A photoelectrochemical biosensor based on methylene blue sensitized Bi5O7I for sensitive detection of PSA

Nucleic acid aptamer-based biosensors and their application in thrombin analysis

Thrombin is a multifunctional serine protease that plays an important role in coagulation and anticoagulation processes. Aptamers have been widely applied in biosensors due to their high specificity, low cost and good biocompatibility. This review summarizes recent advances in thrombin quantification using aptamer-based biosensors. The primary focus is optical sensors and electrochemical sensors, along with their applications in thrombin analysis and disease diagnosis.

2D carbon materials based photoelectrochemical biosensors for detection of cancer antigens

Cancer is a leading cause of death globally and early diagnosis is of paramount importance for identifying appropriate treatment pathways to improve cancer patient survival. However, conventional methods for cancer detection such as biopsy, CT scan, magnetic resonance imaging, endoscopy, X-ray and ultrasound are limited and not efficient for early cancer detection. Advancements in molecular technology have enabled the identification of various cancer biomarkers for diagnosis and prognosis of the deadly disease. The detection of these biomarkers can be done by biosensors. Biosensors are less time consuming compared to conventional methods and has the potential to detect cancer at an earlier stage. Compared to conventional biosensors, photoelectrochemical (PEC) biosensors have improved selectivity and sensitivity and is a suitable tool for detecting cancer agents. Recently, 2D carbon materials have gained interest as a PEC sensing platform due to their high surface area and ease of surface modifications for improved electrical transfer and attachment of biorecognition elements. This review will focus on the development of 2D carbon nanomaterials as electrode platform in PEC biosensors for the detection of cancer biomarkers. The working principles, biorecognition strategies and key parameters that influence the performance of the biosensors will be critically discussed. In addition, the potential application of PEC biosensor in clinical settings will also be explored, providing insights into the future perspective and challenges of exploiting PEC biosensors for cancer diagnosis.

In situ growth of WO3/BiVO4 nanoflowers onto cellulose fibers to construct photoelectrochemical/colorimetric lab-on-paper devices for the ultrasensitive detection of AFP

In this work, novel dual-mode lab-on-paper devices based on in situ grown WO₃/BiVO₄ heterojunctions onto cellulose fibers, as signal amplification probes, were successfully fabricated by the integration of photoelectrochemical (PEC)/colorimetric analysis technologies into a paper sensing platform for the ultrasensitive detection of alpha-fetoprotein (AFP). Specifically, to achieve an impressive PEC performance of the lab-on-paper device, the WO₃/BiVO₄ heterojunction was in situ grown onto the surface of cellulose fibers assisted with Au nanoparticle (Au NP) functionalization for enhancing the conductivity of the working zone of the device. With the target concentration increased, more immune conjugates could be captured by the proposed paper photoelectrode, which could lead to a quantitative decrease in the photocurrent intensity, eventually realizing the accurate PEC signal readout. To meet the requirement of end-user application, a colorimetric signal readout system was designed for the lab-on-paper device based on the color reaction of 3,3'5,5'-tetramethylbenzidine (TMB) oxidized by WO₃/BiVO₄ nanoflowers in the presence of H₂O₂. Noticeably, it is the first time that the WO₃/BiVO₄ heterojunction is in situ grown onto cellulose fibers, which enhances the sensitivity in view of both their PEC activity and catalytic ability. By controlling the conversion process of hydrophobicity and hydrophilicity on the lab-on-paper device combined with diverse origami methods, the dual-mode PEC/colorimetric signal output for the ultrasensitive AFP detection was realized. Under optimal conditions, the proposed dual-mode lab-on-paper device could enable the sensitive PEC/colorimetric diagnosis of AFP in the linear range of 0.09-100 ng mL^-1 and 5-100 ng mL^-1 with the limit of detection of 0.03 and 1.47 ng mL^-1, respectively.