Power-free chip enzyme immunoassay for detection of prostate specific antigen (PSA) in serum

Cu2O@PdAg-quenched CdS@CeO2 heterostructure electrochemiluminescence immunosensor for determination of prostate-specific antigen

Based on the resonance energy transfer between CdS@CeO₂ and Cu₂O@PdAg, a quenching immunosensor for sensitive detection of prostate specific antigen (PSA) was constructed. The CdS@CeO₂ heterostructure was obtained by in situ growth of CeO₂ particles on the surface of CdS nanorods, and stable cathodic ECL emission was achieved using K₂S₂O₈ as coreactant. Cu₂O@PdAg was composed of Cu₂O with tetradecahedral structure and bimetallic PdAg nanospheres and has a UV-V is absorption range between 600 and 800 nm. It overlaps with the ECL emission spectrum of CdS@CeO₂, realizing the effective quenching of the ECL signal, which provides feasibility for subsequent practical application. The immunosensor exhibited good linearity in the concentration range 10 fg·mL^-1 ~ 100 ng·mL^-1, with a detection limit of 5.6 fg·mL^-1. In sample analysis, the recoveries were 99.8-101%, and the relative standard deviation (RSD) was 0.85-1.6% showing great potential and development value for the sensitive detection of prostate cancer.

Integration of Power-Free and Self-Contained Microfluidic Chip with Fiber Optic Particle Plasmon Resonance Aptasensor for Rapid Detection of SARS-CoV-2 Nucleocapsid Protein

The global pandemic of COVID-19 has created an unrivalled need for sensitive and rapid point-of-care testing (POCT) methods for the detection of infectious viruses. For the novel coronavirus SARS-CoV-2, the nucleocapsid protein (N-protein) is one of the most abundant structural proteins of the virus and it serves as a useful diagnostic marker for detection. Herein, we report a fiber optic particle plasmon resonance (FOPPR) biosensor which employed a single-stranded DNA (ssDNA) aptamer as the recognition element to detect the SARS-CoV-2 N-protein in 15 min with a limit of detection (LOD) of 2.8 nM, meeting the acceptable LOD of 10⁶ copies/mL set by the WHO target product profile. The sensor chip is a microfluidic chip based on the balance between the gravitational potential and the capillary force to control fluid loading, thus enabling the power-free auto-flowing function. It also has a risk-free self-contained design to avoid the risk of the virus leaking into the environment. These findings demonstrate the potential for designing a low-cost and robust POCT device towards rapid antigen detection for early screening of SARS-CoV-2 and its related mutants.

A Portable Biosensor Based on Au Nanoflower Interface Combined with Electrochemical Immunochromatography for POC Detection of Prostate-Specific Antigen

Serum prostate-specific antigen (PSA) is a widely used for the detection of prostate cancer and is considered the most reliable biomarker. However, the currently reported detection methods cannot achieve rapid monitoring. Here, we report a novel electrochemical immunochromatography (EIC) system for clinically accurate PSA detection. First, we constructed a carbon interface modified with gold nanoflowers (Au NFs) based on screen-printed carbon electrodes (SPCE), which acted as nanostructures with larger specific surface area that increased the number of PSA capture antibodies and can further improve detection signal-to-noise (S/N) ratio. Then, we fabricated detection chips by combining the SPCE/Au NFs with EIC. Under optimized conditions, the proposed biosensor exhibits high accuracy, taking only 15 minutes to complete detection. By measuring the levels of PSA in clinical blood samples, the biosensor can successfully discriminate clinically diagnosed prostate cancer patients from healthy controls.

Optical-Based Biosensors and Their Portable Healthcare Devices for Detecting and Monitoring Biomarkers in Body Fluids

The detection and monitoring of biomarkers in body fluids has been used to improve human healthcare activities for decades. In recent years, researchers have focused their attention on applying the point-of-care (POC) strategies into biomarker detection. The evolution of mobile technologies has allowed researchers to develop numerous portable medical devices that aim to deliver comparable results to clinical measurements. Among these, optical-based detection methods have been considered as one of the common and efficient ways to detect and monitor the presence of biomarkers in bodily fluids, and emerging aggregation-induced emission luminogens (AIEgens) with their distinct features are merging with portable medical devices. In this review, the detection methodologies that use optical measurements in the POC systems for the detection and monitoring of biomarkers in bodily fluids are compared, including colorimetry, fluorescence and chemiluminescence measurements. The current portable technologies, with or without the use of smartphones in device development, that are combined with optical biosensors for the detection and monitoring of biomarkers in body fluids, are also investigated. The review also discusses novel AIEgens used in the portable systems for the detection and monitoring of biomarkers in body fluid. Finally, the potential of future developments and the use of optical detection-based portable devices in healthcare activities are explored.

Turntable Paper-Based Device to Detect Escherichia coli

Escherichia coli has been known to cause a variety of infectious diseases. The conventional enzyme-linked immunosorbent assay (ELISA) is a well-known method widely used to diagnose a variety of infectious diseases. This method is expensive and requires considerable time and effort to conduct and complete multiple integral steps. We previously proposed the use of paper-based ELISA to rapidly detect the presence of E. coli. This approach has demonstrated utility for point-of-care (POC) urinary tract infection diagnoses. Paper-based ELISA, while advantageous, still requires the execution of several procedural steps. Here, we discuss the design and experimental implementation of a turntable paper-based device to simplify the paper-based ELISA protocols for the detection of E. coli. In this process, antibodies or reagents are preloaded onto zones of a paper-based device and allowed to dry before use. We successfully used this device to detect E. coli with a detection limit of 10⁵ colony-forming units (colony-forming unit [CFU])/mL.

DNA tetrahedron-mediated immune-sandwich assay for rapid and sensitive detection of PSA through a microfluidic electrochemical detection system

Prostate-specific antigen (PSA) is the most widely used biomarker for the early diagnosis of prostate cancer. Existing methods for PSA detection are burdened with some limitations and require improvement. Herein, we developed a novel microfluidic-electrochemical (μFEC) detection system for PSA detection. First, we constructed an electrochemical biosensor based on screen-printed electrodes (SPEs) with modification of gold nanoflowers (Au NFs) and DNA tetrahedron structural probes (TSPs), which showed great detection performance. Second, we fabricated microfluidic chips by DNA TSP-Au NF-modified SPEs and a PDMS layer with designed dense meandering microchannels. Finally, the μFEC detection system was achieved based on microfluidic chips integrated with the liquid automatic conveying unit and electrochemical detection platform. The μFEC system we developed acquired great detection performance for PSA detection in PBS solution. For PSA assays in spiked serum samples of the μFEC system, we obtained a linear dynamic range of 1-100 ng/mL with a limit of detection of 0.2 ng/mL and a total reaction time <25 min. Real serum samples of prostate cancer patients presented a strong correlation between the "gold-standard" chemiluminescence assays and the μFEC system. In terms of operation procedure, cost, and reaction time, our method was superior to the current methods for PSA detection and shows great potential for practical clinical application in the future.

Self-powered cathodic photoelectrochemical aptasensor based on in situ-synthesized CuO-Cu2O nanowire array for detecting prostate-specific antigen

A facile and sensitive self-powered cathodic photoelectrochemical (PEC) aptasensor is reported for the detection of prostate-specific antigen (PSA) based on CuO-Cu₂O nanowire array grown on Cu mesh (CuO-Cu₂O NWA/CM) as electrode. The mixed narrow band gaps of the CuO-Cu₂O heterostructure ensured its wide absorption band, effective electron/hole separation, and high photocatalytic activity in the visible region. In addition, nanowires directly grown on the substrate provided high specific surface area and exposed abundant active sites, thus guaranteeing its high photocatalytic efficiency. Therefore, the self-powered sensor exhibited favorable analytical performance with fast response, wide linear ranges of 0.01 to 5 ng/mL and 5 to 100 ng/mL, an acceptable detection limit of 3 pg/mL, and reasonable selectivity and stability. The proposed CuO-Cu₂O NWA/CM can be considered a promising visible light-responsive photoactive material for fabrication of PEC aptasensor with high performance. Graphical abstract a Schematic illustration of construction process of PEC sensing platform based on the CuO-Cu₂O composite for PSA detection. b Schematic mechanism of the operating PEC system.

A novel split mode TFBAR device for quantitative measurements of prostate specific antigen in a small sample of whole blood

Easy monitoring of prostate specific antigen (PSA) directly from blood samples would present a significant improvement as compared to conventional diagnostic methods. In this work, a split mode thin film bulk acoustic resonator (TFBAR) device was employed for the first time for label-free measurements of PSA concentrations in the whole blood and without sample pre-treatment. The surface of the sensor was covalently modified with anti-PSA antibodies and demonstrated a very high sensitivity of 101 kHz mL ng^-1 and low limit of detection (LOD) of 0.34 ng mL^-1 in model spiked solutions. It has previously been widely believed that significant pre-processing of blood samples would be required for TFBAR biosensors. Importantly, this work demonstrates that this is not the case, and TFBAR technology provides a cost-effective means for point-of-care (POC) diagnostics and monitoring of PSA in hospitals and in doctors' offices. Additionally, the accuracy of the developed biosensor, with respect to a commercial auto analyser (Beckman Coulter Access), was evaluated to analyse clinical samples, giving well-matched results between the two methods, thus showing a practical application in quantitative monitoring of PSA levels in the whole blood with very good signal recovery.

Pipetting-based immunoassay for point-of-care testing: Application for detection of the influenza A virus

Point-of-care tests (POCT) for pathogens are considered important for low-resource countries and facilities. Although lateral flow immunoassays (LFIA) have many advantages including speed and ease of use, their sensitivity is limited without specific equipment. Furthermore, their response cannot be enhanced through enzymatic reactions. Owing to these limitations, LFIAs have not yet been generally adopted as the standard protocol for in vitro analysis of infectious pathogens. We aimed to develop a novel pipetting-based immunoassay using a removable magnetic ring-coupled pipette tip. The “magnetic bead-capture antibody-targeted protein complex” was simply purified by pipetting and quantified by enzymatic colour development or using a lateral flow system. This pipetting-based immunoassay was applied to detect the nucleoprotein (NP) of the influenza A virus. Using an HRP-conjugated monoclonal antibody as a probe, the assay allowed for specific and sensitive detection. Furthermore, when this assay was applied exclusively for antigen capture in the lateral flow system, the limit of detection improved 100-fold and displayed greater sensitivity than the lateral flow system alone. Therefore, the pipetting-based immunoassay may be potentially used as a sensitive POCT to clinically detect a target antigen.

Copper(II) 1,4-naphthalenedicarboxylate on copper foam nanowire arrays for electrochemical immunosensing of the prostate specific antigen

Nanowires of copper(II)-based metal-organic frameworks (Cu-MOFs) of type Cu(II)(1,4-naphthalenedicarboxylic acid) (1,4-NDC) were deposited on the surface of a copper foam by immersion of Cu(OH)₂ nanowires in a solution of 1,4-NDC. An electrochemical immunosensor for the prostate specific antigen (PSA) is obtained by using the nanowire arrays as a redox signal probe. The signal is generated by the conversion of Cu(I) and Cu(II) of Cu-MOFs nanowires. Cu(1,4-NDC) nanowires contain many uncoordinated carboxyl groups which can bind to the amino groups of the PSA antibody. When PSA antibody binds to PSA antigen during an immune response, the current signal will decrease due to the electrical insulation of PSA antigen. The decrease of current is directly proportional to the increase of PSA concentration. The immunosensor, best operated at a voltage of typically -0.08 V (vs. Ag/AgCl), has a low limit of detection (4.4 fg·mL^-1) and a wide linear range (0.1 pg·mL^-1 to 20 ng·mL^-1). This meets the demands of clinical diagnosis (with values <4 ng·mL^-1) in serum. The method was applied to the determination of PSA in spiked serum. Graphical abstractSchematic representation of the in-situ growth of ordered Cu-MOFs wrapped with Cu(OH)₂ nanowires, building the core-shell structure as the 3D electrode. A novel electrochemical immunosensor for PSA detection has been exploited, using the Cu-MOFs nanowire arrays on Cu foam as a redox signal probe for the first time.

Claros System: A Rapid Microfluidics-Based Point-of-Care System for Quantitative Prostate Specific Antigen Analysis from Finger-Stick Blood

INTRODUCTION

Determination of circulating prostate specific antigen (PSA) is commonly used in the diagnosis and treatment monitoring of prostate cancer [1]. Presently, PSA testing is performed in centralized laboratories, which is associated with prolonged time between venipuncture and the PSA value being available. In this prospective study, we present a new and rapid test system for the quantitative determination of PSA levels from finger-stick blood.

METHODS

The Claros1^® analyzer is a rapid microfluidics-based point-of-care system for quantitative PSA analysis from 10-µl finger-stick blood that requires only 10 min for testing. Total PSA concentrations by the Claros system in 100 consecutive asymptomatic men (median age 57 years, range 44-81 years) were compared with two commercially available, commonly used PSA assays (Abbott and Elecsys by Roche) performed by a reference laboratory.

RESULTS

Eighty-six percent of finger-stick blood-borne probes from 100 men were evaluable for PSA testing by the Claros1^® analyzer system. In 13/14 cases the expiry date of the microfluid cassettes of the Claros system was exceeded and one blood puncture was performed inadequately. The correlations between the Claros results and OPKO-Abbott and OPKO-Roche assay results were high, with R² values of 0.982 and 0.985, respectively. The R² value for the Roche-Abbott correlation was 0.991 with a slope value of 1.160. Prostate cancer was diagnosed in seven cases, with a median PSA of 1.8 ng/ml in the Claros group compared to 1.75 ng/ml and 2.1 ng/ml in the Abbott and Roche groups, respectively.

CONCLUSION

The Claros1^® PSA assay combines the advantages of rapid, accurate detection with a low required sample volume, allowing the analysis to be performed using finger-stick blood. Provided that further analysis proves the reproducibility of the test, it may help to reduce the number of office visits, thus decreasing costs to the health care system.

Vertical flow assays based on core–shell SERS nanotags for multiplex prostate cancer biomarker detection

A core–shell SERS nanotag based VFA with a single test spot for multiplex biomarker detection at pg mL⁻¹ level with a wide LDR.

Use of data processing for rapid detection of the prostate-specific antigen biomarker using immunomagnetic sandwich-type sensors

Diagnosis of cancer using electroanalytical methods can be achieved at low cost and in rapid assays, but this may require the combination with data treatment for determining biomarkers in real samples. In this paper, we report an immunomagnetic nanoparticle-based microfluidic sensor (INμ-SPCE) for the amperometric detection of the prostate-specific antigen (PSA) biomarker, the data of which were treated with information visualization methods. The INμ-SPCE consists of eight working electrodes, reference and counter electrodes. On the working electrodes, magnetic nanoparticles with secondary antibodies with the enzyme horseradish peroxidase were immobilized for the indirect detection of PSA in a sandwich-type procedure. Under optimal conditions, the immunosensor could operate within a wide range from 12.5 to 1111 fg·L^-1, with a low detection limit of 0.062 fg·L^-1. Multidimensional projections combined with feature selection allowed for the distinction of cell lysates with different levels of PSA, in agreement with results from the traditional enzyme-linked immunosorbent assay. The approaches for immunoassays and data processing are generic, and therefore the strategies described here may provide a simple platform for clinical diagnosis of cancers and other types of diseases.

A critical insight into the development pipeline of microfluidic immunoassay devices for the sensitive quantitation of protein biomarkers at the point of care

The latest clinical procedures for the timely and cost-effective diagnosis of chronic and acute clinical conditions, such as cardiovascular diseases, cancer, chronic respiratory diseases, diabetes or sepsis (i.e. the biggest causes of death worldwide), involve the quantitation of specific protein biomarkers released into the blood stream or other physiological fluids (e.g. urine or saliva). The clinical thresholds are usually in the femtomolar to picolomar range, and consequently the measurement of these protein biomarkers heavily relies on highly sophisticated, bulky and automated equipment in centralised pathology laboratories. The first microfluidic devices capable of measuring protein biomarkers in miniaturised immunoassays were presented nearly two decades ago and promised to revolutionise point-of-care (POC) testing by offering unmatched sensitivity and automation in a compact POC format; however, the development and adoption of microfluidic protein biomarker tests has fallen behind expectations. This review presents a detailed critical overview into the pipeline of microfluidic devices developed in the period 2005-2016 capable of measuring protein biomarkers from the pM to fM range in formats compatible with POC testing, with a particular focus on the use of affordable microfluidic materials and compact low-cost signal interrogation. The integration of these two important features (essential unique selling points for the successful microfluidic diagnostic products) has been missed in previous review articles and explain the poor adoption of microfluidic technologies in this field. Most current miniaturised devices compromise either on the affordability, compactness and/or performance of the test, making current tests unsuitable for the POC measurement of protein biomarkers. Seven core technical areas, including (i) the selected strategy for antibody immobilisation, (ii) the surface area and surface-area-to-volume ratio, (iii) surface passivation, (iv) the biological matrix interference, (v) fluid control, (vi) the signal detection modes and (vii) the affordability of the manufacturing process and detection system, were identified as the key to the effective development of a sensitive and affordable microfluidic protein biomarker POC test.

"The Smartphone's Guide to the Galaxy": In Situ Analysis in Space

A human mission to Mars can be viewed as the apex of human technological achievement. However, to make this dream a reality several obstacles need to be overcome. One is devising practical ways to safeguard the crew health during the mission through the development of easy operable and compact sensors. Lately, several smartphone-based sensing devices (SBDs) with the purpose to enable the immediate sensitive detection of chemicals, proteins or pathogens in remote settings have emerged. In this critical review, the potential to piggyback these systems for in situ analysis in space has been investigated on application of a systematic keyword search whereby the most relevant articles were examined comprehensively and existing SBDs were divided into 4 relevant groups for the monitoring of crew health during space missions. Recently developed recognition elements (REs), which could offer the enhanced ability to tolerate those harsh conditions in space, have been reviewed with recommendations offered. In addition, the potential use of cell free synthetic biology to obtain long-term shelf-stable reagents was reviewed. Finally, a synopsis of the possibilities of combining novel SBD, RE and nanomaterials to create a compact sensor-platform ensuring adequate crew health monitoring has been provided.

Detection of anti-p53 autoantibodies in saliva using microfluidic chips for the rapid screening of oral cancer

Autoantibodies have high specificity and stability and are easy to detect. Anti-p53 autoantibodies can be used as biomarkers for the early detection of oral cancer. However, most studies detected anti-p53 in sera samples. In this study, a microfluidic chip combined with magnetic immunoassay, which can automatically detect the concentration of anti-p53 in saliva, was developed. The use of a micromixer can shorten the immunoassay time: the mixing time of the antigen and antibody can be reduced from the original 60 min off-chip to 20 min, making the total immunoassay time around 60 min. A method of moving magnetic beads and the antibody instead of manipulating fluid was utilized to simplify fluid control and decrease contamination caused by non-specific protein adsorption to the surface of reaction wells. The detection limit of anti-p53 was 4 ng mL⁻¹. In addition, a relative concentration of anti-p53 in the saliva of patients was detected in the chip.

A microfluidic chip with multiple reaction wells is capable of automatically detecting anti-p53 autoantibody in saliva for oral cancer screening.

Smartphone based non-invasive salivary glucose biosensor

The present work deals with the development of a non-invasive optical glucose biosensor using saliva samples and a smartphone. The sensor was fabricated with a simple methodology by immobilization of Glucose oxidase enzyme along with a pH responsive dye on a filter paper based strip. The strip changes color upon reaction with glucose present in saliva and the color changes were detected using a smartphone camera through RGB profiling. This standalone biosensor showed good sensitivity and low interference while operating within 20 s response time. We used various means for improvements such as the use of slope method instead of differential response; use of a responsive pH indicator and made numerous tweaks in the smartphone app. Calibration with spiked saliva samples with slopes for (R + G + B) pixels revealed an exponentially increasing calibration curve with a linear detection range of 50-540 mg/dL, sensitivity of 0.0012 pixels sec^-1/mg dL^-1 and LOD of 24.6 mg/dL. The biosensor was clinically validated on both healthy and diabetic subjects divided into several categories based on sex, age, diabetic status etc. and correlation between blood and salivary glucose has been established for better standardization of the sensor. Correlation of 0.44 was obtained between blood and salivary glucose in healthy individuals whereas it was 0.64 and 0.94 in case of prediabetic and diabetic patients respectively. The developed biosensor has the potential to be used for mass diagnosis of diabetes especially in such areas where people remain prohibited from routine analysis due to high healthcare cost. Apart from that, a smartphone would be the only device the user needs for this measurement, along with a disposable low cost test strip.

A novel SERS-based magnetic aptasensor for prostate specific antigen assay with high sensitivity

The accurate and highly sensitive detection of prostate specific antigen (PSA) is particularly important, especially for obese men and patients. In this report, we present a novel aptamer-based surface-enhanced Raman scattering (SERS) sensor that employs magnetic nanoparticles (MNPs) core-Au nanoparticles (AuNPs) satellite assemblies to detect PSA. The high specific biorecognition between aptamer and PSA caused the dissolution of the core-satellite assemblies, thus the concentration of functionalized AuNPs (signal probes) existing in the supernatant was on the rise with the continual addition of PSA. The aptamer-modified MNPs were used as supporting materials and separation tools in the present sensor. With the assistance of magnet, the mixture was removed from the supernatant for the concentration effects. It was found that the corresponding SERS signals from the supernatant were in direct correlation to PSA concentrations over a wide range and the limit of detection (LOD) was as low as 5.0pg/mL. Excellent recovery was also obtained to assess the feasibility of this method for human serum samples detection. All of these results show a promising application of this method. And this novel sensor can be used for the accurate and highly sensitive detection of PSA in clinic samples in the future.

Droplet-based magnetic bead immunoassay using microchannel-connected multiwell plates (μCHAMPs) for the detection of amyloid beta oligomers

Multiwell plates are regularly used in analytical research and clinical diagnosis but often require laborious washing steps and large sample or reagent volumes (typically, 100 μL per well). To overcome such drawbacks in the conventional multiwell plate, we present a novel microchannel-connected multiwell plate (μCHAMP) that can be used for automated disease biomarker detection in a small sample volume by performing droplet-based magnetic bead immunoassay inside the plate. In this μCHAMP-based immunoassay platform, small volumes (30-50 μL) of aqueous-phase working droplets are stably confined within each well by the simple microchannel structure (200-300 μm in height and 0.5-1 mm in width), and magnetic beads are exclusively transported into an adjacent droplet through the oil-filled microchannels assisted by a magnet array aligned beneath and controlled by a XY-motorized stage. Using this μCHAMP-based platform, we were able to perform parallel detection of synthetic amyloid beta (Aβ) oligomers as a model analyte for the early diagnosis of Alzheimer's disease (AD). This platform easily simplified the laborious and consumptive immunoassay procedure by achieving automated parallel immunoassay (32 assays per operation in 3-well connected 96-well plate) within 1 hour and at low sample consumption (less than 10 μL per assay) with no cumbersome manual washing step. Moreover, it could detect synthetic Aβ oligomers even below 10 pg mL(-1) concentration with a calculated detection limit of ∼3 pg mL(-1). Therefore, the μCHAMP and droplet-based magnetic bead immunoassay, with the combination of XY-motorized magnet array, would be a useful platform in the diagnosis of human disease, including AD, which requires low consumption of the patient's body fluid sample and automation of the entire immunoassay procedure for high processing capacity.

Biomarker detection technologies and future directions

Biomarkers play a vital role in disease detection and treatment follow-up. It is important to note that diseases in the early stage are typically treated with the greatest probability of success. However, due to various technical difficulties in current technologies for the detection of biomarkers, the potential of biomarkers is not explored completely. Therefore, the developments of technologies, which can enable the accurate detection of prostate cancer at an early stage with simple, experimental protocols are highly inevitable. This critical review evaluates the current methods and technologies used in the detection of biomarkers. The aim of this article is to provide a comprehensive review covering the advantages and disadvantages of the biomarker detection methods. Future directions for the development of technologies to achieve highly selective and sensitive detection of biomarkers for point-of-care applications are also commented on.

Biomarker detection for disease diagnosis using cost-effective microfluidic platforms

Early and timely detection of disease biomarkers can prevent the spread of infectious diseases, and drastically decrease the death rate of people suffering from different diseases such as cancer and infectious diseases. Because conventional diagnostic methods have limited application in low-resource settings due to the use of bulky and expensive instrumentation, simple and low-cost point-of-care diagnostic devices for timely and early biomarker diagnosis is the need of the hour, especially in rural areas and developing nations. The microfluidics technology possesses remarkable features for simple, low-cost, and rapid disease diagnosis. There have been significant advances in the development of microfluidic platforms for biomarker detection of diseases. This article reviews recent advances in biomarker detection using cost-effective microfluidic devices for disease diagnosis, with the emphasis on infectious disease and cancer diagnosis in low-resource settings. This review first introduces different microfluidic platforms (e.g. polymer and paper-based microfluidics) used for disease diagnosis, with a brief description of their common fabrication techniques. Then, it highlights various detection strategies for disease biomarker detection using microfluidic platforms, including colorimetric, fluorescence, chemiluminescence, electrochemiluminescence (ECL), and electrochemical detection. Finally, it discusses the current limitations of microfluidic devices for disease biomarker detection and future prospects.

3D sandwich-type prostate specific antigen (PSA) immunosensor based on rGO–MWCNT–Pd nanocomposite

A signal amplifying sandwich-type immunosensor with a wide linear range and a low detection limit is developed with potential clinical and diagnostic applications.

A fluorescence active gold nanorod–quantum dot core–satellite nanostructure for sub-attomolar tumor marker biosensing

The accurate monitoring of trace cancer biomarkers is crucial for the early diagnosis of cancer.

Clinical laboratory data: acquire, analyze, communicate, liberate

The availability of portable healthcare devices, which can acquire and transmit medical data to remote experts would dramatically affect healthcare in areas with poor infrastructure. Smartphones, which feature touchscreen computer capabilities and sophisticated cameras, have become widely available with over billion units shipped in 2013. In the clinical laboratory, smartphones have recently brought the capabilities of key instruments such as spectrophotometers, fluorescence analyzers and microscopes into the palm of the hand. Several research groups have developed sensitive and low-cost smartphone-based diagnostic assay prototypes for testing cholesterol, albumin, vitamin D, tumor markers, and the detection of infectious agents. This review covers the use of smartphones to acquire, analyze, communicate, and liberate clinical laboratory data. Smartphones promise to dramatically improve the quality and quantity of healthcare offered in resource-limited areas.

A lab-in-a-briefcase for rapid prostate specific antigen (PSA) screening from whole blood

We present a new concept for rapid and fully portable prostate specific antigen (PSA) measurements, termed "lab-in-a-briefcase", which integrates an affordable microfluidic ELISA platform utilising a melt-extruded fluoropolymer microcapillary film (MCF) containing an array of 10 200 μm internal diameter capillaries, a disposable multi-syringe aspirator (MSA), a sample tray pre-loaded with all of the required immunoassay reagents, and a portable film scanner for colorimetric signal digital quantification. Each MSA can perform 10 replicate microfluidic immunoassays on 8 samples, allowing 80 measurements to be made in less than 15 minutes based on semi-automated operation, without the need of additional fluid handling equipment. The assay was optimised for the measurement of a clinically relevant range of PSA of 0.9 to 60.0 ng ml(-1) in 15 minutes with CVs on the order of 5% based on intra-assay variability when read using a consumer flatbed film scanner. The PSA assay performance in the MSA remained robust in undiluted or 1 : 2 diluted human serum or whole blood, and the matrix effect could simply be overcome by extending sample incubation times. The PSA "lab-in-a-briefcase" is particularly suited to a low-resource health setting, where diagnostic labs and automated immunoassay systems are not accessible, by allowing PSA measurement outside the laboratory using affordable equipment.

Surface modification of PDMS microchips with poly(ethylene glycol) derivatives for μTAS applications

In this work is presented a method for the modification of native PDMS surface in order to improve its applicability as a substrate for microfluidic devices, especially in the analysis of nonpolar analytes. Therefore, poly(ethylene glycol) divinyl ether modified PDMS substrate was obtained by surface modification of native PDMS. The modified substrate was characterized by attenuated total reflectance infrared spectroscopy, water contact angle measurements, and by evaluating the adsorption of rhodamine B and the magnitude of the EOF mobility. The reaction was confirmed by the spectroscopic evaluation. The formation of a well-spread water film over the surface immediately after the modification was an indicative of the modified surface hydrophilicity. This characteristic was maintained for approximately ten days, with a gradual return to a hydrophobic state. Fluorescence assays showed that the nonpolar adsorption property of PDMS was significantly decreased. The EOF mobility obtained was 3.6 × 10(-4) cm(2) V(-1) s(-1) , higher than the typical values found for native PDMS. Due to the better wettability promoted by the modification, the filling of the microchannels with aqueous solutions was facilitated and trapping of air bubbles was not observed.