Prostate-specific Antigen Immunoassays Research Articles

Synergistic enhancement mediated sensitive SERS-based immunoassay of PSA using versatile PDMS@AgNPs@ZIF-67 biomimetic substrates

Among various biomimetic polymer materials, polydimethylsiloxane (PDMS) stands out as an ideal matrix for surface-enhanced Raman scattering (SERS) due to its unique intrinsic Raman signal and tenacity. In order to realize the precise detection of prostate-specific antigen (PSA), we proposed a sandwich-type SERS-active immunostructure composed of PDMS@silver nanoparticles (Ag NPs)@ZIF-67 biomimetic film as the immunosubstrate and gold nanorods (Au NRs) as immunoprobes. Due to the synergistic effect of electromagnetic enhancement facilitated by biomimetic surfaces and chemical enhancement achieved by ZIF-67, this structure enabled an ultrasensitive and selective detection of PSA across a broad range from 10−3 to 10−9 mg/mL. The achieved limit of detection was as low as 3.0 × 10−10 mg/mL. Particularly, the intrinsic Raman signal of PDMS matrix at 2905 cm−1 was employed as a potential internal standard (IS) in the detection, achieving a high coefficient of determination (R2) value of 0.996. This multifunctional SERS substrate-mediated immunoassay holds vast potential for early diagnosis of prostate cancer, offering promising prospects for clinical applications.

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.

Kinetic Analysis of Prostate-Specific Antigen Interaction with Monoclonal Antibodies for Development of a Magnetic Immunoassay Based on Nontransparent Fiber Structures.

Prostate cancer is the second most common cancer diagnosed in men worldwide. Measuring the prostate-specific antigen (PSA) is regarded as essential during prostate cancer screening. Early diagnosis of this disease relapse after radical prostatectomy requires extremely sensitive methods. This research presents an approach to development of an ultrasensitive magnetic sandwich immunoassay, which demonstrates the limit of PSA detection in human serum of 19 pg/mL at a dynamic range exceeding 3.5 orders of concentration. Such attractive performance stems, inter alia, from the kinetic analysis of monoclonal antibodies (mAbs) against free PSA to select the mAbs exhibiting best kinetic characteristics and specificity. The analysis is carried out with a label-free multiplex spectral-correlation interferometry compatible with inexpensive single-use glass sensor chips. The high sensitivity of developed PSA immunoassay is due to electronic quantification of magnetic nanolabels functionalized by the selected mAbs and three-dimension porous filters used as an extended solid phase. The assay is promising for PSA monitoring after radical prostatectomy. The proposed versatile approach can be applied for the rational design of highly sensitive tests for detection of other analytes in many fields, including in vitro diagnostics, veterinary, food safety, etc.

Nonlinear hybridization chain reaction-based flow cytometric immunoassay for the detection of prostate specific antigen

Sensitive detection of biomarkers is highly desirable for disease diagnosis and postoperative examination. As a signal amplification technique, nonlinear hybridization chain reactions (NHCR) based on DNA self-assembly has been widely adopted to versatile biosensor platforms for signal output and sensitivity enhancement. Herein, we proposed a novel hairpin-free NHCR based flow cytometric immunoassay for prostate specific antigen (PSA) detection. In this study, Ab1-Ag-Ab2-streptavidin-trigger DNA complexes were formed on the magnetic beads (MBs), and each trigger DNA initiated a round of NHCR amplification to form dendritic DNA nanostructures with many fluorescent signal molecules. The robust flow cytometric fluorescent analysis was finally employed for the quantitation of target protein on the MBs. As far as we know, this is the first time to combine the hairpin-free NHCR strategy with fluorescent immunoassay on MBs to detect protein biomarkers. In addition to the high selectivity of immunoassay itself, the characteristics of isothermal, enzyme-free, and exponential amplification efficiency of hairpin-free NHCR endow this developed immunoassay with a detection limit that exceeds 100-folds that of commercially available PSA kits. Moreover, this MBs-based platform of this immunoassay is also amenable to target enrichment and removal of spontaneous NHCR signal through magnetic separation, greatly eliminating the background signal interference. With our efforts, this newly developed biosensor exhibits a detection limit of 1.92 pg/mL and shows high selectivity. It has also been successfully applied to the quantitative detection of PSA in serum samples. With these merits, this convenient biosensor platform has the potential for medical research and disease diagnosis.

Pearson's principle-inspired hollow metal sulfide for amplified photoelectrochemical immunoassay for disease-related protein

Designing a universal route for rational synthesis of a family of hollow multinary chalcogenide semiconductors for photoelectrochemical biosensors is still facing to the enormous challenges ahead. Herein a template-assisted Cu2O surface vulcanization and etching through a Pearson's hard and soft acid-base (HSAB) principle was utilized to synthesize hollow Cu2-xS photoactive materials for photocurrent detection of prostate-specific antigen (PSA). We initially synthesized cubic Cu2O and further surface sulfidation and HCl etching to obtain cubic Cu2-xS. Inspiringly, stirring of CuS, phosphine (TBP: tributylphosphine) and other metal salts could replace Cu+ ions to obtain new metal sulfides without changing the framework, size and thickness of the original material. This interesting phenomenon could be explained by HSAB theory, which soft base was favorable for combining soft acid (Cu+) to drive Cu+ out of the framework. Based on the results, HSAB-based reaction system was applied to develop novel photoelectrochemical PSA immunoassay. Polymetallic-doped sulfides (ZnxCd1-xS) had better photocurrent response than pure binary sulfides. A copper oxide (CuO)-labeled detection antibody is captured in a microplate along with a sandwich immunoassay in the presence of target PSA. Subsequently, the CuO nanoparticles were dissociated by hydrochloric acid, releasing a large amount of copper ions to participate in the cation exchange reaction with ZnxCd1-xS. Such excellent photoelectric conversion materials could sensitively detect target PSA with a wide linear range from 1.0 pg/mL to 10 ng/mL at a limit of detection down to 0.32 pg/mL. Additionally, favorable stability, great anti-interference ability, easy-fabrication, low-cost, and satisfactory accuracy for the analysis of actual samples were acquired. Importantly, the concept of cation exchange reaction can be widely used to synthesize advanced nanomaterials for fabrication of high-efficiency biosensing systems.

Responsive-released strategy based on lead ions-dependent DNAzyme functionalized UIO-66-NH2 for tumor marker

Signal labeling on electrode interface is an important step during the construction of immunosensor and most signal substances are directly affixed on the immunoprobe or substrate so that some problems such as flimsy labeling method and interference of insulating proteins on electrode surface have been existed to affect their readout. In order to solve above problems in electrochemical immunoassay, a lead ions-decodable autocephalous signal integrator based on UIO-66-NH2 was proposed for the detection of prostate specific antigen (PSA). Briefly, a lead ions-dependent DNAzyme functionalized UIO-66-NH2, in which methylene blue was encapsulated, was independently dispersed in solution phase to be closely associated with the lead sulfide labeled sandwich bioconjugates, and internal methylene blue molecules can be sustained released once a cationic exchange reaction was occurred between lead sulfide label and adscititious silver ions. Based on this designing, immunoassay for PSA was effectively connected with the dynamic behavior of methylene blue molecules through the cleavage of DNAzyme on MOFs surface and performed a wide linear range from 1 pg mL−1 to 10 ng mL−1 and a satisfactory detection limit with 0.34 pg mL−1. The proposed strategy was expected to offer more valuable information for the application of MOFs in early and accurate cancer diagnosis.

Light Absorption Measurement With a CMOS Biochip for Quantitative Immunoassay Based Point-of-Care Applications.

We present a CMOS biochip-based photometer for quantitative immunoassay diagnostics. The photometer quantifies the concentration of antigens based on light absorption, which allows for a low-cost implementation without expensive optical components. We propose a light controller to lower the start-up and settling time of the light source to 30 seconds, to facilitate fast measurement starts, and to decrease the overall measurement times. The application-specific integrated circuit (ASIC) contains a 6 x 7-sensor array with 100 μm x 100 μm photodiodes that serve as signal transducers. The ASIC was developed in a normal 0.35- μm CMOS technology, avoiding the need for expensive post-CMOS processes. We present our strategy for the assembly of the ASIC and the immobilization of antibodies. For its first time, we demonstrate the quantification of prostate specific antigen (PSA) with an optoelectronic CMOS biochip using this approach. A PSA immunoassay is performed on the top surface of the CMOS sensor array, enzyme kinetics and PSA concentration are measured within 6 minutes with a limit of detection (LoD) of 0.5 ng/ml, which meets clinical testing requirements. We achieve an overall coefficient of variation (CV) of 7%, which is good compared to other point-of-care (PoC) systems.

Ionic liquid-assisted chemiluminescent immunoassay of prostate specific antigen using nanoceria as an alkaline phosphatase-like nanozyme label.

An alkaline phosphatase-like nanozyme was applied for an immunoassay for the first time. By using nanoceria as the alkaline phosphatase-like catalytic label and CDP-star as the substrate, the chemiluminescent detection of prostate specific antigen was demonstrated. More importantly, the addition of ionic liquid can significantly increase the sensitivity of the immunoassay. With the aid of ionic liquid, an order of magnitude improvement in the sensitivity was achieved with a detection limit of 53 fg mL-1.

A sensitive paper-based lateral flow immunoassay platform using engineered cellulose-binding protein linker fused with antibody-binding domains

An advanced paper-based LFIA using engineered cellulose-binding protein linker fused with antibody-binding domains was developed to resolve problems associated with conventional LFIA strip, including the limitation of quantitative analysis and low sensitivity. CBP31-BC linker was prepared by genetically fusing the cellulose-binding modules of family 3 (CBM3) and family 1 (CBM1) with antibody-binding B and C domains of Protein A. Cellulose-binding analysis showed that the addition of two CBMs led to high cellulose-binding capacity in CBP31-BC. Transmission electron microscopy and quartz crystal microbalance analyses demonstrated that the cellulose-binding ability of CBP31-BC enabled the BC domain to be efficiently exposed, allowing about 6-fold higher antibody-binding efficiency (∼32.5 %) than that (∼5.5 %) of sole BC. To evaluate the feasibility of the CBP31-BC linker-employed LFIA platform, an immunoassay of prostate-specific antigen (PSA) was performed as a model reaction. The CBP31-BC-employed paper-based LFIA detected PSA at levels as low as 0.25 ng/mL in 20 min, which is about 10-fold more sensitive to conventional LFIAs that use simple physical adsorption. CBP31-BC-employed LFIA also exhibited a lower detection range of 0.25–2.5 ng/mL when compared to conventional LFIAs. These results might be due to efficient oriented immobilization of the capture antibody by CBP31-BC linker on cellulose membrane. Thus, our developed CBP31-BC linker-employed paper-based LFIA platform holds great promise for the detection of target markers due to significantly enhanced sensitivity.

Ultrasensitive ratiometric photoelectrochemical immunoassay for prostate specific antigen based on nanoscale heterojunction

A new photoelectrochemical (PEC) immunosensor is fabricated for the ultrasensitive detection of prostate-specific antigen (PSA). Nanoscale poly(indole-5-carboxylic acid) (P5ICA)/WO3 p-n type heterojunction is firstly used as the photoactive material with good photoelectric activity and chemical stability. The energy level matching effect between P5ICA and WO3 is conducive to the generation of stronger photocurrent signals. The sensitization effect of this heterojunction can also increase the absorption range of visible light and improve the utilization of light. This ratiometric device includes detection section (DS) and reference section (RS), which are equipped on a single FTO electrode. DS incubates with different concentrations of PSA, and RS incubates with a constant concentration of PSA. Thus, the ultrasensitive ratiometric detection of PSA is achieved by the ratio value of photocurrents (DS/RS), reducing the impact of external factors on detection results effectively. This sensor exhibits a dynamic working range between 0.0005−50 ng mL−1 with a limit of detection (LOD) of 0.00012 ng mL−1 and a limit of quantification (LOQ) of 0.0004 ng mL−1. In addition, this sensor has high selectivity, good portability and acceptable detection accuracy in actual samples, which indicates potential applications for detection of disease-related biomarkers.

Recyclable label-free SERS-based immunoassay of PSA in human serum mediated by enhanced photocatalysis arising from Ag nanoparticles and external magnetic field

In the field of SERS-based immunoassay, the recyclable utilization of noble metal materials is essential for their practical application in clinical medicine. Herein, a kind of novel multifunctional Fe3O4@TiO2@Ag microparticles (MPs) was synthesized through a poly-step reaction, and then their feasibility for recyclable label-free SERS-based immunoassay of prostate specific antigen (PSA) was demonstrated. The photocatalytic efficiency of the Fe3O4@TiO2@Ag MPs was fully adjusted by tuning the thickness of the middle TiO2 shell and the areal density of the outside Ag NPs. Particularly, the Fe3O4 core played a critical role in further improving the photocatalytic activity under external magnetic field. Thereafter, the successfully photocatalytic degradation and recyclable detection of PSA in human serum was confirmed by the change of O 1s, N 1s, and C 1s signals in the XPS characterization and a limit of detection as low as 16.25 pg/mL was realized. Furthermore, the quantitative recyclable detection of PSA in clinical serum samples with prostate cancer was conducted, and the results are basically consistent with those of the traditional chemiluminescent immunoassay, showing small relative deviation less than or equal to 5.7%.

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.

DNA Nanofirecrackers Assembled through Hybridization Chain Reaction for Ultrasensitive SERS Immunoassay of Prostate Specific Antigen.

Isothermal nucleic acid amplification technology has been widely adopted for analytical chemistry with the purpose of sensitivity improvement. Herein we present an ultrasensitive concatenated hybridization chain reaction (C-HCR) based surface-enhanced Raman scattering (SERS) immunoassay by forming antibody-antigen-aptamer heterosandwich structures with the model analyte of total prostate specific antigens (tPSA). In the C-HCR, two HCRs, one proceeds with two hairpins and the other with four biotin-modified hairpins, are coupled, making the formation of DNA nanofirecrackers with the lengths longer than 200 nm and more than four hundred million binding sites of streptavidin modified enzymes. These types of DNA nanofirecrackers through the aptamer encoded linker strand to form heterosandwich structures could provide a general signal application platform such as enzyme catalysis with high amplification efficiency. As a proof of concept, the Au@Ag core-shell nanostructure based SERS immunoassay with excellent signal amplification has been developed by employing the streptavidin modified alkaline phosphatase (SA-ALP) through its catalysis of 2-phospho-l-ascorbic acid trisodium salt (AAP) to form Au@Ag core-shell nanostructures via the formation of ascorbic acid (AA) to reduce AgNO3 and deposition of silver element on gold nanorods (AuNRs). The newly developed method has a detection limit as low as 0.94 fg/mL and has successfully achieved the detection of serum samples from clinical patients, which was consistent with the clinical test results, showing that this C-HCR strategy to form DNA nanofirecrackers has great potential in clinical applications.

Hierarchical Ti3C2 MXene-derived sodium titanate nanoribbons/PEDOT for signal amplified electrochemical immunoassay of prostate specific antigen

Two-dimensional (2D) MXenes have emerged as an attractive platform to construct electrochemical biosensors because of their excellent electronic properties. However, the self-restacking and agglomeration of MXenes lead to unsatisfactory performance. To overcome these drawbacks, herein, the treatment of Ti3C2 MXene through a simultaneous oxidation and alkalization progress was proposed for the synthesis of 3D sodium titanate nanoribbons (M-NTO). Furthermore, conductive poly(3,4-ethyl-enedioxythiophene) (PEDOT) was anchored on 3D M-NTO to enhance its conductivity. The resulting M-NTO-PEDOT composite possessed high specific surface area, fast electron transfer ability, as well as excellent biocompatibility. Subsequently, Au nanoparticles (AuNPs) were electrodeposited on the surface of M-NTO-PEDOT for prostate specific antigen (PSA) antibodies immobilization. Thus, a facile electrochemical label-free immunosensor for sensitive detection of PSA was fabricated on a basis of AuNPs/M-NTO-PEDOT composite. Benefitting from the synergistic effects of M-NTO, PEDOT and AuNPs, the fabricated M-NTO-PEDOT based immunosensor exhibited good analytical performance with a low limit of detection (LOD) of 0.03 pg L−1 (S/N = 3). Additionally, high stability, good selectivity and recovery were achieved in the process of PSA detection in human serum samples.

Highly sensitive piezoelectric immunosensors employing signal amplification with gold nanoparticles

We present a quartz crystal microbalance (QCM) immunosensor for highly sensitive detection of prostate-specific antigen (PSA) in a human serum immunoassay. In particular, in this study, we employed signal amplification using and enlarging gold nanoparticles. Because QCM measures the change of resonance frequency according to the mass change occurring on the sensor surface, we could quantitatively analyze PSA based on a tremendous increase in mass by sandwich immunoassay using AuNP-conjugated anti-PSA-detecting antibody enhanced with subsequent gold staining. The limit of detection of the PSA immunoassay in human serum without gold staining enhancement was 687 pg ml−1 but was 48 pg ml−1 with the gold staining-mediated signal amplification. That is, amplifying the signal resulted in increased sensitivity and reproducibility of immunoassay in a human serum.

Does seminal vesicle-sparing robotic radical prostatectomy influence postoperative prostate-specific antigen measured with an ultrasensitive immunoassay?

PURPOSE Sparing of the seminal vesicles during robotic radical prostatectomy (SVRP) is an attempt to reduce potential damage to the hypogastric pelvic nerves. However, the seminal vesicles are known to express prostate-specific antigen (PSA) and it is unknown whether SVRP influences oncological outcome measured with ultrasensitive PSA immunoassays. In a retrospective study we analysed whether SVRP affects oncological outcome in terms of ultrasensitive PSA nadir and biochemical recurrence as compared with standard robotic assisted laparoscopic radical prostatectomy (sRALP). METHODS Overall, 102 patients underwent robotic prostatectomy. Patients were non-randomly allocated to the following surgical techniques: a SVRP group of 39 patients who underwent robotic radical prostatectomy sparing the tips of the seminal vesicles; a standard group of 63 patients who were treated with sRALP. Inclusion criteria were histologically proven negative margins (R0) and negative lymph node status (pN0). PSA was measured with an ultrasensitive assay. The Mann-Whitney U-test was used to compare the differences in PSA nadir and follow-up PSA. Biochemical recurrence was diagnosed if PSA rose to ≥0.2 mg/ml. RESULTS Median (range) follow-up was 31.4 (16.4–43.8) months. Preoperative PSA was 5.8 (0.13–15.29) ng/ml in the SVRP group and 7.1 (0.8–46) ng/ml in the sRALP group. Two cases of biochemical recurrence occurred in the sRALP group during follow-up. One of these two patients presented with locally advanced prostate carcinoma diagnosed from the definitive pathological specimen (pT3b). No patient of the SVRP group had seminal vesicle invasion or biochemical recurrence. No significant between-group difference in terms of PSA nadir and follow-up PSA was recorded. However, the percentage of patients who did not reach PSA nadir values of <0.01 ng/ml was higher in the SVRP group (10 vs 5% in the sRALP group). CONCLUSIONS Compared with sRALP, SVRP had no clinical impact on oncological outcome in terms of PSA nadir or biochemical recurrence measured with an ultrasensitive PSA immunoassay. A slightly higher PSA nadir after SVRP seems to be expected, which needs to be mentioned during follow-up of these patients.

DNA-Mediated Nanoscale Metal-Organic Frameworks for Ultrasensitive Photoelectrochemical Enzyme-Free Immunoassay.

A novel enzyme-free photoelectrochemical (PEC) immunoassay was developed for the ultrasensitive detection of prostate specific antigen (PSA) based on the DNA-mediated nanoscale zirconium-porphyrin MOFs (NMOFs). By virtue of the intrinsic coordination between unsaturated zirconium sites of the NMOFs frameworks and phosphonate groups, the 5'-phosphorylared ss-DNA-tagged antibody (Ab-DNA) conjugate with a consecutive stretch of guanines as a spacer could be loaded on the NMOFs easily, obtaining a novel type of Ab-DNA-functionalized NMOFs complex. Additionally, as a photocathode PEC active nanomaterial, NMOFs exhibited a significant enhanced photocurrent response with the presence of dopamine under oxygen-containing aqueous media at -0.3 V (vs Ag/AgCl). Furthermore, with the aid of the electrochemical grafting of polyamidoamine (PAMAM) dendrimers functionalized interface, the novel type of Ab-DNA-NMOFs further served as a PEC signal nanoprobe for the ultrasensitive PSA immunoassay. Under optimal conditions, the corresponding immunosensor possessed a wide calibration range of 1 pg mL-1 to 10 ng mL-1 and a limit of detection (LOD) of 0.2 pg mL-1. This present work demonstrated the promising application of DNA-mediated NMOFs in developing highly sensitive, environmentally friendly, and cost-effective PEC biosensors.

Immuno-Electrochemiluminescent Imaging of a Single Cell Based on Functional Nanoprobes of Heterogeneous Ru(bpy)32+@SiO2/Au Nanoparticles.

It is valuable to develop a sensing platform for not only detecting a tumor marker in body fluids but also measuring its expression at single cells. In the present study, a simple closed bipolar electrodes-based electrochemiluminescence (BPEs-ECL) imaging strategy was developed for visual immunoassay of prostate specific antigen (PSA) at single cells using functional nanoprobes of heterogeneous Ru(bpy)32+@SiO2/Au nanoparticles. Multiple-assisted ECL signal amplification strategy was introduced into the detection system on the basis of the synergetic amplifying effect of the anodic and cathodic amplification. On the basis of the synergetic amplifying effect, the detection limits of PSA by using photomultiplier tube and charge-coupled device (CCD) imaging are 3.0 and 31 pg/mL, respectively. The obtained immunosensor was employed to evaluate PSA levels in serum samples with a satisfying result. Moreover, the obtained functional nanoprobes were used to visually profile the PSA expression on the surface of single LNCaP cells (a kind of prostate cancer cells) based on a bare BPE. The results show that the functional nanoprobes-based ECL imaging immunoassay provides a promising visual platform for detecting tumor markers (proteins and cancer cells) and thus shows a high potential in cancer diagnosis.

Three-dimensional Au nanoparticles/nano-poly(3,4-ethylene dioxythiophene)- graphene aerogel nanocomposite: A high-performance electrochemical immunosensing platform for prostate specific antigen detection

Conductive poly(3,4-ethylenedioxythiophene) (PEDOT) composites have emerged as potential candidates for electrochemical biosensors, however, the sensing performance was mainly relied on their structure and composition. In this work, a novel three-dimensional (3D) structural nano-PEDOT-graphene aerogel (nano-PEDOT-GA) composite was designed via the in-situ polymerization of nano-PEDOT on porous 3D GA. SEM revealed that the introduction of GA could induce the growth of worm-like PEDOT. Subsequently, Au nanoparticles (AuNPs) were directed to nano-PEDOT-GA surface by electrodeposition method. Featuring the excellent biocompatibility, high specific surface area and good conductivity of AuNPs/nano-PEDOT-GA, a highly sensitive label-free immunosensor was developed using AuNPs/nano-PEDOT-GA as signal amplification platform for detecting prostate specific antigen (PSA). Under the optimal conditions, the fabricated immunosensor presented a good linear in the analytical range of 0.0001–50 ng mL−1 with a low detection limit of 0.03 pg mL−1 (S/N = 3), high selectivity against other serum interfering substance and good stability and reproducibility, which provides a promising platform for the clinical immunoassay of PSA.

Extraction, purification of prostate-specific antigen (PSA), and establishment of radioimmunoassay system as a diagnostic tool for prostate disorders

ABSTRACTThis study aimed to provide an easy and effective method for extraction and purification of prostate-specific antigen (PSA) from human seminal fluid with high quantity (14 mg) and high purity (98%). The obtained PSA was injected into rabbits for production of anti-PSA polyclonal antibody (titer 1/1000), labeled with radioactive iodine-125 for preparation of radioactive PSA tracer (purity 98 ± 1.8% and specific activity 64 ± 1.9 µCi/µg), and used in preparation of PSA standards. All prepared components can be used in PSA immunoassays specially radioimmunoassay (RIA) kit preparation as a diagnostic tool for prostatic diseases.