Biosensing strategies for diagnosis of prostate specific antigen

Digital droplet immunoassay based on a microfluidic chip with magnetic beads for the detection of prostate-specific antigen

Sensitive biomarker detection techniques are beneficial for both disease diagnosis and postoperative examinations. In this study, we report an integrated microfluidic chip designed for the immunodetection of prostate-specific antigens (PSAs). The microfluidic chip is based on the three-dimensional structure of quartz capillaries. The outlet channel extends to 1.8 cm, effectively facilitating the generation of uniform droplets ranging in size from 3 to 50 μm. Furthermore, we successfully immobilized the captured antibodies onto the surface of magnetic beads using an activator, and we constructed an immunosandwich complex by employing biotinylated antibodies. A key feature of this microfluidic chip is its integration of microfluidic droplet technology advantages, such as high-throughput parallelism, enzymatic signal amplification, and small droplet size. This integration results in an exceptionally sensitive PSA detection capability, with the detection limit reduced to 7.00 ± 0.62 pg/mL.

Self-assembled monolayer-assisted label-free electrochemical genosensor for specific point-of-care determination of Haemophilus influenzae

For sensitive detection of the L-fuculokinase genome related to the Haemophilus influenzae (H. influenzae), this research work demonstrates the label-free electrochemical-based oligonucleotide genosensing assay relying on the performing hybridization process. To enhance the electrochemical responses, multiple electrochemical modifier-tagged agents were effectively utilized. For attaining this goal, NiCr-layered double hydroxide (NiCr LDH) has been synthesized and combined with biochar (BC) to create an efficient electrochemical signal amplifier that has been immobilized on the surface of the bare Au electrode. Low detection and quantification limits (LOD and LOQ) associated with the designed genosensing bio-platform to detect L-fuculokinase have been achieved to 6.14 fM and 11 fM, respectively. Moreover, the wide linear range of 0.1 to 1000 pM demonstrates the capability of the designed platform. Investigated were the 1-, 2-, and 3-base mismatched sequences, and the negative control samples clarified the high selectivity and better performance of the engineered assay. The values of 96.6-104% and 2.3-3.4% have been obtained for the recoveries and RSDs, respectively. Furthermore, the repeatability and reproducibility of the associated bio-assay have been studied. Consequently, the novel method is appropriate for rapidly and quantitatively detecting H. influenzae, and is considered a better candidate for advanced tests on biological samples such as urine samples.

An ultrasensitive and disposable electrochemical aptasensor for prostate-specific antigen (PSA) detection in real serum samples

In this study, we constructed a disposable indium tin oxide polyethylene terephthalate film (ITO-PET)-based electrochemical aptasensor for analyzing prostate-specific antigen (PSA), one of the most important biomarkers of prostate cancer. Because of their clinical importance, building PSA biosensing systems with high sensitivity and stability is essential. However, it still presents significant difficulties, such as low detection limits. We designed a platform to covalently bind the amino-terminated aptamer by modifying the ITO-PET surface with carboxyethylsilanetriol (CTES) to obtain a self-assembled monolayer (SAM). We also evaluated the potential for use in real human serum samples by investigating the optimal operating conditions and analytical performance characteristics of the developed biosensor. The design we present here exhibits excellent precision, with a limit of detection (LOD) as low as 8.74 fg/mL PSA. The broad linear detection range of the biosensor under optimal conditions was determined as 1.0-1500 fg/mL. The dissociation constant (K_d) for the aptamer was also calculated as 46.28 ± 5.63 nM by evaluating the impedimetric response as a function of PSA concentration. The aptasensor displayed considerable repeatability (1.3% RSD) and reproducibility (7.51% RSD) and good storage stability (98.34% of the initial activity for 8 weeks). Additionally, we demonstrated that the technique we developed was quite efficient in estimating the kinetics of aptamer-analyte interactions by determining the K_d and single-frequency impedance (SFI) data. In conclusion, we proposed a selective and sensitive biosensor with the potential for clinical application and superior performance in real serum samples.

Gold Nanoparticles-MWCNT Based Aptasensor for Early Diagnosis of Prostate Cancer

Prostate cancer is one of the most frequently diagnosed male malignancies and can be detected by prostate-specific antigen (PSA) as a biomarker. To detect PSA, several studies have proposed using antibodies, which are not economical and require a long reaction time. In this study, we propose to use self-assembled thiolated single-strand DNA on electrodes functionalized by multi-walled carbon nanotubes (MWCNT) modified with gold nanoparticles (AuNPs) to realize a low-cost label-free electrochemical biosensor. In this regard, the PSA aptamer was immobilized via electrostatic adsorption on the surface of a screen-printed MWCNT/AuNPs electrode. The immobilization process was enhanced due to the presence of Au nanoparticles on the surface of the electrode. Surface characterization of the electrode at different stages of modification was performed by electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) and contact angle for surface tension properties. The results showed an increase in surface roughness due to the absorbance of the aptamer on the electrode surfaces. The developed sensor has an extended linear range of 1-100 ng/mL, and a very low limit of detection down to 1 pg/mL. In addition, the reaction has a binding time of only five minutes on the developed electrodes. Investigations of the biosensor selectivity against several substances revealed an efficient selectivity for PSA detection. With this approach, low-cost biosensors with high sensitivity can be realized which have a wide linearity range and a low limit of detection, which are necessary for the early detection of prostate cancer.

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.

Disposal Immunosensor for Sensitive Electrochemical Detection of Prostate-Specific Antigen Based on Amino-Rich Nanochannels Array-Modified Patterned Indium Tin Oxide Electrode

Sensitive detection of prostate-specific antigens (PSA) in serum is essential for the prevention and early treatment of prostate cancer. Simple and disposable electrochemical immunosensors are highly desirable for screening and mobile detection of PSAs in high-risk populations. Here, an electrochemical immunosensor was constructed based on amino-rich nanochannels array-modified patterned, inexpensive, and disposable indium tin oxide (ITO) electrodes, which can be employed for the sensitive detection of PSA. Using an amino-group-containing precursor, a vertically ordered mesoporous silica nanochannel film (VMSF) containing amino groups (NH₂-VMSF) was rapidly grown on ITO. When NH₂-VMSF contained template surfactant micelle (SM), the outer surface of NH₂-VMSF was directionally modified by aldehyde groups, which enabled further covalent immobilization of the recognitive antibody to prepare the immuno-recognitive interface. Owing to the charge-based selective permeability, NH₂-VMSF can electrostatically adsorb negatively charged redox probes in solution (Fe(CN)₆^3-/4-). The electrochemical detection of PSA is realized based on the mechanism that the antigen-antibody complex can reduce the diffusion of redox probes in solution to the underlying electrode, leading to the decrease in electrochemical signal. The constructed immunosensor can achieve sensitive detection of PSA in the range from 10 pg/mL to 1 μg/mL with a limit of detection (LOD) of 8.1 pg/mL. Sensitive detection of PSA in human serum was also achieved. The proposed disposable immunosensor based on cheap electrode and nanochannel array is expected to provide a new idea for developing a universal immunosensing platform for sensitive detection of tumor markers.

The Expression of miR-205 in Prostate Carcinoma and the Relationship with Prognosis in Patients

Purpose. We aimed to investigate the changes of serum and cell exosome miR-205 levels in patients with prostate carcinoma and its clinical significance. Materials and Methods. Firstly, pronouncement of miR-205 in normal and prostate carcinoma tissues was analyzed by using UALCAN database. The relationship between miR-205 in tumor tissues and the pathological and clinical characteristics of patients with prostate carcinoma were analyzed. Consequently, 60 people with prostate carcinoma were collected to the Minhang Hospital from August 2016 to August 2021. Serum of patients in the two groups was collected, and RNA in serum exosomes was extracted, and qRT-PCR was used to analyze the expression of miR-205 mediated by serum exosomes. Meanwhile, the relationship among the clinical as well as pathological aspects and bodement of patients with prostate carcinoma and the pronouncement level of miR-205 mediated by exosome was compared. Next, assays like wound healing and CKK-8 were used to investigate the effects of miR-205 in exosomes extracted from prostate carcinoma on the augmentation and metastasis of prostate carcinoma. Results. The results showed that the pronouncement level of miR-205 in tissues with prostate carcinoma was significantly lower than that in normal prostate tissues. In addition, the pronouncement level of miR-205 in fluid exosome of people with prostate carcinoma and exosomes derived from the lines of prostate carcinoma was considerably less than that in serum exosomes of healthy patients and that of normal cell lines of prostate. The pronouncement level of miR-205 in fluid exosomes of people with prostate carcinoma was negatively associated with cancer phase, uncontrolled cell division in lymph nodes, distant metastasis, and PSA level at initial diagnosis. Analysis (multivariate and univariate) showed that miR-205 pronouncement was a sovereign threat cause for prognosis of prostate cancer patients. Additionally, the pronouncement and metastasis of prostate carcinoma can be restricted by the overexpression of miR-205. Conclusion. The pronouncement of miR-205 in liquid derived exosomes is correlated with the prediction of people with prostate carcinoma and may be a new marker for identification and cure of prostate carcinoma.

Fluorescent Immunoassay with a Copper Polymer as the Signal Label for Catalytic Oxidation of O-Phenylenediamine

This work suggested that Cu2+ ion coordinated by the peptide with a histidine (His or H) residue in the first position from the free N-terminal reveals oxidase-mimicking activity. A biotinylated polymer was prepared by modifying His residues on the side chain amino groups of lysine residues (denoted as KH) to chelate multiple Cu2+ ions. The resulting biotin-poly-(KH-Cu)20 polymer with multiple catalytic sites was employed as the signal label for immunoassay. Prostate specific antigen (PSA) was determined as the model target. The captured biotin-poly-(KH-Cu)20 polymer could catalyze the oxidation of o-phenylenediamine (OPD) to produce fluorescent 2,3-diaminophenazine (OPDox). The signal was proportional to PSA concentration from 0.01 to 2 ng/mL, and the detection limit was found to be eight pg/mL. The high sensitivity of the method enabled the assays of PSA in real serum samples. The work should be valuable for the design of novel biosensors for clinical diagnosis.

DNA walker-amplified signal-on electrochemical aptasensors for prostate-specific antigen coupling with two hairpin DNA probe-based hybridization reaction

Electrochemical aptasensing systems have been developed for screening low-abundance disease-related proteins, but most of them involve multiple washings and multi-step separation during measurements, and thus are disadvantageous for routine use. In this work, an innovative and simple electrochemical aptasensing platform was designed for the voltammetric detection of prostate-specific antigen (PSA) in biological fluids without any washing and separation steps. This system mainly included a PSA-specific aptamer, a DNA walker and two hairpin DNA probes (i.e., thiolated hairpin DNA1 and ferrocene-labeled hairpin DNA2). Introduction of target PSA caused the release of the DNA walker from a partially complementary aptamer/DNA walker hybridization strand. The dissociated DNA walker opened the immobilized hairpin DNA1 on the electrode, accompanying subsequent displacement reaction with hairpin DNA2, thus resulting in the DNA walker step-by-step reaction with numerous hairpin DNA1 probes on the sensing interface. In this case, numerous ferrocene molecules were close to the electrode to amplify the voltammetric signal within the applied potentials. All reactions and electrochemical measurements including the target/aptamer reaction and hybridization chain reaction were implemented in the same detection cell. Under optimal conditions, the fabricated electrochemical aptasensor gave good voltammetric responses relative to the PSA concentrations within the range of 0.001-10 ng mL^-1 at an ultralow detection limit of 0.67 pg mL^-1. A good reproducibility with batch-to-batch errors was acquired for target PSA down to 11.5%. Non-target analytes did not interfere with the voltammetric signals of the electrochemical aptasensors. Meanwhile, 15 human serum specimens were measured with electrochemical aptasensors, and displayed well-matched results in comparison with the referenced human PSA enzyme-linked immunosorbant assay (ELISA) method. Significantly, this method provides a new horizon for the quantitative monitoring of low-concentration biomarkers or nucleic acids.

Comprehensive Landscape of HOXA2, HOXA9, and HOXA10 as Potential Biomarkers for Predicting Progression and Prognosis in Prostate Cancer

Prostate cancer (PCa) is recognized as a common malignancy in male patients. The homeobox A cluster (HOXA) family members have been confirmed to be implicated in the development of several types of tumors. However, the expression pattern and prognostic values of HOXA genes in PCa have not been investigated. In this study, we analyzed TCGA datasets and identified six HOXA family members which showed a dysregulated expression in PCa specimens compared with nontumor specimens. We also explored the potential mechanisms involved in the dysregulation of HOXA family members in PCa, and the results of Pearson's correlation revealed that most HOXA members were negatively related to the methylation degree. Moreover, we explored the prognostic values of HOXA family members and identified six survival-related HOXA members. Importantly, HOXA2, HOXA9, and HOXA10 were identified as critical PCa-related genes which were abnormally expressed in PCa and associated with clinical outcomes of PCa patients. Then, we explored the association between the above three genes and immune cell infiltration. We observed that the levels of HOXA2, HOXA9, and HOXA10 were associated with the levels of immune infiltration of several kinds of immune cells. Overall, our findings identified the potential values of the HOXA family for outcome prediction in PCa, which might facilitate personalized counselling and treatment in PCa.