A bimetallic nanocoral Au decorated with Pt nanoflowers (bio)sensor for H2O2 detection at low potential

Smartphone-Integrated Automated Sensor Employing Electrochemically Engineered 3D Bimetallic Nanoflowers for Hydrogen Peroxide Quantification in Milk

Hydrogen peroxide (H2O2), one of the reactive oxygen species in living beings, serves as a regulator of various cellular processes. However, excessive peroxide concentrations are linked to oxidative stress and promptly disrupt cellular components, leading to several pathological conditions in the body. Moreover, it is extremely reactive and has a limited lifetime; thus, H2O2 sensing remains a prominent focus of research. Enzymatic sensing probes were widely employed to detect H2O2 in the recent past; however, they are susceptible to intrinsic chemical and thermal instabilities, which decrease the reliability and durability of the surface. This research was designed to come up with a feasible solution to this problem. Herein, a novel nonenzymatic peroxidase-mimic three-dimensional (3D) bimetallic nanoflower has been synergistically engineered for quick sensing of H2O2. The sensor platform showed minimal resistance or enhanced charge transfer properties as well as remarkable analytical capability, having a broad linear range between 0.01 and 1 nM and a detection limit of 1.46 ± 0.07 pM. The probe responded to changes in H2O2 concentration in just 2.10 ± 0.02 s, making it a quick sensing platform for H2O2 tracking. This peroxidase-mimic nanozyme probe showed minimal sensitivity to interferants often seen in real-world sample matrices and possessed good recoveries ranging from 92.88 to 99.09% in milk samples. Further, a facile and user-friendly smartphone application (APP) named "HPeroxide-Check" was developed and integrated into the sensor to check the milk adulteration by detecting H2O2. It processes the current output obtained from the sensing interface and provides real-time peroxide concentrations in milk. The entire procedure of fabricating the probe is a single, highly robust step that takes only 10 min and is coupled with a smartphone APP, highlighting the sensor's quick manufacturing and deployment for automated H2O2 monitoring in industrial and point-of-care settings.

Recent Progress of the Practical Applications of the Platinum Nanoparticle-Based Electrochemistry Biosensors

The detection of biomolecules using various biosensors with excellent sensitivity, selectivity, stability, and reproducibility, is of great significance in the analytical and biomedical fields toward achieving their practical applications. Noble metal nanoparticles are favorable candidates due to their unique optical, surface electrical effect, and catalytic properties. Among these noble metal nanoparticles, platinum nanoparticles (Pt NPs) have been widely employed for the detection of bioactive substances such as glucose, glutamic acid, and hormones. However, there is still a long way to go before the potential challenges in the practical applications of biomolecules are fully overcome. Bearing this in mind, combined with our research experience, we summarized the recent progress of the Pt NP-based biosensors and highlighted the current problems that exist in their practical applications. The current review would provide fundamental guidance for future applications using the Pt NP-based biosensors in food, agricultural, and medical fields.

Glucose Biosensor Based on Disposable Activated Carbon Electrodes Modified with Platinum Nanoparticles Electrodeposited on Poly(Azure A)

Herein, a novel electrochemical glucose biosensor based on glucose oxidase (GOx) immobilized on a surface containing platinum nanoparticles (PtNPs) electrodeposited on poly(Azure A) (PAA) previously electropolymerized on activated screen-printed carbon electrodes (GOx-PtNPs-PAA-aSPCEs) is reported. The resulting electrochemical biosensor was validated towards glucose oxidation in real samples and further electrochemical measurement associated with the generated H₂O₂. The electrochemical biosensor showed an excellent sensitivity (42.7 μA mM⁻¹ cm⁻²), limit of detection (7.6 μM), linear range (20 μM–2.3 mM), and good selectivity towards glucose determination. Furthermore, and most importantly, the detection of glucose was performed at a low potential (0.2 V vs. Ag). The high performance of the electrochemical biosensor was explained through surface exploration using field emission SEM, XPS, and impedance measurements. The electrochemical biosensor was successfully applied to glucose quantification in several real samples (commercial juices and a plant cell culture medium), exhibiting a high accuracy when compared with a classical spectrophotometric method. This electrochemical biosensor can be easily prepared and opens up a good alternative in the development of new sensitive glucose sensors.

Biosensor Applications of Electrodeposited Nanostructures

The development of biosensors for a range of analytes from small molecules to proteins to oligonucleotides is an intensely active field. Detection methods based on electrochemistry or on localized surface plasmon responses have advanced through using nanostructured electrodes prepared by electrodeposition, which is capable of preparing a wide range of different structures. Supported nanoparticles can be prepared by electrodeposition through applying fixed potentials, cycling potentials, and fixed current methods. Nanoparticle sizes, shapes, and surface densities can be controlled, and regular structures can be prepared by electrodeposition through templates. The incorporation of multiple nanomaterials into composite films can take advantage of the superior and potentially synergistic properties of each component. Nanostructured electrodes can provide supports for enzymes, antibodies, or oligonucleotides for creating sensors against many targets in areas such as genomic analysis, the detection of protein antigens, or the detection of small molecule metabolites. Detection can also be performed using electrochemical methods, and the nanostructured electrodes can greatly enhance electrochemical responses by carefully designed schemes. Biosensors based on electrodeposited nanostructures can contribute to the advancement of many goals in bioanalytical and clinical chemistry.

Dual-type responsive electrochemical biosensor for the detection of α2,6-sialylated glycans based on AuNRs-SA coupled with c-SWCNHs/S-PtNC nanocomposites signal amplification

In this study, a dual-type responsive electrochemical biosensor was developed for the quantitative detection of α2,6-sialylated glycans (α2,6-sial-Gs), a potential biomarker of tumors. The gold nanorods (AuNRs), which exhibited great specific surface area, as well as good biocompatibility, was synthesized by the way of seed growth method. Furthermore, a biotin-streptavidin (biotin-SA) system was introduced to improve the immunoreaction efficiency. Accordingly, a label-free biosensor was fabricated based on AuNRs-SA for the quick detection of α2,6-sial-Gs by recording the signal of differential pulse voltammetry (DPV). Furthermore, to expand the ultrasensitive detection of α2,6-sial-Gs, a carboxylated single-walled carbon nanohorns/sulfur-doped platinum nanocluster (c-SWCNHs/S-PtNC) was synthesized for the first time as a novel signal label, which showed an excellent catalytic performance. The usage of c-SWCNHs/S-PtNC could significantly amplify the electrochemical signal recorded by the amperometric i-t curve. Herein, a sandwich type biosensor was constructed by combining the AuNRs-SA on the electrode and c-SWCNHs/S-PtNC (signal amplifier). The label-free biosensor possessed a linear range from 5 ng mL^-1 to 5 μg mL^-1 with a detection limit of 0.50 ng mL^-1, and the sandwich-type biosensor possessed a wide linear range from 1 fg mL^-1 to 100 ng mL^-1 with a detection limit of 0.69 fg mL^-1. Furthermore, the biosensor exhibited excellent recovery and stability, indicating its potential for use in actual samples.