Rapid and sensitive detection of prostate-specific antigen via label-free frequency shift Raman of sensing graphene

Controlled silver electrodeposition on gold nanoparticle antibody tags for ultrasensitive prostate specific antigen sensing using electrochemical and optical smartphone detection

One of the current challenges in medicine is to achieve a rapid and unequivocal detection and quantification of extremely low levels of disease biomarkers in complex biological samples. Here, we present the development and analytical evaluation of a low-cost smartphone-based system designed for ultrasensitive detection of the prostate-specific antigen (PSA) using two detection alternatives: electrochemical or optical, by coupling the smartphone with a portable potentiostat or magnifying lenses. An antibody tagged with gold nanoparticles (AuNPs), and indium tin oxide coated polyethylene terephthalate platform (ITO-PET) have been used to develop a sandwich-type immunoassay. Then, a controlled silver electrodeposition on the AuNPs surface is carried out, enhancing their size greatly. Due to such strong nanoparticle-size amplification (from nm to μm), the final detection can be dual, by measuring current intensity or the number of silver-enlarged microstructures generated. The proposed strategies exhibited limit detections (LOD) of 102 and 37 fg/mL for electrochemical and optical detection respectively. The developed immunosensor reaches excellent selectivity and performance characteristics to quantify biomarkers at clinically relevant values without any pretreatment. These proposed procedures could be useful to check and verify possible recurrence after clinical treatment of tumors or even report levels of disease serum biomarkers in early stages.

A colorimetric/electrochemical microfluidic biosensor using target-triggered DNA hydrogels for organophosphorus detection

Organophosphorus compounds are widely distributed and highly toxic to the environment and living organisms. The current detection of organophosphorus compounds is based on a single-mode method, which makes it challenging to achieve good portability, accuracy, and sensitivity simultaneously. This study designed a multifunctional microfluidic chip to develop a dual-mode biosensor employing a DNA hydrogel as a carrier and aptamers as recognition probes for the colorimetric/electrochemical detection of malathion, an organophosphorus compound. The biosensor balanced portability and stability by combining a microfluidic chip and target-triggered DNA hydrogel-sensing technologies. Moreover, the biosensor based on target-triggered DNA hydrogel modified microfluidic developed in this study exhibited a dual-mode response to malathion, providing both colorimetric and electrochemical signals. The colorimetric mode enables rapid visualization and qualitative detection and, when combined with a smartphone, allows on-site quantitative analysis with a detection limit of 56 nM. The electrochemical mode offers a broad linear range (0.01-3000 μM) and high sensitivity (a limit of detection of 5 nM). The two modes could validate each other and improve the accuracy of detection. The colorimetric/electrochemical dual-mode biosensor based on target-triggered DNA hydrogel modified microfluidic chip offers a portable, simple, accurate, and sensitive strategy for detecting harmful environmental and food substances.

Electrochemical immunosensing of tumor markers

The rising incidence and mortality rates of cancer have led to a growing need for precise and prompt early diagnostic approaches to effectively combat this disease. However, traditional methods employed for detecting tumor cells, such as histopathological and immunological techniques, are often associated with complex procedures, high analytical expenses, elevated false positive rates, and a dependence on experienced personnel. Tracking tumor markers is recognized as one of the most effective approaches for early detection and prognosis of cancer. While onco-biomarkers can also be produced in normal circumstances, their concentration is significantly elevated when tumors are present. By monitoring the levels of these markers, healthcare professionals can obtain valuable insights into the presence, progression, and response to treatment of cancer, aiding in timely diagnosis and effective management. This review aims to provide researchers with a comprehensive overview of the recent advancements in tumor markers using electrochemical immunosensors. By highlighting the latest developments in this field, researchers can gain a general understanding of the progress made in the utilization of electrochemical immunosensors for detecting tumor markers. Furthermore, this review also discusses the current limitations associated with electrochemical immunosensors and offers insights into paving the way for further improvements and advancements in this area of research.

SERS-electrochemical dual-mode detection of microRNA on same interface assisted by exonuclease III signal transformation

Dual-mode sensing has attracted more attentions which provide more accurate and reliable approach of cancer-related biomarkers. Herein, we developed a novel SERS/electrochemical dual-mode biosensor for miRNA 21 detection based on Exo III-assisted signal transformation. Firstly, the Au NPs were deposited on electrode as SERS substrate and Mn3O4/S4(DNA signal strand) was modified on Au NPs/S5 by the DNA strands S5-S4 pairing principle as hydrogen peroxide catalyst, leading to an obviously high DPV electrical signal without Raman signal. Subsequently, the presence of miRNA 21 will activate the Mn3O4/S4 to be decomposed under exonuclease III-assisted process, then the S3' chains modified with Raman molecular Cy3(Cy3-S3') is continuously connected to the Au NPs/S5 by DNA stands S5-S3' pairing principle, leading to the Raman signal response and DPV signal reduction. The biosensor shows good linear calibration curves of both SERS and electrochemical sensing modes with the detection limit of 3.98 × 10-3 nM and 6.89 × 10-5 nM, respectively. This work finds an ingenious mode for dual detection of microRNA on a same interface, which opens a new strategy for SERS and electrochemical analysis.

Fluorescence self-assembled DNA hydrogel for the determination of prostate specific antigen by aggregation induced emission

In this study, an aptamer-based, functionalized-DNA hydrogel system is developed for prostate-specific antigen (PSA) detection. A pure DNA hydrogel is constructed using specific DNA building blocks and an aptamer as a cross-linker. Firstly, silver nanoclusters (AgNCs) are constructed on the Y-shaped DNA (Y-DNA) building blocks. Then, the DNA hydrogel was formed via the addition of the cross-linker to the Y-DNA solution. In this case, the fluorescence emission of silver nanoclusters that have accumulated in the hydrogel increases due to aggregation-induced emission (AIE). The presence of PSA and its subsequent interaction with its specific aptamer dissolve the hydrogel structures, which leads to a low emission intensity. A great linear relationship was attained in this assay in the range of 0.05 to 8 ng mL-1 with a detection limit of 4.4 pg mL-1 for the detection of PSA. Additionally, the proposed aptasensor was successfully used to detect PSA in human serum samples. The recovery for different concentrations of PSA was in the range of 96.1% to 99.3%, and the RSD range was from 2.3% to 4.5%. Comparing our method to current ones in the field of PSA detection proves that our platform benefits from a simpler procedure, lower cost, and better efficiency, providing high potential for future clinical applications.

The development of a fluorescence/colorimetric biosensor based on the cleavage activity of CRISPR-Cas12a for the detection of non-nucleic acid targets

Nano-biosensors are of great significance for the analysis and detection of important biological targets. Surprisingly, the CRISPR-Cas12a system not only provides us with excellent gene editing capabilities, it also plays an important role in biosensing due to its high base resolution and high levels of sensitivity. However, most CRISPR-Cas12a-based sensors are limited by their recognition and output modes, are therefore only utilized for the detection of nucleic acids using fluorescence as an output signal. In the present study, we further explored the potential application of CRISPR-Cas12a and developed a CRISPR-Cas12a-based fluorescence/colorimetric biosensor (UCNPs-Cas12a/hydrogel-MOF-Cas12a) that provides an efficient targeting system for small molecules and protein targets. These two sensors yield multiple types of signal outputs by converting the target molecule into a deoxyribonucleic acid (DNA) signal input system using aptamers, amplifying the DNA signal by catalyzed hairpin assembly (CHA), and then combining CRISPR-Cas12a with various nanomaterials. UCNPs-Cas12a/hydrogel-MOF-Cas12a exhibited prominent sensitivity and stability for the detection of estradiol (E2) and prostate-specific antigen (PSA), and was successfully applied for the detection of these targets in milk and serum samples. A major advantage of the hydrogel-MOF-Cas12a system is that the signal output can be observed directly. When combined with aptamers and nanomaterials, CRISPR-Cas12a can be used to target multiple targets, with a diverse array of signal outputs. Our findings create a foundation for the development of CRISPR-Cas12a-based technologies for application in the fields of food safety, environmental monitoring, and clinical diagnosis.

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.

Carbon-based biosensors from graphene family to carbon dots: A viewpoint in cancer detection

According to the latest report by International Agency for Research on Cancer, 19.3 million new cancer cases and 10 million cancer deaths were globally reported in 2020. Early diagnosis can reduce these numbers significantly, and biosensors have appeared to be a solution to this problem as, unlike the traditional methods, they have low cost, rapid process, and do not need experts present on site for use. These devices have been incorporated to detect many cancer biomarkers and measure cancer drug delivery. To design these biosensors, a researcher must know about their different types, properties of nanomaterials, and cancer biomarkers. Among all types of biosensors, electrochemical and optical biosensors are the most sensitive and promising sensors for detecting complicated diseases like cancer. The carbon-based nanomaterial family has attracted lots of attention due to their low cost, easy preparation, biocompatibility, and significant electrochemical and optical properties. In this review, we have discussed the application of graphene and its derivatives, carbon nanotubes (CNTs), carbon dots (CDs), and fullerene (C60), for designing different electrochemical and optical cancer-detecting biosensors. Furthermore, the application of these carbon-based biosensors for detecting seven widely studied cancer biomarkers (HER2, CEA, CA125, VEGF, PSA, Alpha-fetoprotein, and miRNA21) is reviewed. Finally, various fabricated carbon-based biosensors for detecting cancer biomarkers and anticancer drugs are comprehensively summarized as well.

A novel ultrasensitive and fast aptamer biosensor of SEB based on AuNPs-assisted metal-enhanced fluorescence

A fluorescent biosensor strategy was developed in combination with immunomagnetic separation for rapid and sensitive detection of staphylococcal enterotoxin B (SEB). Magnetic nanoparticles (MNPs) modified with aptamer of SEB could capture the SEB. Then the gold nanoparticles (AuNPs) fluorescent probe was added and a "sandwich structure" was formed between AuNPs, SEB and MNPs. The MNPs-SEB-AuNPs structure could be separated with an additional magnetic field, which resulted the lower signals of AuNPs fluorescent probe. In optimal conditions, the current method displayed a broad quantitative range from 100 to 10⁷ fg/mL and the limit of detection was 3.43 fg/mL. The recovery of SEB-spiked milk samples ranged from 92.00 to 119.00 %, which revealed that the developed method had great accuracy. Furthermore, the method was fast and economical for ultrasensitive detection. Therefore, the fluorescent biosensor based on MNPs-AuNPs is promising for the detection of other environmental and food pollutants.

Prospects of microbial-engineering for the production of graphene and its derivatives: Application to design nanosystms for cancer theranostics

Cancer is known as one of the leading causes of morbidity and fatality, currently faced by our society. The prevalence of cancer related dieses is rapidly increasing around the world. To reduce the mortality rates, early diagnosis and subsequent treatment of cancer in timely manner is quite essential. Advancements have been made to achieve effective theranostics strategies to tackle cancerous dieses, yet very challenging to overcome this issue. Recently, advances made in the field of nanotechnology have shown tremendous potential for cancer theranostics. Different types of nanomaterials have been successfully employed to develop sophisticated diagnosis and therapy techniques. In this context, graphene and its derivatives e.g. graphene oxide (GO) and reduced graphene oxide (RGO) have been investigated as promising candidates to design graphene-based nanosystems for the diagnosis and therapeutic purpose. Further, to synthesize graphene and its derivatives different types of physicochemical methods are being adopted. However, each method has its own advantage and disadvantages. In this reference, among diverse biological methods, microbial technique can be one of the most promising and eco-friendly approach for the preparation of graphene and its derivatives, particularly GO and RGO. In this review, we summarize studies performed on the preparation of graphene and its derivatives following microbial routes meanwhile focus has been made on the preparation method and the possible mechanism involved therein. Thereafter, we have discussed applications of graphene and its derivatives to developed advanced nanosystem that can be imperative for the cancer theranostics. Results of recent studies exploring applications graphene based nanosystem for the preparation of different types of biosensors for early diagnosis; advanced therapeutic approaches by designing drug delivery nanosystems along with multifunctionality (e.g cancer imaging, drug delivery, photodynamic and photo thermal therapy) in cancer theranostics have been discussed. Particularly, emphasis has been given on the preparation techniques of graphene based nanosystems, being employed in designing of biosensing platforms, drug delivery and multifunctional nanosystems. Moreover, issues have been discussed on the preparation of graphene and its derivatives following microbial technique and the implementation of graphene based nanosystems in cancer theranostics.

Application of Internet of Things Combined with Wireless Network Technology in Volleyball Teaching and Training

Motion information collection technology is a means for measuring, tracking, and recording the movement traces of individuals in space. This method can complete the data collection of volleyball players and the ball trajectory and realize quantification and statistical analysis of the data to present a virtual model of the player's movement trajectory. It is inseparable from the acquisition of information to complete the information collection. Therefore, this work uses the radio frequency identification (RFID) technology in the Internet of Things technology to build an information collection system and apply it to volleyball sports. The existing positioning system based on RFID has problems such as significant positioning errors and high system costs due to the arrangement of a large number of readers. This paper first introduces the theoretical knowledge of the RFID system, wireless network positioning technology, and RFID system positioning method in the Internet of Things. Besides, the theoretical framework of the volleyball movement information acquisition system is presented based on the Received Signal Strength Indication of the RFID system and Location Identification based on the Dynamic Active RFID Calibration (LANDMARC) algorithm. Then, the LANDMARC algorithm is improved through the Centroid Positioning algorithm, forming the CP-LANDMARC algorithm. Finally, a simulation experiment is conducted to test the system effect. The results demonstrate that: (1) the average error of the basic LANDMARC algorithm is 0.55 meters, and the average error of the CP-LANDMARC algorithm is 0.46 meters; (2) the average error of the CP-LANDMARC algorithm is 0.43 meters when the reference label is set to be evenly distributed in a square, and the average error of the optimized algorithm is 0.38 m when the reference label is set as an equilateral triangle; and (3) when the number of reference labels increases to 110, the average error decreases from 0.38 to 0.29. This paper aims to improve the quality of volleyball teaching and training by designing a relevant sports information acquisition system.

A facile dual-mode aptasensor based on AuNPs@MIL-101 nanohybrids for ultrasensitive fluorescence and surface-enhanced Raman spectroscopy detection of tetrodotoxin

The development of ultrasensitive, reliable, and facile detection technologies for trace tetrodotoxin (TTX) is challenging. We presented a facile dual-mode aptamer-based biosensor (aptasensor) for ultrasensitive fluorescence and surface-enhanced Raman spectroscopy (SERS) detection of TTX by using gold nanoparticles (AuNPs)-embedded metal-organic framework (MOF) nanohybrids (AuNPs@MIL-101) because of their superior properties. A TTX-specific aptamer labelled with fluorescence and Raman reporter cyanine-3 (Cy3-aptamer) was selected as the recognition element and signal probe. Without immobilisation processing steps, Cy3-aptamers were effectively adsorbed onto the surface of AuNPs@MIL-101, thereby generating both fluorescence quenching and SERS enhancement. The preferential binding of TTX towards the Cy3-aptamer triggered the release of rigid Cy3-aptamer-TTX complexes from the AuNPs@MIL-101 surface, which resulted in recovered fluorescence signals and weakened SERS signals. Switched fluorescence and SERS intensities exhibited excellent linear relationships with logarithms of TTX concentrations of 0.01-300 ng/mL, and ultrahigh detection sensitivities of 6 and 8 pg/mL, respectively, were obtained. Furthermore, two quantitative detection approaches for TTX-spiked puffer fish and clam samples obtained satisfactory spiked recoveries and coefficient of variation (CV) values. Notably, the dual-mode aptasensor also successfully determined natural TTX-contaminated samples, showing excellent practical applications. The results indicated that this dual-mode measurement not only was ultrasensitive and simple but also markedly boosted analysis reliability and precision. This study is the first to propose a dual-mechanism AuNPs@MIL-101-based aptasensor for detection of trace TTX and provides a favourable pathway for developing multimode sensing platforms for various applications.

Biocompatible Osmium Telluride-Polypyrrole Nanocomposite Material: Application in Prostate Specific Antigen Immunosensing

Prostate cancer is a dominant global threat to society. It affects nearly 4000 men in South Africa annually, making it the second most threatening cancerous disease after lung cancer. A potential serological biomarker to monitor early diagnosis of prostate cancer is prostate specific antigen (PSA). We used the PSA biomarker in our work to develop an extremely sensitive electrochemical immunosensor to achieve low detection limits. The fabrication steps followed with the combination of thioglycolic acid capped osmium telluride quantum dots (TGA-OsTe2QD)-polypyrrole (PPy) nanocomposite and prostate specific antigen modified on a glassy carbon electrode. The UV-Vis signatures of TGA-OsTe2QD-PPy showed an absorption band at 262 nm which is attributed to the PPy and TGA-OsTe2QD composite. This band corresponds to the energy band gap of 4.4 and 5.4 eV. The CV responses of BSA|Ab|TGA-OsTe2QD|PPy|GCE modified electrode to prostate specific antigen (PSA) was studied within a range of 0–16 ng/mL PSA that was linear, herein referred to as liner range (LR), which produced a limit of detection (LOD) value of 0.36 ng/mL PSA. The values of the immunosensor’s calibration parameters (LR and LOD) make them suitable for real sample application, due to their coverage of the PSA concentration range (0–14 ng/mL) that is of clinical importance.

Sensitive and selective "signal-off" electrochemiluminescence sensing of prostate-specific antigen based on an aptamer and molecularly imprinted polymer

Specific and sensitive determination of prostate-specific antigen (PSA) in complex real samples holds significant importance as it is an effective molecular biomarker for the clinical diagnosis of prostate cancer. Herein, we constructed a dual-recognition electrochemiluminescence (ECL) sensor based on both the recognition elements of an aptamer and molecularly imprinted polymers (MIP) for the selective and ultrasensitive determination of PSA. The aptamer was self-assembled on gold nanoparticle (AuNP) modified electrodes through Au-S bonds. Subsequently, a layer of MIP membrane was synthesized by electropolymerization of dopamine (DA) to fabricate an aptamer-MIP sensor. After the rebinding of PSA onto imprinted cavities, the ECL response of luminol in the solution decreased. This "signal-off" strategy was employed for PSA detection with a wide linear range and a low limit of detection of 5 pg mL^-1-50 ng mL^-1 and 3.0 pg mL^-1, respectively. Compared with individual aptamer sensors, the dual-recognition sensor showed higher specific recognition ability for the determination of PSA. Meanwhile, the good stability, reproducibility, and regenerability endowed the dual recognition sensor with favorable application value in early clinical diagnosis.

A target-triggered and self-calibration aptasensor based on SERS for precise detection of a prostate cancer biomarker in human blood

Sensitive and precise detection of prostate-specific antigen (PSA) is critical for prostate cancer screening and monitoring. Herein, a target-triggered and self-calibration aptasensor based on a core-satellite nanostructure using surface-enhanced Raman spectroscopy (SERS) technology was developed for the sensitive and reliable determination of PSA protein, with a limit of detection of 0.38 ag mL-1 and a dynamic detection range of 10-2 to 10-15 mg mL-1. Furthermore, the proposed approach for the detection of PSA in patient blood samples was performed, and results showed that it is capable of providing comparable detection accuracy associated with a larger dynamic detection range and a lower detection limit as well as less sample requirement (only 5 μL) in comparison with the clinical commonly used method. Therefore, this SERS-based aptasensor for the detection of PSA in human blood samples has promising potential to be an alternative tool for clinical application in the accurate screening of prostate cancer.

Biomarkers Determination Based on Surface-Enhanced Raman Scattering

An overview of noteworthy new methods of biomarker determination based on surface-enhanced Raman scattering (SERS) is presented. Biomarkers can be used to identify the occurrence and development of diseases, which furthers the understanding of biological processes in the body. Accurate detection of a disease-specific biomarker is helpful for the identification, early diagnosis and prevention of a disease and for monitoring during treatment. The search for and discovery of valuable biomarkers have become important research hotspots. Different diseases have different biomarkers, some of which are involved in metabolic processes. Therefore, the fingerprint characteristics and band intensities in SERS spectra have been used to identify metabolites and analyze markers. As a promising technique, SERS has been widely used for the quantitative and qualitative determination of different types of biomarkers for different diseases. SERS techniques provide new technologies for the diagnosis of disease-related markers and determining the basis for clinical treatment. Herein, several SERS-based methods with excellent sensitivity and selectivity for the determination of biomarkers for tumors, viruses, Alzheimer’s disease, cardiac muscle tissue injury, and cell activity are highlighted.