Multiplexed Instrument-Free Bar-Chart SpinChip Integrated with Nanoparticle-Mediated Magnetic Aptasensors for Visual Quantitative Detection of Multiple Pathogens

Designing and prototyping a novel biosensor based on a volumetric bar-chart chip for urea detection

A volumetric bar-chart chip (V-chip) is a microfluidic device based on distance-based quantitative measurement that visualizes analyte concentration without the need for apparatus or data processing. This typically utilizes special receptors and catalysis parts that generate oxygen, so ink can be moved inside the channels, and enables instant visual quantitation of the analyte. However, the low stability of some macromolecules, the use of expensive catalysts, and difficulty in controlling the process cause inaccurate readings, and therefore, limit further development and the use of these systems. In this article, we introduced a novel approach that eliminates the use of catalysts in V-chips and provides an efficient and simple path in the design of biosensors. The product of the enzymatic reaction of urease with urea is bicarbonate, which turns into CO2 gas in an acidic environment. Therefore, the amount of gas produced is proportional to the amount of urea in the sample, and it can be quantitatively measured by visual detection from the amount of ink movement caused by CO2 gas pressure. This biosensor has a linear response range of 0 to 1000 μg ml-1 and a detection limit of 3.6 μg ml-1 in raw milk. The recovery of urea in raw milk at 100 and 400 μg ml-1 concentrations was 96.5% and 98.9%, respectively. This volumetric chip shows potential for determining urea levels in real samples without requiring additional equipment. The combination of the sensitivity and specificity of enzymatic reactions, inherent gas-generating reactions, and the processability of microchips discussed in this paper can be the basis for the comprehensive development of volumetric chips, which can create a new path for the development of efficient and cheap biosensors.

Light-Driven Photocatalytic-Photothermal Synergetic System for Portable and Sensitive Nucleic Acid Quantification

Photosensitizers and photothermal agents have attracted increasing attention for in vitro diagnosis, but the combination remains challenging. Herein, a light-driven photocatalytic-photothermal synergetic system integrated microfluidic distance-based analytical device (PCPT-μDAD) for visual, portable, sensitive, and quantitative detection of targets was developed. Target DNA was recognized and initiated the hybridization chain reaction to form a double-stranded DNA/SYBR Green I (dsDNA/SG-I) complex. By applying the photosensitization of the dsDNA/SG-I complex and the photothermal effect of oxidized 3,3',5,5'-tetramethylbenzidine, the target concentration can effectively translate into a visual distance signal readout. Importantly, the light-driven PCPT-μDAD greatly improves the controllability of catalytic reactions and signal amplification efficiency. The light-driven PCPT-μDAD shows a low limit of detection (fM level), good stability, and high reproducibility for nucleic acid detection.

Aptasensors: employing molecular probes for precise medical diagnostics and drug monitoring

Accurate detection and monitoring of therapeutic drug levels are vital for effective patient care and treatment management. Aptamers, composed of single-stranded DNA or RNA molecules, are integral components of biosensors designed for both qualitative and quantitative detection of biological samples. Aptasensors play crucial roles in target identification, validation, detection of drug-target interactions and screening potential of drug candidates. This review focuses on the pivotal role of aptasensors in early disease detection, particularly in identifying biomarkers associated with various diseases such as cancer, infectious diseases and cardiovascular disorders. Aptasensors have demonstrated exceptional potential in enhancing disease diagnostics and monitoring therapeutic drug levels. Aptamer-based biosensors represent a transformative technology in the field of healthcare, enabling precise diagnostics, drug monitoring and disease detection.

Room temperature roll-to-roll additive manufacturing of polydimethylsiloxane-based centrifugal microfluidic device for on-site isolation of ribonucleic acid from whole blood

Polymer-based lab-on-a-disc (LoaD) devices for isolating ribonucleic acid (RNA) from whole blood samples have gained considerable attention for accurate biomedical analysis and point-of-care diagnostics. However, the mass production of these devices remains challenging in manufacturing cost and sustainability, primarily due to the utilization of a laser cutter or router computer numerical control (CNC) machine for engraving and cutting plastics in the conventional prototyping process. Herein, we reported the first energy-efficient room-temperature printing-imprinting integrated roll-to-roll manufacturing platform for mass production of a polydimethylsiloxane (PDMS)-based LoaD to on-site isolate ribonucleic acid (RNA) from undiluted blood samples. We significantly reduced energy consumption and eliminated thermal expansion variations between the mold, substrate, and resists by accelerating the PDMS curing time to less than 10 min at room temperature without using heat or ultraviolet radiation. The additive manufacturing technology was applied to fabricate a multi-depth flexible polymer mold that integrated macro (2 mm) and micro-sized (500 μm) features, which overcomes the economic and environmental challenges of conventional molding techniques. Our integrated R2R platform was enabled to print adhesion-promoting films at the first printing unit and continuously in-line imprint with a high replication accuracy (99%) for high-volume manufacturing of a new centrifugal microfluidic chip with an enhancement of mixing performance by integrating an efficient mixing chamber and serpentine micromixer. This research paved the way for scalable green manufacturing of large-volume polymer-based microfluidic devices, often required in real-world sample-driven analytical systems for clinical bioanalysis.

Bacteriophage-based biosensors for detection of pathogenic microbes in wastewater

Wastewater is discarded from several sources, including industry, livestock, fertilizer application, and municipal waste. If the disposed of wastewater has not been treated and processed before discharge to the environment, pathogenic microorganisms and toxic chemicals are accumulated in the disposal area and transported into the surface waters. The presence of harmful microbes is responsible for thousands of human deaths related to water-born contamination every year. To be able to take the necessary step and quick action against the possible presence of harmful microorganisms and substances, there is a need to improve the effective speed of identification and treatment of these problems. Biosensors are such devices that can give quantitative information within a short period of time. There have been several biosensors developed to measure certain parameters and microorganisms. The discovered biosensors can be utilized for the detection of axenic and mixed microbial strains from the wastewaters. Biosensors can further be developed for specific conditions and environments with an in-depth understanding of microbial organization and interaction within that community. In this regard, bacteriophage-based biosensors have become a possibility to identify specific live bacteria in an infected environment. This paper has investigated the current scenario of microbial community analysis and biosensor development in identifying the presence of pathogenic microorganisms.

Sample-to-answer sensing technologies for nucleic acid preparation and detection in the field

Efficient sample preparation and accurate disease diagnosis under field conditions are of great importance for the early intervention of diseases in humans, animals, and plants. However, in-field preparation of high-quality nucleic acids from various specimens for downstream analyses, such as amplification and sequencing, is challenging. Thus, developing and adapting sample lysis and nucleic acid extraction protocols suitable for portable formats have drawn significant attention. Similarly, various nucleic acid amplification techniques and detection methods have also been explored. Combining these functions in an integrated platform has resulted in emergent sample-to-answer sensing systems that allow effective disease detection and analyses outside a laboratory. Such devices have a vast potential to improve healthcare in resource-limited settings, low-cost and distributed surveillance of diseases in food and agriculture industries, environmental monitoring, and defense against biological warfare and terrorism. This paper reviews recent advances in portable sample preparation technologies and facile detection methods that have been / or could be adopted into novel sample-to-answer devices. In addition, recent developments and challenges of commercial kits and devices targeting on-site diagnosis of various plant diseases are discussed.

Integrated Plastic Microfluidic Device for Heavy Metal Ion Detection

The presence of heavy metal ions in soil, air and water constitutes an important global environmental threat, as these ions accumulate throughout the food chain, contributing to the rise of chronic diseases, including, amongst others, cancer and kidney failure. To date, many efforts have been made for their detection, but there is still a need for the development of sensitive, low-cost, and portable devices able to conduct on-site detection of heavy metal ions. In this work, we combine microfluidic technology and electrochemical sensing in a plastic chip for the selective detection of heavy metal ions utilizing DNAzymes immobilized in between platinum nanoparticles (PtNPs), demonstrating a reliable portable solution for water pollution monitoring. For the realization of the microfluidic-based heavy metal ion detection device, a fast and easy-to-implement fabrication method based on the photolithography of dry photosensitive layers is proposed. As a proof of concept, we demonstrate the detection of Pb2+ ions using the prototype microfluidic device.

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.

Rapid quantitation of SARS-CoV-2 antibodies in clinical samples with an electrochemical sensor

The current coronavirus disease 2019 (COVID-19) pandemic is caused by several variants of severe acute respiratory syndrome coronavirus-2 virus (SARS-CoV-2). With the roll-out of vaccines and development of new therapeutics that may be targeted to distinct viral molecules, there is a need to screen populations for viral antigen-specific SARS-CoV-2 antibodies. Here, we report a rapid, multiplexed, electrochemical (EC) device with on-chip control that enables detection of SARS-CoV-2 antibodies in less than 10 min using 1.5 μL of a patient sample. The EC biosensor demonstrated 100% sensitivity and specificity, and an area under the receiver operating characteristic curve of 1, when evaluated using 93 clinical samples, including plasma and dried blood spot samples from 54 SARS-CoV-2 positive and 39 negative patients. This EC biosensor platform enables simple, cost-effective, sensitive, and rapid detection of anti-SARS-CoV-2 antibodies in complex clinical samples, which is convenient for evaluating humoral-responses to vaccination or infection in population-wide testing, including applications in point-of-care settings. We also demonstrate the feasibility of using dried blood spot samples that can be collected locally and transported to distant clinical laboratories at ambient temperature for detection of anti-SARS-CoV-2 antibodies which may be utilized for serological surveillance and demonstrate the utility of remote sampling.

Toward waterborne protozoa detection using sensing technologies

Drought and limited sufficient water resources will be the main challenges for humankind during the coming years. The lack of water resources for washing, bathing, and drinking increases the use of contaminated water and the risk of waterborne diseases. A considerable number of waterborne outbreaks are due to protozoan parasites that may remain active/alive in harsh environmental conditions. Therefore, a regular monitoring program of water resources using sensitive techniques is needed to decrease the risk of waterborne outbreaks. Wellorganized point-of-care (POC) systems with enough sensitivity and specificity is the holy grail of research for monitoring platforms. In this review, we comprehensively gathered and discussed rapid, selective, and easy-to-use biosensor and nanobiosensor technologies, developed for the early detection of common waterborne protozoa.

Multiplex Surface-Enhanced Raman Scattering: An Emerging Tool for Multicomponent Detection of Food Contaminants

For survival and quality of human life, the search for better ways to ensure food safety is constant. However, food contaminants still threaten human health throughout the food chain. In particular, food systems are often polluted with multiple contaminants simultaneously, which can cause synergistic effects and greatly increase food toxicity. Therefore, the establishment of multiple food contaminant detection methods is significant in food safety control. The surface-enhanced Raman scattering (SERS) technique has emerged as a potent candidate for the detection of multicomponents simultaneously. The current review focuses on the SERS-based strategies in multicomponent detection, including the combination of chromatography methods, chemometrics, and microfluidic engineering with the SERS technique. Furthermore, recent applications of SERS in the detection of multiple foodborne bacteria, pesticides, veterinary drugs, food adulterants, mycotoxins and polycyclic aromatic hydrocarbons are summarized. Finally, challenges and future prospects for the SERS-based detection of multiple food contaminants are discussed to provide research orientation for further.

Aptamer-functionalised metal-organic frameworks as an 'on-off-on' fluorescent sensor for bisphenol S detection

Bisphenol S (BPS) is an industrial chemical that is widely used to manufacture daily items, such as plastic water bottles, milk bottles, water cups, and paper products. BPS is a biologically toxic environmental endocrine disruptor. Long-term exposure to BPS can disrupt the reproductive system, endanger health, and increase the risk of cancer. The metal-organic framework UiO-66 is characterised with high thermal and chemical stability, a simple synthetic route, and low preparation cost. In this study, we modified UiO-66 with nucleic acid aptamers to prepare an 'on-off-on' fluorescent sensor for the simple and rapid detection of BPS. The FAM-labelled aptamer was selected as the fluorescent probe (i.e. 'on'). In the presence of UiO-66, the FAM-labelled aptamer adsorbed onto the surface of the UiO-66 material, and the fluorescence of FAM was quenched by photoinduced electron transfer (i.e. 'off'). When BPS was introduced into the system, the configuration of the FAM-labelled aptamer changed after binding to BPS, and the adsorption of FAM on UiO-66 weakened, resulting in fluorescence recovery (i.e. 'on'). Based on this principle, the reaction system was optimised, and the BPS content was analysed according to the change in the fluorescence signal. The signals changed linearly in the BPS concentration range of 2.0 × 10^-4-4.0 × 10^-2 mmol L^-1, and the system had a detection limit of 1.84 × 10^-4 mmol L^-1. The sensor was successfully used to detect the BPS content in commercial plastic bottled water.

Biofabrication of Multiplexed Electrochemical Immunosensors for Simultaneous Detection of Clinical Biomarkers in Complex Fluids

Simultaneous detection of multiple disease biomarkers in unprocessed whole blood is considered the gold standard for accurate clinical diagnosis. Here, this study reports the development of a 4-plex electrochemical (EC) immunosensor with on-chip negative control capable of detecting a range of biomarkers in small volumes (15 µL) of complex biological fluids, including serum, plasma, and whole blood. A framework for fabricating and optimizing multiplexed sandwich immunoassays is presented that is enabled by use of EC sensor chips coated with an ultra-selective, antifouling, and nanocomposite coating. Cyclic voltammetry evaluation of sensor performance is carried out by monitoring the local precipitation of an electroactive product generated by horseradish peroxidase linked to a secondary antibody. EC immunosensors demonstrate high sensitivity and specificity without background signal with a limit of detection in single-digit picogram per milliliter in multiple complex biological fluids. These multiplexed immunosensors enable the simultaneous detection of four different biomarkers in plasma and whole blood with excellent sensitivity and selectivity. This rapid and cost-effective biosensor platform can be further adapted for use with different high affinity probes for any biomarker, and thereby create for a new class of highly sensitive and specific multiplexed diagnostics.

Microfluidic platforms integrated with nano-sensors for point-of-care bioanalysis

Microfluidic technology provides a portable, cost-effective, and versatile tool for point-of-care (POC) bioanalysis because of its associated advantages such as fast analysis, low volumes of reagent consumption, and high portability. Along with microfluidics, the application of nanomaterials in biosensing has attracted lots of attention due to their unique physical and chemical properties for enhanced signal modulation such as signal amplification and signal transduction for POC bioanalysis. Hence, an enormous number of microfluidic devices integrated with nano-sensors have been developed for POC bioanalysis targeting low-resource settings. Herein, we review recent advances in POC bioanalysis on nano-sensor-based microfluidic platforms. We first briefly summarized the different types of cost-effective microfluidic platforms, followed by a concise introduction to nanomaterial-based biosensors. Then, we highlighted the application of microfluidic platforms integrated with nano-sensors for POC bioanalysis. Finally, we discussed the current limitations and perspective trends of the nano-sensor-based microfluidic platforms for POC bioanalysis.

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.

Shape-Encoded Functional Hydrogel Pellets for Multiplexed Detection of Pathogenic Bacteria Using a Gas Pressure Sensor

Gas pressure is a promising signal readout mode in point-of-care testing for its merits such as rapidity, simplicity, affordability, and no need for sophisticated instrumentation. Herein, a gas pressure sensor for multiplexed detection of pathogenic bacteria was developed on a hydrogel platform. Spherical and square hydrogel pellets prepared by cross-linking of sodium alginate were functionalized with nisin and ConA for the capture of Staphylococcus aureus and Escherichia coli O157:H7, respectively. By using the shape-encoded functional hydrogel pellets and aptamer-modified platinum-coated gold nanoparticles (Au@PtNPs), a dual-molecule recognition mode was established for rapid and specific detection of the two pathogenic bacteria. Au@PtNPs were applied as signal probes to efficiently catalyze the decomposition of H₂O₂ for generating abundant O₂, which was converted into an amplified gas pressure signal. In two closed containers, the significant gas pressure signals were monitored with a portable pressure meter to quantitate the two pathogenic bacteria. The sensor was successfully applied to detect the pathogenic bacteria in various environmental, biological, and food samples. Thus, the proof-of-principle work paves a new avenue for multiplexed detection of pathogenic bacteria with shape-encoded hydrogel pellets combined with gas pressure signal readout.

Harnessing the Potential of Biological Recognition Elements for Water Pollution Monitoring

Environmental monitoring of pollutants is an imperative first step to remove the genotoxic, embryotoxic, and carcinogenic toxins. Various biological sensing elements such as proteins, aptamers, whole cells, etc., have been used to track down major pollutants, including heavy metals, aromatic pollutants, pathogenic microorganisms, and pesticides in both environmental samples and drinking water, demonstrating their potential in a true sense. The intermixed use of nanomaterials, electronics, and microfluidic systems has further improved the design and enabled robust on-site detection with enhanced sensitivity. Through this perspective, we shed light on the advances in the field and entail recent efforts to optimize these systems for real-time, online sensing and on-site field monitoring.

A Specific Mass-Tag Approach for Detection of Foodborne Pathogens Using MALDI-TOF Mass Spectrometry

Pathogen infections present a considerable threat to global health owing to the high morbidity and mortality, and usually multiple pathogens coexist in food and the environment. Consequently, it is in urgent need to develop some multiplexed and sensitive approaches for pathogen detection. Here, we presented a novel strategy using mass tag-mediated surface engineering for simultaneous detection of multiple bacteria by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Following aptamer binding, primer amplification, and DNA hybridization, bacteria were specifically labeled by their corresponding mass tags, which could be released and ionized after laser irradiation. This strategy converted the detection of bacteria to the analysis of mass tags, allowing simultaneous detection of multiple bacteria and avoiding the dependence of microbial mass spectra databases. In addition, this approach applied two rolling circle amplification (RCA) reactions to improve both the capture efficiency and detection sensitivity of the target bacteria. The specificity and the real sample detection were evaluated, and the results demonstrated a potential application of this approach in milk safety monitoring.

Multiplex optical bioassays for food safety analysis: Toward on-site detection

Food safety analysis plays a significant role in controlling food contamination and supervision. In recent years, multiplex optical bioassays (MOBAs) have been widely applied to analyze multiple hazards due to their efficiency and low cost. However, due to the challenges such as multiplexing capacity, poor sensitivity, and bulky instrumentation, the further application of traditional MOBAs in food screening has been limited. In this review, effective strategies regarding food safety MOBAs are summarized, such as spatial-resolution modes performed in multi-T lines/dots strips or arrays of strip/microplate/microfluidic chip/SPR chip and signal-resolution modes employing distinguishable colorimetric/luminescence/fluorescence/surface plasma resonance/surface-enhanced Raman spectrum as signal tags. Following this, new trends on how to design engineered sensor architecture and exploit distinguishable signal reporters, how to improve both multiplexing capacity and sensitivity, and how to integrate these formats into smartphones so as to be mobile are summarized systematically. Typically, in the case of enhancing multiplexing capacity and detection throughput, microfluidic array chips with multichannel architecture would be a favorable approach to overcome the spatial and physical limitations of immunochromatographic assay (ICA) test strips. Moreover, noble metal nanoparticles and single-excitation, multiple-emission luminescence nanomaterials hold great potential in developing ultrasensitive MOBAs. Finally, the exploitation of innovative multiplexing strategy hybridized with powerful and widely available smartphones opens new perspectives to MOBAs. In future, the MOBAs should be more sensitive, have higher multiplexing capacity, and easier instrumentation.

Applications of biosensors for bacteria and virus detection in food and water-A systematic review

Biosensors for sensitive and specific detection of foodborne and waterborne pathogens are particularly valued for their portability, usability, relatively low cost, and real-time or near real-time response. Their application is widespread in several domains, including environmental monitoring. The main limitation of currently developed biosensors is a lack of sensitivity and specificity in complex matrices. Due to increased interest in biosensor development, we conducted a systematic review, complying with the PRISMA guidelines, covering the period from January 2010 to December 2019. The review is focused on biosensor applications in the identification of foodborne and waterborne microorganisms based on research articles identified in the Pubmed, ScienceDirect, and Scopus search engines. Efforts are still in progress to overcome detection limitations and to provide a rapid detection system which will safeguard water and food quality. The use of biosensors is an essential tool with applicability in the evaluation and monitoring of the environment and food, with great impact in public health.

Aptasensors for the detection of infectious pathogens: design strategies and point-of-care testing

The epidemic of infectious diseases caused by contagious pathogens is a life-threatening hazard to the entire human population worldwide. A timely and accurate diagnosis is the critical link in the fight against infectious diseases. Aptamer-based biosensors, the so-called aptasensors, employ nucleic acid aptamers as bio-receptors for the recognition of target pathogens of interest. This review focuses on the design strategies as well as state-of-the-art technologies of aptasensor-based diagnostics for infectious pathogens (mainly bacteria and viruses), covering the utilization of three major signal transducers, the employment of aptamers as recognition moieties, the construction of versatile biosensing platforms (mostly micro and nanomaterial-based), innovated reporting mechanisms, and signal enhancement approaches. Advanced point-of-care testing (POCT) for infectious disease diagnostics are also discussed highlighting some representative ready-to-use devices to address the urgent needs of currently prevalent coronavirus disease 2019 (COVID-19). Pressing issues in aptamer-based technology and some future perspectives of aptasensors are provided for the implementation of aptasensor-based diagnostics into practical application.

Colorimetric determination of Listeria monocytogenes using aptamer and urease dual-labeled magnetic nanoparticles and cucurbit[7]uril-mediated supramolecular assembly of gold nanoparticle

A host-guest colorimetric strategy is described for the detection of Listeria monocytogenes (L. monocytogenes). The optical probes were self-assembled based on the supramolecular interactions between the carbonyl groups of cucurbit[7]uril portals and gold nanoparticles (CB[7]-AuNPs). Aptamer and urease modified magnetic nanoparticles were used to specifically recognize and binding to L. monocytogenes, simultaneously hydrolyzing urea to produce ammonium ion (NH₄⁺) that can reverse CB[7] induced AuNPs aggregation. In the presence of L. monocytogenes, the above-mentioned magnetic conjugates preferentially bind to the bacterial surface, which results in blocking the catalytic active sites, thus inhibiting the production of ammonium ions. The normalized absorbance ratio of A_{700 nm}/A_{525 nm} was proportional to the L. monocytogenes concentration ranging from 10 to 10⁶ cfu·mL^-1, and the visual determination can be done down to 10 cfu·mL^-1. For spiked food samples analyzed without pre-enrichment, recoveries of 98.4% to 99.3% were achieved could be verified and RSD were less than 10%. This work may offer a broad prospect for sensitive and specific determination  of pathogens.

Integration and Quantitative Visualization of 3,3',5,5'-Tetramethylbenzidine-Probed Enzyme-Linked Immunosorbent Assay-like Signals in a Photothermal Bar-Chart Microfluidic Chip for Multiplexed Immunosensing

The photothermal effect shows significant promise for various biomedical applications but is rarely exploited for microfluidic lab-on-a-chip bioassays. Herein, a photothermal bar-chart microfluidic immunosensing chip, with the integration of the conventional 3,3',5,5'-tetramethylbenzidine (TMB)-probed enzyme-linked immunosorbent assay (ELISA)-like system, was developed based on exploiting the photothermal pumping technique for visual bar-chart microfluidic immunosensing. Both the sandwich ELISA-like system and the photothermal pumping protocol were integrated into a single photothermal bar-chart chip. On-chip immunocaptured iron oxide nanoparticles catalyzed the oxidation of the chromogenic substrate, TMB, to produce a sensitive photothermal and chromogenic dual-functional probe, oxidized TMB. As the result of heat generation and the subsequent production of elevating vapor pressure in the sealed microfluidic environment, the on-chip near-infrared laser-driven photothermal effect of the probe served as a dose-dependent pumping force to drive the multiplexed quantitative display of the immunosensing signals as visual dye bar charts. Prostate-specific antigen as a model analyte was tested at a limit of detection of 1.9 ng·mL^-1, lower than the clinical diagnostic threshold of prostate cancer. This work presents a new perspective for microfluidic integration and multiplexed quantitative bar-chart visualization of the conventional TMB-probed ELISA signals possibly by means of an affordable handheld laser pointer in a lab-on-a-chip format.

A digitalized isothermal nucleic acid testing platform based on a pump-free open droplet array microfluidic chip

Digital PCR has shown great potential for quantitative nucleic acid testing (NAT), but most existing platforms are dependent on large auxiliary equipment (e.g., vacuum pump, amplification instrument, fluorescence microscope) to achieve target dispersion, amplification, signal capture and result analysis. Such complex, expensive and bulky NAT platforms have limited their applications in resource-limited areas, especially for point-of-care testing (POCT). In this work, we designed a digital isothermal NAT platform based on a pump-free open droplet array microfluidic chip. A pump-free microfluidic chip was developed based on an open microdroplet array in the form of thousands of independent microdroplets for spontaneous sample dispersion, without the need for external power. Combined with a handheld fluorescent signal reader based on a smartphone, this digital NAT platform can accurately quantify as low as 1 copy per μL of λDNA. Therefore, our integrated NAT platform, as a potable, robust and low-cost tool for highly accurate NA quantitative analysis, holds great potential for POCT applications.

Nanomedicine as a promising strategy for the theranostics of infectious diseases

Infectious diseases caused by bacteria, viruses, and fungi and their global spread pose a great threat to human health. The 2019 World Health Organization report predicted that infection-related mortality will be similar to cancer mortality by 2050. Particularly, the global cumulative numbers of the recent outbreak of coronavirus disease (COVID-19) have reached 110.7 million cases and over 2.4 million deaths as of February 23, 2021. Moreover, the crisis of these infectious diseases exposes the many problems of traditional diagnosis, treatment, and prevention, such as time-consuming and unselective detection methods, the emergence of drug-resistant bacteria, serious side effects, and poor drug delivery. There is an urgent need for rapid and sensitive diagnosis as well as high efficacy and low toxicity treatments. The emergence of nanomedicine has provided a promising strategy to greatly enhance detection methods and drug treatment efficacy. Owing to their unique optical, magnetic, and electrical properties, nanoparticles (NPs) have great potential for the fast and selective detection of bacteria, viruses, and fungi. NPs exhibit remarkable antibacterial activity by releasing reactive oxygen species and metal ions, exerting photothermal effects, and causing destruction of the cell membrane. Nano-based delivery systems can further improve drug permeability, reduce the side effects of drugs, and prolong systemic circulation time and drug half-life. Moreover, effective drugs against COVID-19 are still lacking. Recently, nanomedicine has shown great potential to accelerate the development of safe and novel anti-COVID-19 drugs. This article reviews the fundamental mechanisms and the latest developments in the treatment and diagnosis of bacteria, viruses, and fungi and discusses the challenges and perspectives in the application of nanomedicine.

Nanomaterials in the Management of Gram-Negative Bacterial Infections

The exploration of multiplexed bacterial virulence factors is a major problem in the early stages of Escherichia coli infection therapy. Traditional methods for detecting Escherichia coli (E. coli), such as serological experiments, immunoassays, polymerase chain reaction, and isothermal microcalorimetry have some drawbacks. As a result, detecting E. coli in a timely, cost-effective, and sensitive manner is critical for various areas of human safety and health. Intelligent devices based on nanotechnology are paving the way for fast and early detection of E. coli at the point of care. Due to their specific optical, magnetic, and electrical capabilities, nanostructures can play an important role in bacterial sensors. Another one of the applications involved use of nanomaterials in fighting microbial infections, including E. coli mediated infections. Various types of nanomaterials, either used directly as an antibacterial agent such as metallic nanoparticles (NPs) (silver, gold, zinc, etc.), or as a nanocarrier to deliver and target the antibiotic to the E. coli and its infected area. Among different types, polymeric NPs, lipidic nanocarriers, metallic nanocarriers, nanomicelles, nanoemulsion/ nanosuspension, dendrimers, graphene, etc. proved to be effective vehicles to deliver the drug in a controlled fashion at the targeted site with lower off-site drug leakage and side effects.

Sequestration and Removal of Multiple Small-Molecule Contaminants Using an Optimized Aptamer-Based Ultrafiltration System

Small-molecule toxins pose a significant threat to human health and the environment, and their removal is made challenging by their low molecular weight. Aptamers show promise as affinity reagents for binding these toxins, and recently, aptamers have been utilized for both sensing and remediation applications. We found that functionalization of ultrafiltration membranes with aptamers provides a convenient scaffold for toxin sequestration, but our initial efforts in this area were limited by low functionalization efficiencies and the ability to only capture a single target molecule. Herein, we describe detailed optimization of our aptamer-functionalized ultrafiltration membrane system and subsequent use for simultaneous removal of multiple small-molecule toxins. We examine multiple critical components involved in fabricating and functionalizing the membranes, including PEG polymer molecular weight for membrane fabrication, grafting conditions for pMAA attachment, and coupling reagents for aptamer functionalization. This screening enabled us to identify a set of unique conditions in which we were able to achieve high flux, near quantitative yield for DNA attachment, and effective overall depletion of both toxins and bacterial cells. Furthermore, we demonstrate the attachment of multiple aptamers and subsequent parallel removal of atrazine, bisphenol A, and microcystin-LR in a complex lake water matrix. Our rigorous evaluation resulted in depletion of multiple small-molecule toxins, contaminants, and microorganisms, demonstrating the potential of aptamer-functionalized membranes as point-of-use decontamination systems.

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.

Functional Micro-/Nanomaterials for Multiplexed Biodetection

When analyzing biological phenomena and processes, multiplexed biodetection has many advantages over single-factor biodetection and is highly relevant to both human health issues and advancements in the life sciences. However, many key problems with current multiplexed biodetection strategies remain unresolved. Herein, the main issues are analyzed and summarized: 1) generating sufficient signal to label targets, 2) improving the signal-to-noise ratio to ensure total detection sensitivity, and 3) simplifying the detection process to reduce the time and labor costs of multiple target detection. Then, available solutions made possible by designing and controlling the properties of micro- and nanomaterials are introduced. The aim is to emphasize the role that micro-/nanomaterials can play in the improvement of multiplexed biodetection strategies. Through analyzing existing problems, introducing state-of-the-art developments regarding relevant materials, and discussing future directions of the field, it is hopeful to help promote necessary developments in multiplexed biodetection and associated scientific research.

Size-Resolved Single Entity Collision Biosensing for Dual Quantification of MicroRNAs in a Single Run

Limited to the accuracy of size resolution, single entity collision biosensing (SECBS) for multiplex immunoassays remains challenging, because it is difficult to get the true value of nanoparticle (NP) sizes based on the current intensity due to the complex movement of NPs on the electrode surface. Considering that the size-dependent movement of NPs meanwhile will generate a characteristic current shape, in this work, the huge difference in the current rise time of 5 and 15 nm Pt NPs colliding on an Au ultramicroelectrode (d = 30 μm) was originally used to develop a size-resolved SECBS for multiplex immunoassays of miRNAs. The limit concentration that can be detected was 0.5 fM. Compared with conventional electrochemical biosensors for multiplex immunoassays, for the size-resolved SECBS, one does not need to worry about potential overlapping. Therefore, the proposed method demonstrates a promising potential for the application of SECBS in multiplex immunoassays.

Detector-Free Photothermal Bar-Chart Microfluidic Chips (PT-Chips) for Visual Quantitative Detection of Biomarkers

The volumetric bar-chart microfluidic chips (V-Chips) driven by chemical reaction-generated gas provide a promising platform for point-of-care (POC) visual biomarker quantitation. However, multiple limitations are encountered in conventional V-Chips, such as costly and complex chip fabrication, complicated chip assembly, and imprecise controllability of gas production. Herein, we introduced nanomaterial-mediated photothermal effects to V-Chips, and for the first time developed a new type of V-Chip, photothermal bar-chart microfluidic chip (PT-Chip), for visual quantitative detection of biochemicals without any bulky and costly analytical instruments. Immunosensing signals were converted to visual readout signals via photothermal effects, the on-chip bar-chart movements, enabling quantitative biomarker detection on a low-cost polymer hybrid PT-Chip with on-chip scale rulers. Four different human serum samples containing a prostate-specific antigen (PSA) as a model analyte were detected simultaneously using the PT-Chip, with a limit of detection of 2.1 ng/mL, meeting clinical diagnostic requirements. Although no conventional signal detectors were used, it achieved comparable detection sensitivity to absorbance measurements with a microplate reader. The PT-Chip was further validated by testing human whole blood without the color interference problem, demonstrating the good analytical performance of our method even in complex matrices and thus the potential to fill the gap in current clinical diagnostics that is incapable of testing whole blood. This new PT-Chip driven by nanomaterial-mediated photothermal effects opens a new horizon of microfluidic platforms for instrument-free diagnostics at the point-of-care.

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.

Multichannel Paper Chip-Based Gas Pressure Bioassay for Simultaneous Detection of Multiple MicroRNAs

Simultaneous detection of multi-biomarkers not only enhances the accuracy of disease diagnosis but also improves detection efficiency and reduces cost. It is vital to achieve portable, simple, low-cost, and simultaneous detection of biomarkers for point-of-care (POC) diagnostics in a low-resource setting. Herein, a multichannel paper chip-based gas pressure bioassay was developed for the simultaneous detection of multiple biomarkers by combining multichannel paper chips with a portable gas pressure meter. Four DNA tetrahedral probes (DTPs) were used as capture probes and were immobilized in different detection zones of the paper chips to improve hybridization efficiency and reduce nonspecific adsorption. The formation of a sandwich structure between target microRNAs (miRNAs), the capture probe, and platinum nanoparticles (PtNPs)-modified complementary DNA (PtNPs-cDNA) transformed biomolecular recognition into quantitative detection of gas pressure. Four lung cancer-related miRNAs were detected simultaneously by a portable gas pressure meter. There is a good linear relationship between gas pressure and the logarithm of miRNA concentration in the range of 10 pM to 100 nM. Compared with single-stranded DNA capture probe, the signal-to-noise (S/N) of DNA tetrahedral probes improved more than 3 times. Using ring-oven washing, the unbound reagents in all channels of the paper chip were simultaneously and continuously washed away, leading to a more cheap, simple, and fast separation than magnetic separation. Therefore, it offers a promising multichannel paper chip-based gas pressure bioassay for portable and simultaneous detection of multiple biomarkers.

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.

Aptamer-Functionalized Hybrid Nanostructures for Sensing, Drug Delivery, Catalysis and Mechanical Applications

Sequence-specific nucleic acids exhibiting selective recognition properties towards low-molecular-weight substrates and macromolecules (aptamers) find growing interest as functional biopolymers for analysis, medical applications such as imaging, drug delivery and even therapeutic agents, nanotechnology, material science and more. The present perspective article introduces a glossary of examples for diverse applications of aptamers mainly originated from our laboratory. These include the introduction of aptamer-functionalized nanomaterials such as graphene oxide, Ag nanoclusters and semiconductor quantum dots as functional hybrid nanomaterials for optical sensing of target analytes. The use of aptamer-functionalized DNA tetrahedra nanostructures for multiplex analysis and aptamer-loaded metal-organic framework nanoparticles acting as sense-and-treat are introduced. Aptamer-functionalized nano and microcarriers are presented as stimuli-responsive hybrid drug carriers for controlled and targeted drug release, including aptamer-functionalized SiO2 nanoparticles, carbon dots, metal-organic frameworks and microcapsules. A further application of aptamers involves the conjugation of aptamers to catalytic units as a means to mimic enzyme functions "nucleoapzymes". In addition, the formation and dissociation of aptamer-ligand complexes are applied to develop mechanical molecular devices and to switch nanostructures such as origami scaffolds. Finally, the article discusses future challenges in applying aptamers in material science, nanotechnology and catalysis.

Cancer cell enrichment on a centrifugal microfluidic platform using hydrodynamic and magnetophoretic techniques

Isolation of rare cancer cells is one of the important and valuable stages of cancer research. Regarding the rarity of cancer cells in blood samples, it is important to invent an efficient separation device for cell enrichment. In this study, two centrifugal microfluidic devices were designed and fabricated for the isolation of rare cancer cells. The first design (passive plan) employs a contraction–expansion array (CEA) microchannel which is connected to a bifurcation region. This device is able to isolate the target cells through inertial effects and bifurcation law. The second design (hybrid plan) also utilizes a CEA microchannel, but instead of using the bifurcation region, it is reinforced by a stack of two permanent magnets to capture the magnetically labeled target cells at the end of the microchannel. These designs were optimized by numerical simulations and tested experimentally for isolation of MCF-7 human breast cancer cells from the population of mouse fibroblast L929 cells. In order to use the hybrid design, magnetite nanoparticles were attached to the MCF-7 cells through specific Ep-CAM antibodies, and two permanent magnets of 0.34 T were utilized at the downstream of the CEA microchannel. These devices were tested at different disk rotational speeds and it was found that the passive design can isolate MCF-7 cells with a recovery rate of 76% for the rotational speed of 2100 rpm while its hybrid counterpart is able to separate the target cells with a recovery rate of 85% for the rotational speed of 1200 rpm. Although the hybrid design of separator has a better separation efficiency and higher purity, the passive one has no need for a time-consuming process of cell labeling, occupies less space on the disk, and does not impose additional costs and complexity.

Novel porous ceramic sheet supported metal reactors for continuous-flow catalysis

A novel porous ceramic sheet supported nickel particles reactor was obtained by an in-situ preparation method. This reactor was then used to investigate continuous-flow catalysis of nitroaromatic compounds and methyl orange. The details of the structure and morphology were characterized by XRD, SEM, XPS, Raman, element mapping, mercury intrusion method and Archimedes principle. The porous ceramic sheet supported Ni particles reactor exhibited excellent catalytic performance in the catalytic reduction of p-nitrophenol and methyl orange by sodium borohydride at room temperature. Both the conversion of p-nitrophenol (5 mM) and methyl orange (0.3 mM) reached nearly 100% at the injection speed of 2.67 mL·min^-1. In addition, it maintained conversions of 100% after 10 recycling time since the porous ceramic sheet could reduce the aggregation for Ni particles. Furthermore, the chemisorbed oxygen, and the strong interaction between Ni and porous ceramic sheet resulted in a highly efficient, recoverable, and cost-effective multifunctional reactor. All of these advantages present new opportunities to be implemented in the field of waste water treatment and environmental toxicology. Ultimately, the porous ceramic sheet could also support other metal nanomaterial, and used in other fields of environmental catalysis.

Advances in detection of infectious agents by aptamer-based technologies

Infectious diseases still remain one of the biggest challenges for human health. Accurate and early detection of infectious pathogens are crucial for transmission control, clinical diagnosis, and therapy. For a traditional reason, most immunological and microbiological laboratories are equipped with instruments designated for antibody-based assays in detection of infectious pathogens or clinical diagnosis. Emerging aptamer-based technologies have pushed a shift from antibody-based to aptamer-based assays due to equal specificity, even better sensitivity, lower manufacturing cost and more flexibility in amending for chemiluminescent, electrochemical or fluorescent detection in a multifaceted and high throughput fashion in comparison of aptamer-based to antibody-based assays. The nature of aptamer-based technologies is particularly suitable for point-of-care testing in remote areas at warm or hot atmosphere, and mass screening for potential infection in pandemic of emerging infectious agents, such as SARS-CoV or SARS-CoV-2 in an epicentre or other regions. This review intends to summarize currently available aptamer-based technologies in detection of bacterial, viral, and protozoan pathogens for research and clinical application. It is anticipated that potential technologies will be further optimized and validated for clinical translation in meeting increasing demands for prompt, precise, and reliable detection of specific pathogens in various atmospheric conditions.

Strong interaction between Au nanoparticles and porous polyurethane sponge enables efficient environmental catalysis with high reusability

A novel and recoverable platform of polyurethane (PU) sponge-supported Au nanoparticle catalyst was obtained by a water-based in-situ preparation process. The structure, chemical, and morphology properties of this platform were characterized by XRD, TGA, SEM, FT-IR, and XPS. The Au/PU sponge platform exhibited excellent catalytic performances in catalytic reductions of p-nitrophenol and o-nitroaniline at room temperature, and both catalytic reactions could be completed within 4.5 and 1.5 min, respectively. Furthermore, the strong interaction between Au nanoparticles and the PU sponge enabled the catalyst system to maintain a high catalytic efficiency after 5 recycling times, since the PU sponge reduced the trend of leaching and aggregation of Au nanoparticles. The unique nature of Au nanoparticles and the porous PU sponge along with their strong interaction resulted in a highly efficient, recoverable, and cost-effective multifunctional catalyst. The AuNP/Sponge nanocatalyst platform has great potential for wide environmental and other catalytic applications.

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.

Biosensors for rapid detection of Salmonella in food: A review

Salmonella is one of the main causes of foodborne infectious diseases, posing a serious threat to public health. It can enter the food supply chain at various stages of production, processing, distribution, and marketing. High prevalence of Salmonella necessitates efficient and effective approaches for its identification, detection, and monitoring at an early stage. Because conventional methods based on plate counting and real-time polymerase chain reaction are time-consuming and laborious, novel rapid detection methods are urgently needed for in-field and on-line applications. Biosensors provide many advantages over conventional laboratory assays in terms of sensitivity, specificity, and accuracy, and show superiority in rapid response and potential portability. They are now recognized as promising alternative tools and one of the most on-site applicable and end user-accessible methods for rapid detection. In recent years, we have witnessed a flourishing of studies in the development of robust and elaborate biosensors for detection of Salmonella in food. This review aims to provide a comprehensive overview on Salmonella biosensors by highlighting different signal-transducing mechanisms (optical, electrochemical, piezoelectric, etc.) and critically analyzing its recent trends, particularly in combination with nanomaterials, microfluidics, portable instruments, and smartphones. Furthermore, current challenges are emphasized and future perspectives are discussed.

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.