Prostate-specific Antigen Antibody Research Articles

Ultrasensitive detection of prostate-specific antigen using a SERS-based magnetic immunosensor

Concentrations of disease biomarkers and their changes are crucial for the diagnosis and monitoring of diseases, so detecting and capturing small changes in biomarkers is especially important. This study demonstrates a surface-enhanced Raman scattering (SERS)-active magnetic immunosensor using a signal amplification strategy for the ultrasensitive detection of prostate-specific antigen (PSA). The sensor consists of a biotin-modified aptamer (B-Apt) and a PSA antibody (Ab) labeled on magnetic beads (MBs), which can immobilize and anchor the target PSA when it is present. After sequential addition of streptavidin and a signal probe, the generated streptavidin-biotin complex reacts to form a three-dimensional network, thereby increasing the number of signal molecules to achieve signal amplification, with the detection limit of 0.87 pg/mL. In addition, this method was also performed to detect PSA in human serum samples. It is believed that this method provides a more sensitive tool for detecting PSA or other biomarkers in clinical samples.

Ag NC and Ag NP/PorC Film-Based Surface-Enhanced Raman Spectroscopy-Type Immunoassay for Ultrasensitive Prostate-Specific Antigen Detection.

Surface-enhanced Raman scattering (SERS) is a spectral detection technology with high sensitivity and detectivity and can be used to detect the fingerprint information of the molecules with ultralow concentration. Herein, a kind of immunostructure constructed by Ag nanoparticle/porous carbon (Ag NP/PorC) films as the immunosubstrate and Ag NCs as the immunoprobes was presented for ultralow level prostate-specific antigen (PSA) detection. Experimentally, the Ag NP/PorC film was first prepared with a facile method by carbonizing the gelatin-AgNO3 film in air, and Ag NCs were synthesized by the hydrothermal method. Then, the Ag NP/PorC film was modified by PSA antibodies as the substrate, while Ag NCs were decorated by R6G and PSA antibodies for probes. The sandwiched SERS detection embodiment was constructed by the immunoreaction between the PSA and PSA antibody predecorated on the substrate and probes. Our results show that the proposed SERS-type immunoassay is highly sensitive and selective to a wide range of PSA concentrations from 10-5 to 10-12 g/mL. Thereafter, it was also implemented to detect the PSA level in human serum, and the results successfully reproduce the PSA levels as those measured by the chemiluminescence method with a recovery rate above 90%. All in all, this SERS-type immunoassay provides a promising method for the early diagnosis of prostate cancer.

Bioorthogonal chemistry-based high-efficient quantum dots binding boosts the detection sensitivity of plasmon-enhanced fluorescence platform for immunoassay

Although plasmon-enhanced fluorescence (PEF) technology has been demonstrated its potential in protein detection for disease early diagnosis, its detection sensitivity still has a big gap compared to that of methods featured with single-molecule detection ability. Herein, inspired by the properties of catalyst-free bioorthogonal chemistry between 1,2,4,5-tetrazine (Tz) and trans-cyclooctene (TCO) being capable of improving the nanoparticle binding efficiency, we initially incorporate semiconductor quantum dots (QDs) into PEF-based suspension microarray platform as the signal reporter and evaluate its performance for biomarker prostate-specific antigen (PSA) detection by comparing with traditional fluorescence protein-based methods. In our assay, Tz-tagged QDs could be readily absorbed onto the sandwich immunocomplex composed of capture antibody, target PSA and TCO-labelled detection antibody for signal output. To improve the QDs binding efficiency, detection performance obtained from QDs-conjugated detection antibody as the reporter prepared by the same bioorthogonal chemistry reaction was also evaluated. For the evaluation of its potential in practical application, the performance including detection sensitivity and dynamic range of the proposed method for PSA assay in clinical sera samples using commercially-available PEF-based planar microarray as the control was discussed, which revealed that the nanoparticle-binding efficiency base on traditional SA/avidin method could be dramatically improved by the proposed method.

A sensitive label-free biosensor based on Ag2S-sensitived Bi2WO6/BiOBr heterojunction for photoelectrochemical immunoassay of prostate specific antigen

Prostate cancer is one of the most common cancers in the world, and its early diagnosis can effectively reduce mortality. A new label-free photoelectrochemical (PEC) immunosensor on the basis of Bi2WO6/BiOBr nanocomposite materials has been successfully prepared for the test of prostate-specific antigen (PSA) in human serum in this work. The Ag2S-sensitized Bi2WO6/BiOBr heterojunction was used as a photosensitive material, which effectively improved the photocurrent response. On Bi2WO6/BiOBr surface, dopamine immobilized PSA antibody by self-polymerizing to form polydopamine membrane. Antigen and antibody are specifically combined to achieve quantitative detection of PSA according to the current changes at different concentrations of antigen. Under the optimal experimental conditions, the PEC immunosensor has an ideal linear relationship between 1 pg/mL - 50 ng/mL, and the detection limit is 0.084 pg/mL. In addition, the prepared immunosensor has good stability, reproducibility and selectivity, providing a new method for the detection of PSA in actual sample analysis.

Capacitive label-free ultrasensitive detection of PSA on a covalently attached monoclonal anti-PSA antibody gold surface

• The design of an ultrasensitive label-free detection of prostate specific antigen (PSA) was achieved. • The fabricated immunosensor used monoclonal anti-PSA antibody as capture probe on an electrografted isophthalic thin fim. • Capacitance signals were deconvoluted from the impedance plots and were sensitive to PSA concentrations. • The detection of PSA could be achieved in fg.ml -1 . A rapid, low-cost, and accurate point-of-care analytical device for the determination of prostate-specific antigen (PSA) is required for the early diagnosis and prognosis of prostate cancer (PCa). In this work, an electrochemical capacitive immunosensor was developed for the label-free detection of PSA. The immunosensor was based on the covalent immobilization of monoclonal anti -PSA antibody via carbodiimide chemistry onto gold electrode pre-modified with a thin monolayer film of isophthalic acid (IPA). A methodology based on the steric hindrance of 1,3-substituted aryldiazonium salt was adopted to control the growth of the IPA thin film on the gold electrode. The non-specific binding sites were blocked with bovine serum albumin (BSA) to afford an AuE-IPA- anti -PSA-mAb|BSA immunosensor. The immunosensor was characterized by X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The analytical performance of the developed sensor was evaluated using the capacitance Nyquist plots generated from the complex impedance data. In addition, complex capacitance was also calculated from the imaginary part of the impedance and plotted against the log of frequency. The double layer capacitance from the circuit fitting (R S C) was also used and compared the sensitive capacitance signals to the changes in PSA concentrations. The LOD values were in fg.mL -1 and distinguishable from the blank (PBS) for the Nyquist plots of capacitance, complex capacitance, and double layer capacitance signals. The developed immunosensor exhibited good stability, selectivity, low detection limits, and a wide linear range which was suitable for screening of prostate cancer using prostate-specific antigen.

Antifouling zwitterionic peptide hydrogel based electrochemical biosensor for reliable detection of prostate specific antigen in human serum

An electrochemical biosensor based on the antifouling zwitterionic peptide hydrogel (CFEFKFC) and the poly(3,4-ethylenedioxythiophene) (PEDOT) was fabricated to accurately detect prostate specific antigen (PSA) in complex human serum. The electrode was modified with the conducting polymer PEDOT and gold nanoparticles (AuNPs) in sequence through electrodeposition, and then the designed zwitterionic peptide hydrogel prepared through self-assembly was immobilized onto the modified electrode surface via the Au–S bond. The zwitterionic peptide hydrogel with cysteine terminal is easy for immobilization onto the gold surface, and it is also suitable for the immobilization of biomolecules such as PSA antibody in this work, through the formation of covalent amide bonds. The peptide hydrogel possessed excellent antifouling property, and it was able to effectively prevent the adsorption of nonspecific proteins, cells and other biomolecules. The developed antifouling biosensor showed a linear response range from 0.1 ng mL−1 to 100 ng mL−1, with a low limit of detection down to 5.6 pg mL−1. These results encourage the wide use of zwitterionic peptide hydrogels as antifouling materials in various sensing and bio-sensing devices.

A Novel, Quick, and Reliable Smartphone-Based Method for Serum PSA Quantification: Original Design of a Portable Microfluidic Immunosensor-Based System.

Simple SummaryProstate cancer (PCa) is the most frequently diagnosed malignancy and second most common cause of cancer-related death in males. An early diagnosis is crucial to improve the prognosis. Prostate-Specific Antigen (PSA) is the most widely used biomarker for PCa, but this type of biomarker analysis is performed in centralized laboratories, delaying the diagnosis and initiation of treatment. Our team has developed a miniaturized platform for portable PSA quantification to overcome this shortcoming. It includes a microfluidic chip, immune capture of PSA by magnetic microbeads, and electrochemical quantification. The utilization of a micro-potentiostat allows PSA levels to be read on a smartphone in less than 30 min. This technique was found to offer a fast, easy, specific, sensitive, and reproducible method for PSA quantification. Further research is warranted to verify these findings and explore its potential application at all health care levels.We describe a versatile, portable, and simple platform that includes a microfluidic electrochemical immunosensor for prostate-specific antigen (PSA) detection. It is based on the covalent immobilization of the anti-PSA monoclonal antibody on magnetic microbeads retained in the central channel of a microfluidic device. Image flow cytometry and scanning electron microscopy were used to characterize the magnetic microbeads. A direct sandwich immunoassay (with horseradish peroxidase-conjugated PSA antibody) served to quantify the cancer biomarker in serum samples. The enzymatic product was detected at −100 mV by amperometry on sputtered thin-film electrodes. Electrochemical reaction produced a current proportional to the PSA level, with a linear range from 10 pg mL−1 to 1500 pg mL−1. The sensitivity was demonstrated by a detection limit of 2 pg mL−1 and the reproducibility by a coefficient of variation of 6.16%. The clinical performance of this platform was tested in serum samples from patients with prostate cancer (PCa), observing high specificity and full correlation with gold standard determinations. In conclusion, this analytical platform is a promising tool for measuring PSA levels in patients with PCa, offering a high sensitivity and reduced variability. The small platform size and low cost of this quantitative methodology support its suitability for the fast and sensitive analysis of PSA and other circulating biomarkers in patients. Further research is warranted to verify these findings and explore its potential application at all healthcare levels.

A Sensitive Fluorescent Immunoassay for Prostate Specific Antigen Detection Based on Signal Amplify Strategy of Horseradish Peroxidase and Silicon Dioxide Nanospheres

A simple, sensitive, and fluorescent immunoassay for the detection of prostate-specific antigen (PSA) based on horseradish peroxidase and silicon dioxide nanospheres as a signal amplification strategy has been described. In the design, the primary antibody (Ab1) of PSA was first immobilized on the 96-well plates via physical adsorption between polystyrene and hydrophobic groups of the antibody molecule. The silicon dioxide nanospheres (SiO2 NSs), with large surface area and good biocompatibility, were loaded with horseradish peroxidase (HRP) and horseradish peroxidase-labeled secondary antibodies (HRP-Ab2) as signal amplification systems. In the presence of PSA, a sandwich-type immunocomplex composed of Ab1-Ag-HRP-Ab2 had been formed. Fluorescence technology was employed to obtain the response signal of the immunoassay in the L-tyrosine and H2O2 systems. Experiment results showed that a strong and stable fluorescent signal at 416 nm (excitation wavelength: 325 nm) was observed, and the changes in fluorescent intensity were related to the levels of PSA. Under the optimal conditions, the relative fluorescence intensity was linear with the logarithm of PSA concentration from 0.03 to 100 ng·mL−1, with a detection limit of 0.01 ng·mL−1 (at a signal/noise ratio of 3). In contrast to other fluorescent immunoassays, the sandwich-type immunoreaction based on the high binding ELISA plates has the advantages of being simple, stable, and easy to operate, high selectivity, small sample quantity, etc., which can be widely used in the selective detection of a variety of targets, from DNA to proteins and small molecules. Such fluorescent immunoassays should be feasible for the fields of molecular diagnosis and other life science fields in the future.

Ultrasensitive Immunosensor for Prostate-Specific Antigen Based on Enhanced Electrochemiluminescence by Vertically Ordered Mesoporous Silica-Nanochannel Film.

Ultrasensitive and specific detection of prostate-specific antigen (PSA) in complex biological samples is crucial for early diagnosis and treatment of prostate-related diseases. Immunoassay with a simple sensing interface and ultrahigh sensitivity is highly desirable. Herein, a novel electroluminescence (ECL) immunosensing platform is demonstrated based on the equipment of vertically ordered mesoporous silica-nanochannel films (VMSFs) with PSA antibody, which is able to realize ultrasensitive detection of PSA in human serum. Through the electrochemically assisted self-assembly (EASA) method, the VMSF is easily grown on an indium tin oxide (ITO) electrode in a few seconds. Owing to a large surface area and the negatively charged surface, VMSF nanochannels display strong electrostatic attraction to the positively charged ECL luminophores (tris(2,2-bipyridyl) dichlororuthenium (II), (Ru(bpy)3 2+), leading to two orders-of-magnitude enhancement of ECL emission compared with that of the bare ITO electrode. The outer surface of the VMSF is functionalized with reactive epoxy groups, which further allows covalent attachment of PSA antibody (Ab) on the entry of nanochannels. As the combination of PSA with Ab decreases the ECL signal by hindering the mass transfer of ECL luminophores and coreactant, the developed immunosensor can achieve ultrasensitive detection of PSA ranging from 1 pg ml−1 to 100 ng ml−1 with a limit of detection (LOD) of 0.1 pg ml−1. Considering the antifouling ability of the VMSF, sensitive detection of PSA in human serum is also realized. The proposed nanochannel-based immunosensor may open up a new way for the facile development of the universal immunosensing platform for rapid and ultrasensitive detection of disease markers.

Ultrasensitive WSe2 field-effect transistor-based biosensor for label-free detection of cancer in point-of-care applications

We demonstrate a highly sensitive tungsten diselenide (WSe2) field-effect transistor (FET) biosensor for label-free detection of early stage prostate cancer. We modified the FET channel by attaching the monoclonal antibody of prostate specific antigen (anti-PSA) through a multi-step process, followed by bovine serum albumin treatment, which ensures specific binding between anti-PSA and PSA. Our FET biosensor has a detection limit of 10 PSA, the lowest concentration detected so far by any FET sensor. At this detection limit, the sub-threshold swing is ; and the drain current () in the FET increases by 70% compared to that in a pristine device. The FET sensor exhibits linear change in threshold voltage () and drain current () over the detection range of 10 –1 PSA. Our demonstrated ultra-sensitive and fast WSe2 FET biosensors are promising for point-of-care diagnostics applications.

A novel and highly sensitive sandwich-type immunosensor for prostate-specific antigen detection based on MWCNTs-Fe3O4 nanocomposite

Due to the importance of early diagnosis of prostate cancer, an ultrasensitive electrochemical immunosensor was developed to detect prostate-specific antigen (PSA) biomarker. The biosensor was designed based on modification of the glassy carbon electrode (GCE) surface with a nanocomposite of carboxyl functionalized multi-walled carbon nanotubes (MWCNTs), and Fe3O4 nanoparticles with unique properties for signal amplification that was synthesized using a new method. MWCNTs with COOH groups were a good substrate to modify the electrode for the binding of anti-total PSA antibody (Ab1) to form a sandwich-like structure. Also, Fe3O4 nanoparticles with their magnetic properties played a key role in signal amplification and facilitating electron transfer. Horseradish peroxidase (HRP)-labeled anti-free PSA antibody (Ab2) led to the reduction of hydrogen peroxide (H2O2) in the electrochemical cell and increased the current by adding a higher concentration of PSA that is the basis of the biosensor analysis performance. The immunosensor showed a limit of detection (LOD) of 0.39 pg/mL to measure PSA with a wide linear range from 2.5 pg/mL to 100 ng/mL. This immunosensor has high reproducibility and stability and indicated suitable performance for measuring PSA both in real serum samples and in laboratory solution. This raises hopes for the use of this type of sensor in diagnostic clinics in the future.

A novel affinity peptide–antibody sandwich electrochemical biosensor for PSA based on the signal amplification of MnO2-functionalized covalent organic framework

This work describes a novel affinity peptide–antibody sandwich electrochemical strategy for the ultrasensitive detection of prostate-specific antigen (PSA). Herein, polydopamine-coated boron-doped carbon nitride (Au@PDA@BCN) was synthesized and used as a sensing platform to anchor gold nanoparticles and immobilize primary antibody. Meanwhile, AuPt metallic nanoparticle and manganese dioxide (MnO2)-functionalized covalent organic frameworks (AuPt@MnO2@COF) was facilely synthesized to serve as a nanocatalyst and ordered nanopore for the enrichment and amplification of signal molecules (methylene blue, MB). PSA affinity peptide was bound to AuPt@MnO2@COF to form Pep/MB/AuPt@MnO2@COF nanocomposites (probe). The peptide–PSA–antibody sandwich biosensor was constructed, and the redox signal of MB was measured with the existence of PSA. The fabricated sensor exhibited a linear response (0.00005–10 ng mL−1) with a low detection limit of 16.7 fg mL−1 under the optimum condition. Additionally, the sensor showed an excellent selectivity, ideal repeatability, and good stability for PSA detection in real samples. Furthermore, the porous structure of COF can enrich more MB molecules and increase the sensitivity of the biosensor. This study provides an efficient and ultrasensitive strategy for PSA detection and broadens the use of organic/inorganic porous nanocomposite in biosensing.

Oxygen plasma-enhanced covalent biomolecule immobilization on SU-8 thin films: A stable and homogenous surface biofunctionalization strategy

SU-8 is an attractive platform for the development of smart biochips owing to its high aspect ratio of micro/nanostructures fabrication and remarkable optical and biocompatible properties. However, few works have explored sub-micron SU-8 thin films for applications in new generations of portable bioanalytical devices. In this work we discuss surface properties for the efficient immobilization of different bioanalytical components on SU-8 thin film surfaces. Short exposure time oxygen plasma treatment improved hydrophilicity and activation of surface carboxyl groups of 300 nm-thick SU-8 films, while maintaining surface roughness below 2 nm. Under these optimized surfaces conditions, covalent immobilization of Interleukin-6 and Prostate Specific Antigen antibodies on SU-8 surfaces was evaluated using quantitative fluorescence microscopy. The addition of standard crosslinker, 1-ethyl-3-(3-(dimethylamino)-propyl)-carbodiimide and N-hydroxysuccinimide mixture to our protocol yielded 15–20% higher antibody immobilization due to activation of surface carboxyl groups. The stability of the plasma treatment along time, and the ideal surface passivation of functionalized samples are demonstrated, along with the selective immobilization antibody to photolithographically-patterned SU-8 microstructures. Overall, our optimized protocol could find broad applications of functionalized SU-8 thin films in biomedical fields, particularly for the fabrication of SU-8 based miniaturized photonic and plasmonic biosensors.

LSPR biosensing for the early-stage prostate cancer detection using hydrogen bonds between PSA and antibody: Molecular dynamic and experimental study

Prostate specific antigen (PSA) as a prostate cancer marker has a significant role in screening the tumor in the initial stages. The LSPR is a versatile and robust technique among the PSA detection methods. In this study an ultra-sensitive label-free nanobiosensor was designed for determination of PSA at low concentration level in serum samples using antibody conjugated‑gold nanoparticle (GNP) and the high affinity binding mechanism of antibody/GNP probe with PSA protein was investigated by computational modeling. The first crystal structure of the complex between human PSA and monoclonal antibody (mAb) 8G8F5 were studied using molecular dynamics (MD) simulations. MD simulation also supports the formation of the antibody–PSA complex. The sensing principle is based on the LSPR peak shift produced by small changes in the refractive index of the dielectric medium around the probe upon binding to the antigen. The GNPs were synthesized by the citric acid reduction method and characterized by the UV–Vis spectrophotometry and dynamic light scattering. The 10 nm gold nanoparticles were covalently conjugated to the anti-PSA antibody and the affecting factors such as the concentration ratio of the antibody to Au NPs, pH and temperature were optimized. A detection limit of 0.2 ng mL−1, and calibration sensitivity of 43.75 nm/(ng mL−1) were obtained.

Highly Sensitive Immunofluorescence Assay of Prostate-Specific Antigen Using Silver Nanoparticles

We consider the possibilities of applying the plasmon-enhanced fluorescence of monoclonal antibodies labelled with fluorescein isothiocyanate (FITC) to the prostate-specific antigen (PSA) for increasing the immunofluorescence analysis sensitivity. An immunochemical test system featuring two center binding using a pair of noncompeting monoclonal antibodies in combination with silver plasmon nanoparticles was used for the first time for determining the PSA concentration. The advantages over the standard PSA immunofluorescence assay are as follows. The intensity of the recorded fluorescent signal is enhanced by 2.3–3.2 times in the presence of silver nanoparticles in comparison with the signal of the test system on the intact surface of a polystyrene plate. The signal-to-noise ratio is increased by up to two times. In addition to the plasmon-enhanced fluorescence, the effect of an intermediate polyelectrolyte layer for enhancement of the adsorption capacity of the primary PSA antibodies is shown, which, in turn, affects the fluorescence signal intensity. Growth of the plasmon fluorescence enhancement factor with increasing concentration of the labelled antibodies indicates suppression of the self-quenching of the fluorescent labels by metal nanoparticles.

A novel chemiluminescence imaging immunosensor for prostate specific antigen detection based on a multiple signal amplification strategy

A novel chemiluminescence (CL) imaging platform was constructed for prostate specific antigen (PSA) detection in a multiple signal amplifying manner. To construct the platform, the primary antibody for PSA was firstly immobilized on a O-ring area of a glass slide for recognizing the PSA. The horseradish peroxidase (HRP) and the secondary antibody of PSA (Ab2) functionalized Au NPs (HRP-Au NPs-Ab2) were modified on the platform through immunoreaction between PSA and Ab2. The excellent catalytic effect of Au NPs and HRP on the HRP-Au NPs-Ab2 to the luminol-H2O2 CL system provided the dual-signal amplification for PSA detection. To further enhance the sensitivity, tyramine signal amplification (TSA) strategy was introduced: tyramine-HRP conjugates were added into the O-ring reservoir and thus tyramine-HRP repeats formed in the presence of H2O2, generating a multiple signal amplification because of the large amounts of HRP on the sensing interface. The excellent performance of HRP-Au NPs-Ab2 and TSA strategy endows the CL platform with high sensitivity. The PSA was detected with a photomultiplier tube (PMT) and visually analyzed by a charge coupled device (CCD), respectively. The linear ranges of PMT and CCD for PSA are 0.1–100.0 ng mL-1 with a detection limit of 0.05 pg mL-1 and 0.5 – 100.0 ng mL-1 with a detection limit of 0.1 pg mL-1, respectively. The levels of PSA in several human serum samples were determined and the recoveries are ranged from 82.5% – 117.0%. This CL immunosensing platform holds great potential for bioactive molecules detection visually and sensitively.

Label-free electrochemical immunosensor for the detection of prostate specific antigen based three-dimensional Au nanoparticles/MoS2-graphene aerogels composite

In the present work, a label-free prostate specific antigen (PSA) electrochemical immunosnesor was constructed based on Au nanoparticles/MoS2-graphene aerogels nanocomposite (AuNPs/MoS2-GAs) as sensing platform. MoS2-GAs composite with porous network structure provided large specific area for the immobilization of AuNPs, which further improved the loading of PSA antibodies. In addition, the AuNPs/MoS2-GAs composite has good conductivity, which could accelerate the electron transport of the electrode interface. Based on these advantages of AuNPs/MoS2-GAs material, the prepared immunosensor exhibited wide linearity in the range of 0.00001–50 ng mL−1 and a low detection limit of 0.003 pg mL−1. The immunosensor also exhibited acceptable stability, good selectivity, and reproducibility. Moreover, when applied to analyze PSA in human serum, the immunosensor obtained good recovervries, indicating the method shows a promising application for early diagnosis of PSA.

Photoelectrochemical Immunosensor for Sensitive Quantification of Prostate Specific Antigen in Human Serum Samples Exploiting BaTiO3−CdS

AbstractA novel label‐free photoelectrochemical immunosensor was developed for the determination of prostate‐specific antigen (PSA) based on fluorine‐doped tin oxide (FTO) electrode modified with barium titanate and cadmium sulfide (BaTiO3−CdS/FTO). The photoelectrochemical current density of the BaTiO3 platform sensitized with CdS for the ascorbic acid (AA) donor molecule was higher than that observed in the absence of CdS. The BaTiO3−CdS/FTO platform was modified with PSA antibodies to produce the anti‐PSA/BaTiO3−CdS/FTO immunosensor, which was incubated in solutions of PSA to inhibit the photocurrent density of the immunosensor for AA. The photocurrent density of the anti‐PSA/BaTiO3−CdS/FTO immunosensor presented a linear relationship with the logarithm of the PSA concentration ranging from 1 pg mL−1 to 1 μg mL−1 with good sensitivity. The proposed method presented an experimental detection limit of 1 pg mL−1 (S/N=3). The immunosensor was successfully employed for the determination of PSA in blood serum samples, with recoveries between 98.7 %–104.4 %.

A novel immunosensor for the monitoring of PSA using binding of biotinylated antibody to the prostate specific antigen based on nano-ink modified flexible paper substrate: efficient method for diagnosis of cancer using biosensing technology

Prostate cancer is the most significant reason for deaths in men, outside of lung cancer. The clinical examination of cancer proteins or biomarkers is extremely significant in early examination and monitoring of recurrence of disease after treatment. Biomarkers have expanded great clinical significance owing to their extensive spectra in the identification, elimination, early diagnosis and cure of cancer. In this work, novel, ultrasensitive sandwich-type portable bio device based on citrate-capped silver nanoparticles (Citrate-AgNPs) modified graphene quantum dots (GQDs) nano ink for detection of Prostate specific antigen (PSA) was fabricated. Functionalized cysteamine with gold nanoparticles (Cys-AuNPs) was also utilized to amplify the signal. It provides a good and high external area for the immobilization biotinylated antibody of PSA in the large amount. For the first time, citrate-AgNPs-GQDs nano ink was directly written on the cellulose paper surface (ivory sheet and photographic paper) and modified by Cys-AuNPs. So, final structure of the immunodevices was completed after including of Ab1 and PSA (antigen). The immunosensors were used for the recognition of PSA by using DPVs (differential pulse voltammetry) technique. The obtained low limit of quantification (LLOQ) of the first immunodevice (ivory sheet/Citrate AgNPs-GQDs nano-ink/CysA-Au NPs/Ab1/BSA/PSA/Ab2) was 0.07 μg/L and the linear range for the calibration plot was from 0.07 to 60 μg/L. Also, the achieved LLOQ of the second immunodevice (photographic paper/Citrate AgNPs-GQDs nano-ink/Cys-Au NPs/Ab1/BSA/PSA/Ab2) was 0.05 μg/L with the linear range of 10 to 0.05 μg/L. It is noteworthy that, proposed immunoassay was effectively utilized to the monitoring of PSA glycoprotein in unprocessed human plasma sample. Obtained results show that the constructed immunosensor is able to apply as portable bio device for the clinical analysis of PSA in human plasma samples.

Highly sensitive photoelectrochemical immunosensor based on anatase/rutile TiO2 and Bi2S3 for the zero-biased detection of PSA

A novel label-free photoelectrochemical immunosensor was developed for the determination of prostate-specific antigen (PSA) based on fluorine-doped tin oxide (FTO) electrode modified with anatase and rutile titanium dioxide nanoparticles (TiO2(a-r)) as a platform for the electrodeposition of bismuth sulfide (Bi2S3). The photoelectrochemical response of the TiO2(a-r) platform sensitized with Bi2S3 for the ascorbic acid donor molecule (AA) was about 34-fold higher than that observed in the absence of Bi2S3. The Bi2S3/TiO2(a-r)/FTO platform was modified with PSA antibodies to produce the anti-PSA/Bi2S3/TiO2(a-r)/FTO immunosensor, which was incubated in solutions of PSA antigen to inhibit the photocurrent of the immunosensor for AA. The photocurrent of the anti-PSA/Bi2S3/TiO2(a-r)/FTO immunosensor presented a linear relationship with the logarithm of the PSA concentration ranging from 1 pg mL−1 to 100 ng mL−1 with good sensitivity and a limit of detection of 0.870 pg mL−1. The sensor was successfully employed for the determination of PSA in artificial blood plasma samples, with recoveries between 94.6 and 98.6%.