High-performance amperometric biosensors and biofuel cell based on chitosan-strengthened cast thin films of chemically synthesized catecholamine polymers with glucose oxidase effectively entrapped

Current advancements and prospects of enzymatic and non-enzymatic electrochemical glucose sensors

This review discusses the most current developments and future perspectives in enzymatic and non-enzymatic glucose sensors, which have notably evolved over the preceding quadrennial period. Furthermore, a thorough exploration encompassed the sensor's intricate fabrication processes, the diverse range of materials employed, the underlying principles of detection, and an in-depth assessment of the sensors' efficacy in detecting glucose levels within essential bodily fluids such as human blood serums, urine, saliva, and interstitial fluids. It is worth noting that the accurate quantification of glucose concentrations within human blood has been effectively achieved by utilizing classical enzymatic sensors harmoniously integrated with optical and electrochemical transduction mechanisms. Monitoring glucose levels in various mediums has attracted exceptional attention from industrial to academic researchers for diabetes management, food quality control, clinical medicine, and bioprocess inspection. There has been an enormous demand for the creation of novel glucose sensors over the past ten years. Research has primarily concentrated on succeeding biocompatible and enhanced sensing abilities related to the present technologies, offering innovative avenues for more effective glucose sensors. Recent developments in wearable optical and electrochemical sensors with low cost, high stability, point-of-care testing, and online tracking of glucose concentration levels in biological fluids can aid in managing and controlling diabetes globally. New nanomaterials and biomolecules that can be used in electrochemical sensor systems to identify glucose concentration levels are developed thanks to advances in nanoscience and nanotechnology. Both enzymatic and non-enzymatic glucose electrochemical sensors have garnered much interest recently and have made significant strides in detecting glucose levels. In this review, we summarise several categories of non-enzymatic glucose sensor materials, including composites, non-precious transition metals and their metal oxides, hydroxides, precious metals and their alloys, carbon-based materials, conducting polymers, metal-organic framework (MOF)-based electrocatalysts, and wearable device-based glucose sensors deeply.

Experimental Methods to Get Polydopamine Films: A Comparative Review on the Synthesis Methods, the Films' Composition and Properties

In 2007, polydopamine (PDA) films were shown to be formed spontaneously on the surface of all known classes of materials by simply dipping those substrates in an aerated dopamine solution at pH = 8.5 in the presence of Tris(hydroxymethyl) amino methane buffer. This universal deposition method has raised a burst of interest in surface science, owing not only to the universality of this water based one pot deposition method but also to the ease of secondary modifications. Since then, PDA films and particles are shown to have applications in energy conversion, water remediation systems, and last but not least in bioscience. The deposition of PDA films from aerated dopamine solutions is however a slow and inefficient process at ambient temperature with most of the formed material being lost as a precipitate. This incited to explore the possibility to get PDA and related films based on other catecholamines, using other oxidants than dissolved oxygen and other deposition methods. Those alternatives to get PDA and related films are reviewed and compared in this paper. It will appear that many more investigations are required to get better insights in the relationships between the preparation method of PDA and the properties of the obtained coatings.

Preparation of novel HKUST-1-glucose oxidase composites and their application in biosensing

Copper-based metal-organic frameworks (MOF) and multi-walled carbon nanotubes (HKUST-1-MWCNTs) composite were synthesized by one-step hydrothermal method, and PDA-enzyme-HKUST-1-MWCNTs composite was prepared by one-pot method for the construction of glucose biosensors, which realized the sensitive amperometric detection of glucose at 0.7 V (vs. SCE). The sensitivity of the sensor for glucose detection was 178 μA mM^-1cm^-2 in the wide linear range of 0.005 ~ 7.05 mM, the detection limit was 0.12 μM and the corresponding RSD was 3.8%. Its high performance is mainly benefitted from the high porosity and large specific surface area of HKUST-1, the good conductivity of MWCNTs, and the excellent adhesion and dispersion of PDA. The strategy of combining PDA and MWCNTs to improve the dispersion and conductivity of MOF is expected to achieve a wider application of MOF-based materials in the electrochemical biosensing field.

Advancement in Nanoformulations for the Management of Diabetic Wound Healing

People with diabetes have a very slow tendency for wound healing. Wound healing is a vast process where several factors inhibit the sequence of healing. Nano formulation plays a major role during acute and chronic wound healing. The present manuscript aims to discuss the role of nanoformulation in the treatment of diabetic wound healing. Diabetes is a common disease that has harmful consequences which lead to bad health. During the literature survey, it was observed that nanotechnology has significant advantages in the treatment of diabetic wound healing. The present manuscript summarized the role of nanomaterials in wound healing, challenges in diabetic wound healing, physiology of wound healing, a limitation that comes during wound repair, and treatments available for wound healing. After a comprehensive literature survey, it can be concluded that health worker needs more focus on the area of wound healing in diabetic patients. Medical practitioners, pharmaceutical and biomedical researchers need more attention towards the utilization of nanoformulations for the treatment of wound healing, specifically in the case of diabetes.

Nanoparticle-Based Electrodes with High Charge Transfer Efficiency through Ligand Exchange Layer-by-Layer Assembly

Organic-ligand-based solution processes of metal and transition metal oxide (TMO) nanoparticles (NPs) have been widely studied for the preparation of electrode materials with desired electrical and electrochemical properties for various energy devices. However, the ligands adsorbed on NPs have a significant effect on the intrinsic properties of materials, thus influencing the performance of bulk electrodes assembled by NPs for energy devices. To resolve these critical drawbacks, numerous approaches have focused on developing unique surface chemistry that can exchange bulky ligands with small ligands or remove bulky ligands from NPs after NP deposition. In particular, recent studies have reported that the ligand-exchange-induced layer-by-layer (LE-LbL) assembly of NPs enables controlled assembly of NPs with the desired interparticle distance, and interfaces, dramatically improving the electrical/electrochemical performance of electrodes. This emerging approach also demonstrates that efficient surface ligand engineering can exploit the unique electrochemical properties of individual NPs and maximize the electrochemical performance of the resultant NP-assembled electrodes through improved charge transfer efficiency. This report focuses on how LE-LbL assembly can be effectively applied to NP-based energy storage/conversion electrodes. First, the basic principles of the LE-LbL approach are introduced and then recent progress on NP-based energy electrodes prepared via the LE-LbL approach is reviewed.

Rational design of electroactive redox enzyme nanocapsules for high-performance biosensors and enzymatic biofuel cell

The potential application of biodevices based on enzymatic bioelectrocatalysis are limited by poor stability and electrochemical performance. To solve the limitation, modifying enzyme with functional polymer to tailor enzyme function is highly desirable. Herein, glucose oxidase (GOx) was chosen as a model enzyme, and according to the chemical structure of GOx cofactor (flavin adenine dinucleotide, FAD), we customize a biomimetic cofactor containing vinyl group (SFAD) for GOx, and prepared an GOx nanocapsule via in-situ polymerization. The characterization of particle size distribution, TEM, fluorescence and electrochemical performance indicated the successful formation of electroactive GOx nanocapsule with SFAD-containing polymeric network (n (GOx-SFAD-PAM)). The network can act as an electronic "highway" to link the active site with electrode, with capability to accelerate electron transfer as well as enhanced GOx stability. Further investigation of bioelectrocatalysis shows that n (GOx-SFAD-PAM)-based biosensor has low detection potential (-0.4 vs. Ag/AgCl), high sensitivity (64.97 μAmM^-1cm^-2), good anti-interference performance, quick response (3⁓5s) and excellent stability, and that n (GOx-SFAD-PAM)-based enzymatic biofuel cell (EBFC) has the high maximum power density (1011.21 μWcm^-2), which is a 385-fold increase over that of native GOx-based EBFC (2.62 μWcm^-2). This study suggests that novel enzyme nanocapsule with electroactive polymeric shell might provide a prospective solution for the performance improvement of enzymatic bioelectrocatalysis-based biodevices.

Microwave-Accelerated Rapid, Chemical Oxidant-Free, Material-Independent Surface Chemistry of Poly(dopamine)

A simple strategy for the rapid preparation of multifunctional polydopamine (pDA) coatings is demonstrated. Microwave irradiation of the coating solution enables the formation of a ≈18 nm thick, genuine pDA coating in 15 min, which is ≈18 times faster than conventional coating. The acceleration effect results from the radical generation and temperature increase, which facilitate thermally accelerated radical polymerization of dopamine.

Enzymatic Biofuel Cells on Porous Nanostructures

Biofuel cells (BFCs) that utilize enzymes as catalysts represent a new sustainable and renewable energy technology. Numerous efforts have been directed to improve the performance of the enzymatic BFCs (EBFCs) with respect to power output and operational stability for further applications in portable power sources, self-powered electrochemical sensing, implantable medical devices, etc. The latest advances in EBFCs based on porous nanoarchitectures over the past 5 years are detailed here. Porous matrices from carbon, noble metals, and polymers promote the development of EBFCs through the electron transfer and mass transport benefits. Some key issues regarding how these nanostructured porous media improve the performance of EBFCs are also discussed.

Tyrosinase-catalyzed polymerization of l-DOPA (versusl-tyrosine and dopamine) to generate melanin-like biomaterials for immobilization of enzymes and amperometric biosensing

The tyrosinase-catalyzed polymerization of l-DOPA (versusl-tyrosine and dopamine) is recommended as an excellent system to immobilize enzymes for amperometric biosensing of catechol and glucose.

Manganese dioxide-core–shell hyperbranched chitosan (MnO2–HBCs) nano-structured screen printed electrode for enzymatic glucose biosensors

In this study, the synthesis, characterization and testing of new polymeric–metal oxide nanocomposites for enzymatic glucose biosensors were performed.

A compact photometer based on metal-waveguide-capillary: application to detecting glucose of nanomolar concentration

Trace analysis of liquid samples has wide applications in life science and environmental monitor. In this paper, a compact and low-cost photometer based on metal-waveguide-capillary (MWC) was developed for ultra-sensitive absorbance detection. The optical-path can be greatly enhanced and much longer than the physical length of MWC, because the light scattered by the rippled and smooth metal sidewall can be confined inside the capillary regardless of the incident-angle. For the photometer with a 7 cm long MWC, the detection limit is improved ~3000 fold compared with that of commercial spectrophotometer with 1 cm-cuvette, owing to the novel nonlinear optical-path enhancement as well as fast sample switching, and detecting glucose of a concentration as low as 5.12 nM was realized with conventional chromogenic reagent.

Immobilization of Enzymes by Electrochemical and Chemical Oxidative Polymerization of L-DOPA to Fabricate Amperometric Biosensors and Biofuel Cells

Electrochemical/chemical oxidative synthesis and biosensing/biofuel cell applications of poly(L-DOPA) (PD) are studied versus polydopamine (PDA) as a recent hotspot biomaterial. The enzyme electrode developed by coelectrodeposition of PD and glucose oxidase (GOx), uricase, or tyrosinase shows biosensing performance superior to that of the corresponding PDA-based enzyme electrode. The chemical oxidative polymerization of L-DOPA (PDC) by NaAuCl4 in GOx-containing neutral aqueous solution is used to immobilize GOx and gold nanoparticles (AuNPs). The thus-prepared chitosan (CS)/GOx-PDC-AuNPs/Au(plate)/Au electrode working in the first-generation biosensing mode responds linearly to glucose concentration with a sensitivity of 152 μA mM(-1) cm(-2), which is larger than those of the CS/GOx-PDAC-AuNPs/Au(plate)/Au electrode, the CS/GOx-poly(3-anilineboronic acid) (PABA)-AuNPs/Au(plate)/Au electrode, and the most reported GOx-based enzyme electrodes. This PDC-based enzyme electrode also works well in the second-generation biosensing mode and as an excellent bioanode in biofuel cell construction, probably because PD as an amino acid polymer has the higher biocompatibility and the more favorable affinity to the enzyme than PDA. The PD material of great convenience in synthesis, outstanding biocompatibility for preparing high-performance bionanocomposites, and strong capability of multifunctional coatings on many surfaces may find wide applications in diversified fields including biotechnology and surface-coating.