Prostate-specific Antigen Antibody Research Articles

Fabrication of a sensitive label free electrochemical immunosensor for detection of prostate specific antigen using functionalized multi-walled carbon nanotubes/polyaniline/AuNPs.

The aim of this research is to introduce a novel label free electrochemical immunosensor based on glassy carbon electrode (GCE) modified with carboxylated carbon nanotubes (COOH-MWCNTs)/polyaniline (PANI)/gold nanoparticles (AuNPs) for the detection of prostate specific antigen (PSA). The AuNPs were utilized as a connector for PSA antibody immobilization through NH2 groups on antibody. Investigations on modified electrode surface were performed by FT-IR spectrum, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS) to evaluate the synthesized nanocomposite and modified electrode surface. As a sensitive analytical method for the detection of PSA, differential pulse voltammetry (DPV) was employed in different ranges of antigen concentration, 1.66 ag·mL-1 to 1.3ng·mL-1. In addition, the detection limit was obtained 0.5pg·mL-1, from the linear relationship between antigen concentration log and peak current. Also, the proposed immunosensor was carried out for the determination of PSA in human serum samples, indicating recoveries ranging from 92 to 104%. Finally, it should be noted that the reproducibility and specificity, along with the stability of the present immunosensor were examined, and satisfactory findings were obtained, thus proving it as a promising PSA immunosensor.

Porous graphene based electrochemical immunosensor using Cu3(BTC)2 metal-organic framework as nonenzymatic label

An electrochemical immunosensor for highly sensitive detection of cancer biomarkers has been developed based on the combination of a sensing platform of polydopamine modified porous graphene and a nonenzymatic label of metal-organic framework (MOF) conjugated secondary antibody. This approach achieves a wide range of linear response from 0.1 to 10 ng/mL, low detection limit of 0.025 ng/mL (at a signal to noise ratio of 3), good reproducibility and selectivity for the detection of prostate specific antigen (PSA) as a model analyte. The high performance of the immunosensor is attributed to the high surface area from porous graphene and the strong adhesion of polydopamine, allowing a high load of the primary antibody of PSA, as well as the highly electrocatalytic activity of the Cu3(BTC)2 (BTC = benzene-1,3,5-tricarboxylic acid) MOF toward H2O2 to provide greatly amplified sensitivity. In this respect, the MOF-based nonenzymatic label shows promising application for the point-of-care detection of different cancer biomarkers in clinical diagnostics.

A signal amplification strategy for prostate specific antigen detection via releasing oxidase-mimics from coordination nanoparticles by alkaline phosphatase

A novel signal amplification method for prostate specific antigen (PSA) is developed by freeing fluorescein with photoinduced oxidase-like activity from coordination nanoparticles (CNPs) in the presence of alkaline phosphatase (ALP). CNPs loaded with fluorescein (F@CNPs) are obtained in aqueous solution by self-assembly using Tb3+ as metal ion, guanosine monophosphate (5′-GMP) as ligand, and fluorescein as signal molecule. The F@CNPs display outstanding properties of simple synthesis, low cost, good water solubility, negligible leakage and satisfactory load capacity. Fluorescein is quantitatively encapsulated in CNPs with a binding ratio of 92.72%. Meanwhile, ALP can specifically hydrolyze the phosphate group of 5′-GMP ligand, triggering the destruction of F@CNPs and leakage of fluorescein. Fluorescein, a photoinduced oxidase mimic, can catalyze the oxidation of non-fluorescent Amplex UltraRed (AUR) into fluorescent resorufin under LED lamp. This strategy exhibits good sensitivity for ALP detection. In addition, a new immunoassay for PSA is validated by labelling ALP on PSA antibody. The low detection limit of 0.04 ng mL−1 in detecting PSA is appropriate for PSA detection in real samples. Therefore, the work not only establishes a new strategy for ALP and PSA determination, but also provides a new conception for putting photoinduced oxidase-like fluorescein in practical application.

A novel ultrasensitive sandwich-type photoelectrochemical immunoassay for PSA detection based on dual inhibition effect of Au/MWCNTs nanohybrids on N-GQDs/CdS QDs dual sensitized urchin-like TiO2

Abstracts An ultrasensitive sandwich-type photoelectrochemical immunosensor (PEC) was designed successfully for the quantify detection of prostate specific antigen (PSA). Here, urchin-like TiO2, which was dual sensitized by N-doped graphene quantum dots (N-GQDs) and CdS quantum dots (QDs), were fixed on the surface of ITO electrode and produced a significant photocurrent signal. The TiO2/N-GQDs/CdS QDs composite was not only could use as an excellent photoactive substrate but also could provide abundant functional group to immobilized PSA antibodies (Ab1). Using Au/MWCNTs nanohybrids as the label of the secondary antibody (Ab2), Au nanoparticles (NPs) and CdS QDs generated excition-plasmon interactions, and Au NPs produced surface plasmon resonance under photoexcitation. Meanwhile along with the energy transfer process, the photocurrent was inhibited which results in an increase in the sensitivity of the immunosensor. In addition, the loading amount of the labeled Ab2 could be increased due to the large surface area of Au/MWCNTs, the photocurrent signal was further reduced after the specific immune recognition. Under the optimal performance, the sandwich immunosensor proved an ideal linear relationship ranging from 0.1 pg/mL to 50 ng/mL and the detection limit was 6.16 fg/mL with good sensitivity and stability, which provided a promising PEC platform and valuable referential idea for the detection of other trace tumor markers.

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 electricalinsulation 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 -0.08V (vs. Ag/AgCl), has a low limit of detection (4.4fg·mL-1) and a wide linear range (0.1pg·mL-1 to 20ng·mL-1). This meets the demands of clinical diagnosis (with values <4ng·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.

Highly-sensitive SERS-based immunoassay platform prepared on silver nanoparticle-decorated electrospun polymeric fibers

A new, highly sensitive surface enhanced Raman scattering (SERS)-based immunoassay platform was prepared using silver nanoparticle (AgNP)-decorated electrospun fibers as the capture substrate. We used electrospinning and silver mirror reaction to generate AgNP-decorated polycaprolactone (PCL) fiber matrix (Ag-PCL). The resultant capture substrates obtained were bi-directionally porous, free-standing, and flexible. AgNP formation on the PCL fibers was confirmed via SEM, AFM, XPS, and TGA analysis. In addition, gold nanoparticles immobilized with a Raman reporter, 4-mercaptobenzoic acid (4-MBA), were prepared as the SERS tag. This tag could significantly enhance the SERS signal via generation of additional hot spots between AgNPs on fibers and AuNPs. For a model immunoassay to detect prostate specific antigen (PSA), PSA antibodies were immobilized on both Ag-PCL and AuNP SERS tags. The large surface area of fiber substrates allowed the immobilization of large amounts of antibodies and their porous structures facilitated the assessment of the target antigen to immobilized antibodies. Binding of PSA between antibodies on AgNPs and AuNPs led to formation of a sandwich structure by the two metal nanostructures, and consequently, highly sensitive detection of PSA was possible up to a detection limit of 1pg/mL within 1h of reaction time. The developed SERS-based immunoassay platform produced uniform and reproducible SERS signals over the entire substrate area and from different samples.

Label-free electrochemiluminescent immunosensor for prostate specific antigen ultrasensitive detection based on novel luminophore Ag3PO4 decorated GO

A label-free electrochemiluminescence (ECL) sensor having high sensitivity was operated for detection of prostate specific antigen (PSA) by using silver/silver orthophosphate/graphene oxide composites (Ag/Ag3PO4/GO) as antibody carriers and sensing platform. Firstly, nanoparticles of Ag3PO4 were employed as luminescent materials for solid-state ECL detection and to propose possible luminescence route in this study. GO, having the ultrahigh specific surface area and superior conductivity, was utilized as a loading matrix for nanoparticles of Ag3PO4. It was employed not only to contribute for the enhancement of electrons transfer for the whole ECL system, but also further improvement of the sensitivity of the immunosensor. Given that the spectacular biocompatibility of silver nanoparticles (Ag NPs) was used to immobilize PSA antibody (anti-PSA) via the covalent coupling between silver and amino group, to improve immunosensor sensitivity. The proposed sensing platform presented tremendous cathodic ECL performance and better response to the PSA. Under optimized experimental conditions, the proposed immunosensor displayed a calibration range of 0.001–80ng/mL and low detection limit of 0.3pg/mL (S/N=3) for PSA determination. Featuring encouraging selectivity, repeatability, and stability, the fabricated Ag/Ag3PO4/GO is anticipated to glare novel ECL biosensor platform for PSA and other biomarkers detection in the real sample.

Dual-modality impedimetric immunosensor for early detection of prostate-specific antigen and myoglobin markers based on antibody-molecularly imprinted polymer

A new dual-modality immunosensor based on molecularly imprinted polymer (MIP) and a nanostructured biosensing layer has fabricated for the simultaneous detection of two important markers including prostate-specific antigen (PSA) and myoglobin (Myo) in human serum and urine samples. In the first step, 3,3′-dithiodipropionic acid di(N-hydroxysuccinimide ester) (DSP) was self-assembled on a gold screen printed electrode (SPE). Then, the target proteins were attached covalently to the DSP-SPE. The imprinted cocktail polymer ((MIP(PSA, Myo)-SPE)) was synthesized at the SPE surface using acrylamide as monomer, N,N′-methylenebisacrylamide as a crosslinker, and PSA and Myo as the templates, respectively. The MIP-SPE was specific for the impedimetric sensing of PSA and Myo. After that, a nanocomposite (NCP) was synthesized based on the decorated magnetite nanoparticles with multi-walled carbon nanotube, graphene oxide and specific antibody for PSA (Ab). Then, NCP incubated with (MIP(PSA, Myo)-SPE. The modified electrodes and synthesized nanoparticles were characterized using electrochemical impedance spectroscopy, dynamic light scattering, surface plasmon resonance and scanning electron microscopy. The limits of detections were found to be 5.4 pg mL−1 and 0.83 ng mL−1 with the linear dynamic ranges of 0.01–100 and 1–20000 ng mL−1 for PSA and Myo, respectively. The ability of proposed biosensor to detect PSA and Myo simultaneously with high sensitivity and specificity offers a powerful opportunity for the new generation of biosensors. This dual-analyte specific receptors-based device is highly desired for the integration with lab-on-chip kits to measure a wide panel of biomarkers present at ultralow levels during early stages of diseases progress.

An electrochemical biosensor for prostate cancer biomarker detection using graphene oxide-gold nanostructures.

In this paper, a most sensitive electrochemical biosensor for detection of prostate-specific antigen (PSA) was designed. To reach the goal, a sandwich type electrode composed of reduced graphene oxide/ gold nanoparticles (GO/AuNPs), Anti-Total PSA monoclonal antibody, and anti-Free PSA antibody was assembled. The functionalized materials were thoroughly characterized by atomic force microscope spectroscopy, transmission electron microscopy, and X-ray diffraction techniques. The electrochemical properties of each of the modification step were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. The results presented that the proposed biosensor possesses high sensitivity toward total and free PSA. Furthermore, the fabricated biosensor revealed an excellent selectivity for PSAin comparison to the other tumor markers such as BHCG, Alb, CEA, CA125, and CA19-9. The limit of detection for the proposed electrochemical biosensor was estimated to be around 0.2 and 0.07ng/mL for total and free PSA antigen, respectively.

Highly sensitive AlGaN/GaN HEMT biosensors using an ethanolamine modification strategy for bioassay applications.

In this paper, we propose a highly efficient surface modification strategy on an AlGaN/GaN high electron mobility transistor (HEMT), where ethanolamine (EA) was utilized to functionalize the surface of GaN and provided amphoteric amine groups for probe molecular immobilization for bioassay application. The molecular gated-AlGaN/GaN HEMT was utilized for pH and prostate-specific antigen (PSA) detection to verify its performance as a biosensor. Benefitting from the high coating quality on the GaN surface, the performance of our biosensor is drastically improved compared to other AlGaN/GaN HEMT based pH and PSA biosensors reported before. Our molecular gated-AlGaN/GaN HEMT biosensor has achieved good static electrical performance for pH sensing, such as high sensitivity, good linearity and chemical stability. Moreover, after further immobilization of PSA antibody onto the EA aminated GaN surface, the limit of detection (LOD) for PSA detection is as low as 1 fg mL−1 in PBS buffer, which has reached an at least two orders of magnitude decrease compared to any other AlGaN/GaN HEMT based PSA biosensor reported before. And the sensitivity of our PSA biosensor has achieved a substantial increase, reaching up to 2.04% for 100 ng mL−1. The measurements of pH and PSA utilizing the EA modified AlGaN/GaN HEMT biosensor indicate that the surface modification strategy on the GaN proposed in this paper can effectively improve the performance of the AlGaN/GaN HEMT based biosensor, which demonstrates a promising application prospect in the AlGaN/GaN HEMT based biological detection field.

Electrochemiluminescent immunosensor for prostate specific antigen based upon luminol functionalized platinum nanoparticles loaded on graphene

A novel label-free electrochemiluminescent (ECL) immunosensor based upon luminol functionalized platinum nanoparticles loaded on graphene sheets (Lu-Pt@GS) as sensing platform was fabricated for highly sensitive and selective determination of prostate specific antigen (PSA). In this work, for the first time luminol was employed as both ECL luminescence reagent and reductants to in-situ reduce H2PtCl6 forming Pt NPs on surface of GS. A great deal of luminol could be attached onto the surface of Pt NPs within the reduction process, which can generate strong ECL emission. Pt NPs not only could enhance ECL signals of luminol but supply active sites for the immobilization of PSA antibodies with micro friendly environment. For preventing the consecutive reaction among luminol and H2O2, single-step cycle pulse was adopted, resulting in stable and strong ECL signals. Under optimized experimental conditions, the proposed ECL immunosensor acquired a wide linear range of 1 pg/mL to 10 ng/mL with a relatively low detection limit of 0.3 pg/mL for PSA. Furthermore, due to high sensitivity, simplicity and cost-effectiveness, the designed immunosensor provides a new method for detecting other important biomarkers in clinical analysis.

High Sensitive Detection of Prostate Specific Antigen by Using Ferrocene Cored Asymmetric PAMAM Dendrimer Interface Screen Printed Electrodes

AbstractIn this study, electrochemical immunosensors were developed for the detection of prostate specific antigen (PSA) using ferrocene (Fc) and polyamidoamine dendrimer (PAMAM) constructs. The biosensor fabrication was designed by modifying the screen‐printed gold electrode (Au) with ferrocene cored dendrimers (FcPAMAM) synthesized in three different generations. The self‐assembled monolayer principle was followed, to obtain sensitive, selective and disposable electrodes. Therefore, the Au electrodes were modified with cysteamine (Cys) to obtain a functional surface for FcPAMAM dendrimers to bind. Dendrimer generations were attached to this surface using a cross‐linker (glutaraldehyde) so that a suitable surface was obtained for binding of biological components. The Monoclonal PSA antibody (anti‐PSA) was immobilized on the Au electrode surface which coated with dendrimer, and (Au/Cys/FcPAMAM/anti‐PSA) biosensing electrode was obtained. The PSA detection performances of electrochemical impedance spectroscopy (EIS) and Amperometry based immunosensors exhibited very low detection limits; 0.001 ng mL−1 and 0.1 pg mL−1, respectively. In addition, EIS and Amperometry based biosensors using Au/Cys/FcPAMAM/anti‐PSA sensing electrode were represented excellent linear ranges of 0.01 ng mL−1 to 100 ng mL−1 and 0.001 ng mL−1 to 100 ng mL−1. In order to determine the applicability recovery and selectivity tests were performed using three different proteins in human serum.

Label‐free Voltammetric Immunosensor for Prostate Specific Antigen Detection

AbstractThis work describes a sensitive voltammetric immunosensor for label‐free electroanalysis of the prostate specific antigen (PSA), the main biomarker of prostate cancer. A gold electrode was firstly modified with the optimum self‐assembled monolayer (SAM), 1,6‐hexanedithiol, followed by the subsequent adsorption of gold nanoparticles (AuNPs) and, then, the monoclonal antibody to recognize PSA was immobilized. The influence of the most significant experimental variables (SAM type and incubation time, AuNPs deposition, antibody concentration and bovine serum albumin immobilization) on the biosensor response was studied by microscopy and voltammetry techniques. The electroanalytical detection was based on the interaction between PSA antibody and PSA via square‐wave voltammetry using ferrocyanide/ferricyanide as electrochemical redox indicator. Using the proposed immunosensor, PSA was specifically detected within the linear range between 0.2 and 200 ng mL−1 with 0.01 ng mL−1 as limit of detection. The immunosensor allows accurate, reproducible and sensitive (22.7 % reduction mL ng−1) detection in a concentration range useful for clinical purposes.

Formation of Homogeneous Epinephrine-Melanin Solutions to Fabricate Electrodes for Enhanced Photoelectrochemical Biosensing.

The development of a simple but effective surface modification method is very important for the construction of biosensing interfaces. In this work, a postsynthetic water-soluble epinephrine-melanin (EPM) prepared from the self-polymerization of epinephrine has been demonstrated as an alternative of the widely used in situ formed polydopamine (PDA) for the surface coating of TiO2 nanoparticles and the construction of a photoelectrochemical (PEC) biosensing interface. In contrast to the formation of insoluble aggregates in solution for dopamine, a homogeneous solution was obtained for epinephrine after the self-polymerization. The use of EPM as a postsynthetic material enables the surface coating of TiO2 with the simple drop-casting method. Compared with the widely used dip-coating method for in situ PDA modification, the developed drop-casting method based on the use of water-soluble postsynthetic EPM saves more time, avoids the waste of bulk solution, and undoubtedly decreases the batch-to-batch inconsistencies. The simple coating of commercially available TiO2 nanoparticles with EPM greatly enhances the PEC performance due to the charge transfer property of EPM. The application of EPM in the construction of the PEC biosensing interface was demonstrated by the immobilization of a model biorecognition element (prostate specific antigen (PSA) antibody) onto EPM modified indium tin oxide (ITO) photoanode. Sensitive detection of PSA with high selectivity and stability was obtained on the basis of the biological recognition ability of PSA antibody. This work may renew the use of postsynthetic melanin-like biopolymers in other fields.

Spatial-Resolved Photoelectrochemical Biosensing Array Based on a CdS@g-C3N4 Heterojunction: A Universal Immunosensing Platform for Accurate Detection.

The detection of biomarkers with high sensitivity and accuracy in real biosamples remains challenging. Herein, a universal spatial-resolved photoelectrochemical (PEC) ratiometry for biodetection of prostate-specific antigen (PSA) as model biomarker was designed for the first time based on a dual-electrode array modified by CdS@g-C3N4 heterojunction coupled with CuS quantum dots (QDs) as signal amplification tags. Specifically, a new kind of photoactive material, the CdS@g-C3N4 p-n heterojunction with high photoelectric conversion efficiency and good chemical stability, was synthesized and immobilized on two spatial-resolved electrodes (WE1 and WE2). After immobilizing gold nanoparticles and capturing PSA antibodies on the electrodes, WE1 incubated with various concentrations of PSA was taken as a working electrode, whereas WE2 with a fixed concentration of PSA was used as an internal reference electrode. Next, signal antibodies of PSA-labeled CuS QDs as PEC signal quenchers were immobilized on the electrodes to form a sandwich-type immunocomplex. With the aid of a multiplexed disjunctor, the PEC responses of the dual electrodes were recorded, and the PSA was quantified via the ratio values of photocurrent intensities from WE1 and WE2. Combining the fine PEC performance of the CdS@g-C3N4 heterojunction with the superior quenching effect of CuS QDs in the spatial-resolved platform, the ratiometric system exhibits a linear range from 1.0 × 10-11 to 5.0 × 10-8 g mL-1 with a limit of detection of 4.0 pg mL-1. The results demonstrated herein may provide a new pattern for biomarker detection with high accuracy and good specificity as well as satisfactory applicability in real biosamples.

Screen Printed Gold Electrode with Cysteamine and Single Walled Carbon Nanotubes for the Recognition of Prostate Specific Antigen

During the development of highly sensitive and stable immunosensors, it is requisite to create new types of electrodes that allow for fast and simple measurements of specific biological interactions. In the present study, gold screen printed electrode platform was modified and functionalized by Self Assembled Monolayer (SAM) and Single walled Carbon nanotubes (SWNTs) is done for the immunosensing of Prostate Specific Antigen (PSA). On the modified electrode, monoclonal Antibody (mAb) of PSA were immobilized which reacts with PSA antigen in the sample and corresponding current signals were measured by Differential Pulse voltammetry (DPV) and Electrochemical Impedance Spectroscopy (EIS) with the help of electrochemical work station.

Spatial-resolved dual-signal-output electrochemiluminescent ratiometric strategy for accurate and sensitive immunoassay

The identification of tumor markers is of great importance for clinical diagnosis but accurate detection with high sensitivity is still a great challenge. In present work, a spatial-resolved dual-signal-output electrochemiluminescent (ECL) ratiometric assay platform was constructed for sensitive detection of prostate specific antigen (PSA) on a dual-disk glassy carbon electrode. To fabricate the platform, flower-like CdS three-dimensional (3D) assemblies and Ru(bpy)32+-conjugated silica nanoparticles (Ru(bpy)32+@RuSi NPs), were immobilized onto the two disks as cathodic and anodic ECL emitters, respectively. After the stepwise modification of the gold nanoparticles, antibody for PSA, and bovine serum albumin onto the two disks respectively, the Ru(bpy)32+@RuSi NPs-based disk were incubated with varied concentration of PSA as working electrode, whereas the flower-like CdS 3D assemblies-based disk with fixed concentration of PSA were taken as internal reference electrode. The label free assay of PSA was realized by the ratio of anodic ECL signal from working electrode to the cathodic ECL signal from the internal reference electrode (ECLanode/ECLcathode). On the basis of the spatial-resolved dual-signal-output ratiometric ECL sensor, the PSA can be detected accurately with a linear range of 0.001 – 50ng/mL at a concentration as low as 0.34pg/mL. Furthermore, the proposed method was applied for PSA determination in human serum samples with satisfying results. Thanks to the same modified process of the two disks, this universal design well avoids environmental errors including the interference caused in the biological recognition process, which effectively reduces the false positive or negative errors, exhibiting a greatly improved accuracy, reliability and sensitivity.

Detection of early stage prostate cancer by using a simple carbon nanotube@paper biosensor

This study is an investigation for an inexpensive, simple and sensitive biosensor to detect prostate cancer using bioactivated-multi wall carbon nanotubes (MWCNTs, diameter of 20nm, length of 5µm) and a micro-pore filter paper (pore size of 0.45µm). For the immunoassay of prostate specific antigen (PSA), which is a biomarker of prostate cancer, MWCNTs were activated with PSA antibody (monoclonal antibody of the prostate specific antigen) by using N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide sodium salt (NHSS). The activated MWCNTs were deposited on the micro-pore filter paper to use as a biosensor. The prepared biosensor can assay from 0 to 500ng/mL of PSA level within 2h with the detection limit of 1.18ng/mL by the measurement of resistance change. The resistance change was caused by site selective interaction between PSA and PSA-antigen with an inexpensive bench top digital multimeter (5 1/2 digits). The detection range and sensitivity of the prepared sensor are good enough to diagnose the early stage of prostate cancer (> 4ng/mL of PSA). This paper-based biosensor is about 20 times cheaper (fabricated biosensor price: 2.4 $) and over 10 times faster than enzyme-linked immunosorbent assay (ELISA), which is a general method for the detection of a specific protein in the modernized hospitals. Furthermore, the maximum detection limit is about 50 times higher than ELISA.

Electrochemical sandwich immunoassay for the prostate specific antigen using a polyclonal antibody conjugated to thionine and horseradish peroxidase

The authors present a voltammetric immunoassay for the quantification of the prostate specific antigen (PSA), a well-established tumor marker. Biotinylated anti- PSA antibodies were immobilized on the surface of a nano-TiO2-modified carbon paste electrode using specific interaction between streptavidin and biotin. Streptavidin itself was covalently grafted to the electrode surface via 4-aminobenzoic acid film. Signal transduction was then performed using polyclonal antibodies conjugated with horseradish peroxidase (HRP) and thionine. An amplified catalytic reduction current was observed in the presence of H2O2 because more than one polyclonal antibody linked to each antigen. Each step of the preparation of the immunosensor was monitored via electrochemical impedance spectroscopy. The electrode, if operated at a typical potential of 0.3 V vs. Ag/AgCl and using hexacyanoferrate as an electrochemical probe, exhibits linear responses in the 0.10 to 5.0 ng·mL−1 and 5.0 to 100 ng·mL−1 PSA concentration ranges, with a detection limit of 200 pg·mL−1. The accuracy of the biosensor was confirmed by analyzing a certified human serum sample, and this indicated that the immunosensor is well suited for the quantification of PSA.

Presence of PSA antibodies in seminal plasma of infertile men.

Immunoinfertility due to antisperm antibodies and semen hyperviscosity are among major causes of male infertility. Although the modulation of prostate-specific antigen (PSA) has been investigated in prostate abnormalities, its role and the effect of its dysfunction in male fertility/infertility have not been extensively examined. The present study was conducted to examine the presence of PSA antibodies locally in the seminal plasma of men having immunoinfertility and semen hyperviscosity. Seminal plasma samples from immunoinfertile men (n=25), men with hyperviscous semen (n=25), and normal men (n=24) were collected and analyzed for immunoreactivity with PSA in ELISA and Western blot. In the immunoinfertile group, seminal plasma from 20% of men reacted positively with PSA. In the hyperviscous group, seminal plasma from 28% of men reacted positively with PSA. None (0%) of the seminal plasma from the normal group showed immunoreactivity to PSA. This is the first study ever to indicate the presence of PSA antibodies in semen of men having immunoinfertility or hyperviscosity. These findings may have clinical significance in the specific diagnosis and treatment of infertility in men and contraceptive vaccine development.