing surface was fabricated in a screen-printed electrode with good biological activity and stability. The quantitative detection of endotoxin was accomplished by electrochemical impedance spectroscopy (EIS) measurement before and after exposing to samples. The impedance biosensor offers an ultrasensitive and selective detection of endotoxin down to 500 pg mL-1 with a wide linear range from 500 pg mL-1 to 200 ng mL-1. According to the Langmuir isotherm model, the interactions between the target molecules and the sensing surface had been analyzed and strong binding was concluded. Compared to the traditional static incubation methods, the microfluidic biosensor realizes the enrichment of endotoxin owing to the confined space and continuous flow nature, so that the lowest detection concentration is reduced from 5 ng mL-1 to 500 pg mL-1, which is much lower than the existing technology, and the total assay time is shortened from 1.0 h to 0.5 h. The proposed microfluidic impedance biosensor provides a new strategy for the design of an aptasensor to realize the rapid detection of target biomolecules with high sensitivity and it can be integrated into wearable medical devices due to its flexible properties.

Aptamer-functionalized metal-organic frameworks (MOFs) for biosensing

As a class of crystalline porous materials, metal-organic frameworks (MOFs) have attracted increasing attention. Due to the nanoscale framework structure, adjustable pore size, large specific surface area, and good chemical stability, MOFs have been applied widely in many fields such as biosensors, biomedicine, electrocatalysis, energy storage and conversions. Especially when they are combined with aptamer functionalization, MOFs can be utilized to construct high-performance biosensors for numerous applications ranging from medical diagnostics and food safety inspection, to environmental surveillance. Herein, this article reviews recent innovations of aptamer-functionalized MOFs-based biosensors and their bio-applications. We first briefly introduce different functionalization methods of MOFs with aptamers, which provide a foundation for the construction of MOFs-based aptasensors. Then, we comprehensively summarize different types of MOFs-based aptasensors and their applications, in which MOFs serve as either signal probes or signal probe carriers for optical, electrochemical, and photoelectrochemical detection, with an emphasis on the former. Given recent substantial research interests in stimuli-responsive materials and the microfluidic lab-on-a-chip technology, we also present the stimuli-responsive aptamer-functionalized MOFs for sensing, followed by a brief overview on the integration of MOFs on microfluidic devices. Current limitations and prospective trends of MOFs-based biosensors are discussed at the end.

A visual bio-barcode immunoassay for sensitive detection of triazophos based on biochip silver staining signal amplification

Herein, a novel visual method for detecting triazophos based on competitive bio-barcode immunoassay was described. The competitive immunoassay was established by gold nanoparticles (AuNPs), magnetic microparticle (MMPs) and triazophos, combined with biochip hybridization system to detect the residual of triazophos in water and apple. Because AuNPs carried many bio-barcodes, which hybridized with labeled DNA on the biochip, catalyzed signal amplification using silver staining was detected by grayscale values as well as the naked eye. Notably, the grayscale values decreases with increasing the concentrations of triazophos, and the color change weakened gradually. The detection range was in between 0.05 and 10 ng/mL and the minimum detection limit was set at 0.04 ng/mL. Percent recovery calculated from spiked water and apple samples ranged between 55.4 and 107.8% with relative standard deviations (RSDs) of 12.4-24.9%. It has therefore been shown that this protocol provides a new insight for rapid detection of small molecule pesticides in various matrices.

Advances in point-of-care nucleic acid extraction technologies for rapid diagnosis of human and plant diseases

Global health and food security constantly face the challenge of emerging human and plant diseases caused by bacteria, viruses, fungi, and other pathogens. Disease outbreaks such as SARS, MERS, Swine Flu, Ebola, and COVID-19 (on-going) have caused suffering, death, and economic losses worldwide. To prevent the spread of disease and protect human populations, rapid point-of-care (POC) molecular diagnosis of human and plant diseases play an increasingly crucial role. Nucleic acid-based molecular diagnosis reveals valuable information at the genomic level about the identity of the disease-causing pathogens and their pathogenesis, which help researchers, healthcare professionals, and patients to detect the presence of pathogens, track the spread of disease, and guide treatment more efficiently. A typical nucleic acid-based diagnostic test consists of three major steps: nucleic acid extraction, amplification, and amplicon detection. Among these steps, nucleic acid extraction is the first step of sample preparation, which remains one of the main challenges when converting laboratory molecular assays into POC tests. Sample preparation from human and plant specimens is a time-consuming and multi-step process, which requires well-equipped laboratories and skilled lab personnel. To perform rapid molecular diagnosis in resource-limited settings, simpler and instrument-free nucleic acid extraction techniques are required to improve the speed of field detection with minimal human intervention. This review summarizes the recent advances in POC nucleic acid extraction technologies. In particular, this review focuses on novel devices or methods that have demonstrated applicability and robustness for the isolation of high-quality nucleic acid from complex raw samples, such as human blood, saliva, sputum, nasal swabs, urine, and plant tissues. The integration of these rapid nucleic acid preparation methods with miniaturized assay and sensor technologies would pave the road for the "sample-in-result-out" diagnosis of human and plant diseases, especially in remote or resource-limited settings.

Advances in Portable Visual Detection of Pathogenic Bacteria

Food safety and regulation of consumer welfare are of great concern, so it is necessary to be able to detect pathogenic bacteria quickly and effectively. Although traditional methods of pathogen detection are reliable and widely used, the detection and analysis processes are cumbersome and time-consuming, which is not conducive to fast assays in the field. New detection strategies have emerged in recent years, especially point-of-care testing (POCT) methods, which do not rely on the laboratory and have become an important development direction for pathogen detection. Many visual detection schemes have been developed that integrate portable glucose meters (PGMs), test strips, smartphones, and other portable devices. Importantly, portable and ultrasensitive biosensors have vast promise in detecting pathogens, as they can be suitable tools for clinical diagnosis and the regulation of food safety. This Review focuses on the latest advances in portable device-based methods for visual detection of pathogens, evaluating their advantages and disadvantages.

Low-Cost Quantitative Photothermal Genetic Detection of Pathogens on a Paper Hybrid Device Using a Thermometer

Tuberculosis (TB), one of the deadliest infectious diseases, is caused by Mycobacterium tuberculosis (MTB) and remains a public health problem nowadays. Conventional MTB DNA detection methods require sophisticated infrastructure and well-trained personnel, which leads to increasing complexity and high cost for diagnostics and limits their wide accessibility in low-resource settings. To address these issues, we have developed a low-cost photothermal biosensing method for the quantitative genetic detection of pathogens such as MTB DNA on a paper hybrid device using a thermometer. First, DNA capture probes were simply immobilized on paper through a one-step surface modification process. After DNA sandwich hybridization, oligonucleotide-functionalized gold nanoparticles (AuNPs) were introduced on paper and then catalyzed the oxidation reaction of 3,3',5,5'-tetramethylbenzidine (TMB). The produced oxidized TMB, acting as a strong photothermal agent, was used for the photothermal biosensing of MTB DNA under 808 nm laser irradiation. Under optimal conditions, the on-chip quantitative detection of the target DNA was readily achieved using an inexpensive thermometer as a signal recorder. This method does not require any expensive analytical instrumentation but can achieve higher sensitivity and there are no color interference issues, compared to conventional colorimetric methods. The method was further validated by detecting genomic DNA with high specificity. To the best of our knowledge, this is the first photothermal biosensing strategy for quantitative nucleic acid analysis on microfluidics using a thermometer, which brings fresh inspirations on the development of simple, low-cost, and miniaturized photothermal diagnostic platforms for quantitative detection of a variety of diseases at the point of care.

A profile of the Simplexa™ Bordetella Direct assay for the detection and differentiation of Bordetella pertussis and Bordetella parapertussis in nasopharyngeal swabs

INTRODUCTION

Pertussis is a highly contagious respiratory infection caused by Bordetella pertussis and to minor extent B. parapertussis. Despite high vaccination coverage, epidemics persist worldwide. Laboratory testing with the capacity to support increasing demand and generate fast and accurate results is needed to promptly provide treatment to mitigate symptoms, prevent transmission, and thus impact infection control and disease surveillance.

AREAS COVERED

This review will describe the features of the Simplexa™ Bordetella Direct Assay and compare this technology with other existing assays. Unmet needs and future directions will be discussed.

EXPERT COMMENTARY

Resurgence of pertussis highlights the importance of reliable and accurate diagnosis. The Simplexa™ Bordetella Direct Assay provides an easy workflow, reduced hand-on time, less risk of contamination, and rapid turnaround time. The use of efficient molecular assays in routine clinical laboratory is valuable for increasing demand, improvement of infection control, and surveillance.

Fighting COVID-19: Integrated Micro- and Nanosystems for Viral Infection Diagnostics

The pandemic of coronavirus disease 2019 (COVID-19) highlights the importance of rapid and sensitive diagnostics of viral infection that enables the efficient tracing of cases and the implementation of public health measures for disease containment. The immediate actions from both academia and industry have led to the development of many COVID-19 diagnostic systems that have secured fast-track regulatory approvals and have been serving our healthcare frontlines since the early stage of the pandemic. On diagnostic technologies, many of these clinically validated systems have significantly benefited from the recent advances in micro- and nanotechnologies in terms of platform design, analytical method, and system integration and miniaturization. The continued development of new diagnostic platforms integrating micro- and nanocomponents will address some of the shortcomings we have witnessed in the existing COVID-19 diagnostic systems. This Perspective reviews the previous and ongoing research efforts on developing integrated micro- and nanosystems for nucleic acid-based virus detection, and highlights promising technologies that could provide better solutions for the diagnosis of COVID-19 and other viral infectious diseases. With the summary and outlook of this rapidly evolving research field, we hope to inspire more research and development activities to better prepare our society for future public health crises.

A new method to amplify colorimetric signals of paper-based nanobiosensors for simple and sensitive pancreatic cancer biomarker detection

A low-cost, sensitive, and disposable paper-based immunosensor for instrument-free colorimetric detection of pancreatic cancer biomarker PEAK1 was reported for the first time by capitalizing the catalytic properties of gold nanoparticles in colour dye degradation. This simple signal amplification method enhances the detection sensitivity by about 10 fold.

A fully automated centrifugal microfluidic system for sample-to-answer viral nucleic acid testing

The outbreak of virus-induced infectious diseases poses a global public-health challenge. Nucleic acid amplification testing (NAAT) enables early detection of pandemic viruses and plays a vital role in preventing onward transmission. However, the requirement of skilled operators, expensive instrumentation, and biosafety laboratories has hindered the use of NAAT for screening and diagnosis of suspected patients. Here we report development of a fully automated centrifugal microfluidic system with sample-in-answer-out capability for sensitive, specific, and rapid viral nucleic acid testing. The release of nucleic acids and the subsequent reverse transcription loop-mediated isothermal amplification (RT-LAMP) were integrated into the reaction units of a microfluidic disc. The whole processing steps such as injection of reagents, fluid actuation by rotation, heating and temperature control, and detection of fluorescence signals were carried out automatically by a customized instrument. We validate the centrifugal microfluidic system using oropharyngeal swab samples spiked with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) armored RNA particles. The estimated limit of detection for armored RNA particles is 2 copies per reaction, the throughput is 21 reactions per disc, and the assay sample-to-answer time is approximately 70 min. This enclosed and automated microfluidic system efficiently avoids viral contamination of aerosol, and can be readily adapted for virus detection outside the diagnostic laboratory.

A fully automated centrifugal microfluidic system for sample-to-answer viral nucleic acid testing

The outbreak of virus-induced infectious diseases poses a global public-health challenge. Nucleic acid amplification testing (NAAT) enables early detection of pandemic viruses and plays a vital role in preventing onward transmission. However, the requirement of skilled operators, expensive instrumentation, and biosafety laboratories has hindered the use of NAAT for screening and diagnosis of suspected patients. Here we report development of a fully automated centrifugal microfluidic system with sample-in-answer-out capability for sensitive, specific, and rapid viral nucleic acid testing. The release of nucleic acids and the subsequent reverse transcription loop-mediated isothermal amplification (RT-LAMP) were integrated into the reaction units of a microfluidic disc. The whole processing steps such as injection of reagents, fluid actuation by rotation, heating and temperature control, and detection of fluorescence signals were carried out automatically by a customized instrument. We validate the centrifugal microfluidic system using oropharyngeal swab samples spiked with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) armored RNA particles. The estimated limit of detection for armored RNA particles is 2 copies per reaction, the throughput is 21 reactions per disc, and the assay sample-to-answer time is approximately 70 min. This enclosed and automated microfluidic system efficiently avoids viral contamination of aerosol, and can be readily adapted for virus detection outside the diagnostic laboratory.

Electronic Supplementary Material

Supplementary material is available for this article at 10.1007/s11426-020-9800-6 and is accessible for authorized users.

Rapid Pomegranate Juice Authentication Using a Simple Sample-to-Answer Hybrid Paper/Polymer-Based Lab-on-a-Chip Device

As a super fruit, pomegranate and its juice have attracted increased consumer demands during the past decades. Given the high production cost and market price, adulteration of pomegranate juice is highly likely to occur. To authenticate pomegranate juice and avoid the addition of cheaper fruit juices, such as apple and grape, an analytical method based on loop-mediated isothermal amplification (LAMP) was developed. This LAMP-based authentication method achieved highly sensitive (i.e., 10 pg for pomegranate DNA and 100 pg for grape and apple DNA) and specific detection of pomegranate, apple, and grape DNA present in fresh fruit juice. To further simplify the overall analysis, a hybrid paper/polymer-based lab-on-a-chip (LOC) platform was designed to integrate DNA extraction, LAMP reaction, and LAMP result visualization onto a single device. This LOC device was able to detect 2 μL of fresh pomegranate juice and 5 μL of fresh apple and grape juice. Using a homemade portable heating device, the overall analysis could be completed in ∼1 h in an almost instrument-free setting. The cost for each authentication test is estimated to be ∼4 USD and the reusable homemade portable heating device is ∼15 USD. This LAMP-based simple sample-to-answer hybrid paper/polymer-based LOC device has high potential to be adopted by government laboratories and the food industry to rapidly and routinely authenticate pomegranate juice even in a resource-limited environment.

Remotely tunable microfluidic platform driven by nanomaterial-mediated on-demand photothermal pumping

The requirement of on-demand microfluidic pumps and instrument-free readout methods remains a major challenge for the development of microfluidics. Herein, a new type of microfluidic platform, an on-demand photothermal microfluidic pumping platform, has been developed using an on-chip nanomaterial-mediated photothermal effect as novel and remotely tunable microfluidic driving force. The photothermal microfluidic pumping performance can be adjusted remotely by tuning the irradiation parameters, without changing on-chip parameters or replacing enzymes or other reagents. In contrast to graphene oxide, Prussian blue nanoparticles with higher photothermal conversion efficiency were used as the model photothermal agent to demonstrate the proof of concept. The on-chip pumping distance is linearly correlated with both the irradiation time and the nanomaterial concentration. The applications of photothermal microfluidic pumping have been demonstrated in multiplexed on-chip transport of substances, such as gold nanoparticles, and visual quantitative bar-chart detection of cancer biomarkers without using specialized instruments. Upon contact-free irradiation using a laser pointer, a strong on-chip nanomaterial-mediated photothermal effect can serve as a robust and remotely tunable microfluidic pump in a PMMA/PDMS hybrid bar-chart chip to drive ink bars in a visual quantitative readout fashion. This is the first report on a photothermal microfluidic pumping platform, which has great potential for various microfluidic applications.

End-point dual specific detection of nucleic acids using CRISPR/Cas12a based portable biosensor

A CRISPR/Cas12a based portable biosensor (Cas12a-PB) was developed to simultaneously visually detect CaMV35S promoter and Lectin gene from genetically modified (GM) soybean powders (Roundup Ready@). The Cas12a-PB, mainly made of polymethylmethacrylate (PMMA) and PMMA tape, has a connection structure, three channels and three detection chambers. The CRISPR/Cas12a detection reagents were preloaded in detection chambers and the reaction tube was connected to the connection structure by screw threads. After amplification, the amplicons were gone into three detection chambers by swinging the Cas12a-PB to conduct dual detection. Positive samples would produce green fluorescence while negative samples were black under the irradiation of 490 nm LED light. In this study, the Cas12a-PB successively combined with ordinary PCR, rapid PCR and loop-mediated isothermal amplification (LAMP) to achieve dual detection, which made detection process more convenient and portable. As low as 0.1% transgenic ingredients in soybean powders could be detected and the specificity of Cas12a-PB was confirmed with GM maize powders (MON810, GA21), GM soybean powders (DP305423), non-GM peanut and rice as targets. In the end, an amplification chamber combining with Cas12a-PB on a PMMA chip was further designed to eliminate the use of reaction tube and mineral oil, which made operation simpler. The established Cas12a-PB would provide a new reliable solution for multiple targets detection in clinic diagnostics, food safety, etc.

One-Step Surface Modification to Graft DNA Codes on Paper: The Method, Mechanism, and Its Application

Glass slides have been widely used for DNA immobilization in DNA microarray and numerous bioassays for decades, whereas they are faced with limitations of low probe density, time-consuming modification steps, and expensive instruments. In this work, a simple one-step surface modification method using 3-aminopropyl trimethoxysilane (APTMS) has been developed and applied to graft DNA codes on paper. Higher DNA immobilization efficiency was obtained in comparison with that in a conventional method using glass slides. Fluorescence detection, X-ray photoelectron spectroscopy (XPS), infrared spectra (FT-IR), and pH influence studies were employed to characterize the surface modification and subsequent DNA immobilization, which further reveals a mechanism in which this method lies in ionic interactions between the positively charged APTMS-modified paper surface and negatively charged DNA probes. Furthermore, an APTMS-modified paper-based device has been developed to demonstrate application in low-cost detection of a foodborne pathogen, Giardia lamblia, with high sensitivity (the detection limit of 22 nM) and high specificity. Compared with conventional methods using redundant cross-linking reactions, our method is simpler, faster, versatile, and lower-cost, enabling broad applications of paper-based bioassays especially for point-of-care detection in resource-poor settings.

Frugal Innovation for Point-of-Care Diagnostics Controlling Outbreaks and Epidemics

Today epidemics of infectious diseases occur more often and spread both faster and further due to globalization and changes in our lifestyle. One way to meet these biological threats are so-called "Frugal Innovations", which focus on the development of affordable, rapid, and easy-to-use diagnostics with widespread use. In this context, point-of-care-tests (POCTs), performed at the patient's bedside, reduce extensive waiting times and unnecessary treatments and enable effective containment measures. This Perspective covers advances in POCT diagnostics on the basis of frugal innovation characteristics that will enable a faster, less expensive, and more convenient reaction to upcoming epidemics. Established POCT systems on the health care market, as well as currently evolving technological advancements in that sector are discussed. Progress in POCT technology and insights on how to most effectively use them allows the handling of more patients in a shorter time frame and consequently improves clinical outcomes at lower cost.

A Low-Cost Nanomaterial-based Electrochemical Immunosensor on Paper for High-Sensitivity Early Detection of Pancreatic Cancer

Due to the lack of specific early detection methods for pancreatic cancer, it usually goes undetected until it is advanced. By employing paper-based electrodes (PPE), herein we for the first time developed a disposable low-cost paper-based immunosensor for rapid early quantitative detection of pancreatic cancer with a new biomarker, pseudopodium-enriched atypical kinase one, SGK269 (PEAK1). The immunosensor was constructed by fabricating PPEs immobilized with the versatile nanomaterial graphene oxide for the incorporation of antibodies to form an immunosensing platform, without the need of complicated surface modification. After it was confirmed that the PPEs exhibited excellent electrochemical properties, a sandwich-type electrochemical immunosensor was subsequently constructed by employing graphene oxide layers immobilized with anti-PEAK1, and the antibody conjugated with gold nanoparticles (AuNPs-tagged-Anti PEAK1). Further, spectral and surface characteristic studies confirmed the formation of the immunosensing platform. The immunosensor for PEAK1 exhibited a wide linear range between 10 pg mL^-1 and 10⁶ pg mL^-1 with a low limit of detection (LOD) of 10 pg mL^-1. The obtained results point towards rapid, sensitive, and specific early diagnosis of pancreatic cancer at the point of care and other low-resource settings.

Superhydrophobic Polydimethylsiloxane via Nanocontact Molding of Solvent Crystallized Polycarbonate: Optimized Fabrication, Mechanistic Investigation, and Application Potential

Herein, we describe a benchtop protocol to create superhydrophobic polydimethylsiloxane (PDMS) via nanocontact molding of polycarbonate (PC) that was crystallized by controlled solvent treatment. The crystallized PC chains rearrange into a network of spherulites (spherical semicrystalline domains); the overall surface is rough on the micrometer-scale, while the spherulites themselves consist of nanoscale features. It was confirmed via conventional spectroscopic and high-resolution microscopic investigation that such hierarchical roughness is key to the development of superhydrophobic PC and the substantial enhancement upon PDMS molding. Thus, the prepared PDMS surface has excellent superhydrophobicity with an optimized contact angle of 172 ± 1° and a sliding angle of <1°, superior to those prepared from more elaborate techniques, such as plasma sputtering and laser etching. More importantly, the knowledge acquired regarding the structural transition and superhydrophobicity development would be beneficial to engineering and evaluating templates for many other polymeric nanostructures and functional surfaces.

Ultrafast Photonic PCR Based on Photothermal Nanomaterials

Over the past few decades, PCR has been the gold standard for detecting nucleic acids (NAs) in various biomedical fields. However, there are several limitations associated with conventional PCR, such as complicated operation, need for bulky equipment, and, in particular, long thermocycling time. Emerging nanomaterials with photothermal effects have shown great potential for developing a new generation of PCR: ultrafast photonic PCR. Here, we review recent applications of photothermal nanomaterials in ultrafast photonic PCR. First, we introduce emerging photothermal nanomaterials and their light-to-heat energy conversion process in photonic PCR. We then review different photothermal nanomaterial-based photonic PCRs and compare their merits and drawbacks. Finally, we summarize existing challenges with photonic PCR and hypothesize its promising future research directions.

A reusable PMMA/paper hybrid plug-and-play microfluidic device for an ultrasensitive immunoassay with a wide dynamic range

Conventional colorimetric enzyme-linked immunosorbent assay (ELISA) is a time-consuming laboratory assay that is not very sensitive and consumes a large amount of samples. Herein, the development of a reusable, cost-effective, and eco-friendly poly(methyl methacrylate) (PMMA)/paper hybrid plug-and-play (PnP) device for high-sensitivity immunoassay by analyte enrichment and efficient passing-through washing has been reported. The PMMA device has multiple slots where a pre-patterned paper substrate can be inserted. The sample flows back-and-forth through a low-cost, 3D paper substrate within the PMMA channels, thereby enhancing the amount of analyte adsorbed and dramatically increasing the sensitivity while decreasing the assay time. After the enrichment assay, the paper substrate can simply be pulled out of the device, and the results can be qualitatively viewed with the naked eye or scanned through a simple desktop scanner for quantitative analysis. The paper substrate can be replaced with a new substrate so that the device can be reused. The limits of detection (LODs) of 200 pg/mL for immunoglobulin G (IgG) and 270 pg/mL for hepatitis B surface antigen (HBsAg) were obtained. This IgG assay is at least 10 times more sensitive than commercial ELISA kits. In addition, the PnP ELISA exhibited a significant increase in the linear dynamic range from 3 orders of magnitude in a common paper-based device to a wide range of six orders of magnitude in the PnP hybrid device. This reusable PnP device has great potential for the low-cost yet high-sensitivity detection of infectious diseases, cancers, and other important biomolecules.

Immunomodulation as a Novel Strategy for Prevention and Treatment of Bordetella spp. Infections

Well-adapted pathogens have evolved to survive the many challenges of a robust immune response. Defending against all host antimicrobials simultaneously would be exceedingly difficult, if not impossible, so many co-evolved organisms utilize immunomodulatory tools to subvert, distract, and/or evade the host immune response. Bordetella spp. present many examples of the diversity of immunomodulators and an exceptional experimental system in which to study them. Recent advances in this experimental system suggest strategies for interventions that tweak immunity to disrupt bacterial immunomodulation, engaging more effective host immunity to better prevent and treat infections. Here we review advances in the understanding of respiratory pathogens, with special focus on Bordetella spp., and prospects for the use of immune-stimulatory interventions in the prevention and treatment of infection.

Spatiotemporally Controlled Multiplexed Photothermal Microfluidic Pumping under Monitoring of On-Chip Thermal Imaging

Intelligent contactless microfluidic pumping strategies have been increasingly desirable for operation of lab-on-a-chip devices. Herein, we present a photothermal microfluidic pumping strategy for on-chip multiplexed cargo transport in a contactless and spatiotemporally controllable fashion based on the application of near-infrared laser-driven photothermal effect in microfluidic paper-based devices (μPDs). Graphene oxide (GO)-doped thermoresponsive poly(N-isopropylacrylamide)-acrylamide hydrogels served as the photothermally responsive cargo reservoirs on the μPDs. In response to remote contactless irradiation by an 808 nm laser, on-chip phase transition of the composite hydrogels was actuated in a switchlike manner as a result of the photothermal effect of GO, enabling robust on-chip pumping of cargoes from the hydrogels to predefined arrays of reaction zones. The thermal imaging technique was employed to monitor the on-chip photothermal pumping process. The microfluidic pumping performance can be spatiotemporally controlled in a quantitative way by remotely tuning the laser power, irradiation time, and GO concentration. The pumping strategy was exemplified by FeCl₃ and horseradish peroxidase as the model cargoes to implement on-chip Prussian blue- and 3,3',5,5'-tetramethylbenzidine-based colorimetric reactions, respectively. Furthermore, multiplexed on-demand microfluidic pumping was achieved by flexibly adjusting the irradiation pathway and the microfluidic pattern. The new microfluidic pumping strategy shows great promise for diverse microfluidic applications due to its flexibility, high integratability into lab-on-a-chip devices, and contactless and spatiotemporal controllability.

Recent advances in microfluidic platforms for single-cell analysis in cancer biology, diagnosis and therapy

Understanding molecular, cellular, genetic and functional heterogeneity of tumors at the single-cell level has become a major challenge for cancer research. The microfluidic technique has emerged as an important tool that offers advantages in analyzing single-cells with the capability to integrate time-consuming and labour-intensive experimental procedures such as single-cell capture into a single microdevice at ease and in a high-throughput fashion. Single-cell manipulation and analysis can be implemented within a multi-functional microfluidic device for various applications in cancer research. Here, we present recent advances of microfluidic devices for single-cell analysis pertaining to cancer biology, diagnostics, and therapeutics. We first concisely introduce various microfluidic platforms used for single-cell analysis, followed with different microfluidic techniques for single-cell manipulation. Then, we highlight their various applications in cancer research, with an emphasis on cancer biology, diagnosis, and therapy. Current limitations and prospective trends of microfluidic single-cell analysis are discussed at the end.