Recent Advances in the Construction of Flexible Sensors for Biomedical Applications.

The fabrication of flexible sensors is a potential way to promote the progress of modern social science and technology due to their wide applications in high-performance electronic equipment and devices. Flexible sensors based on organic materials combine the unique advantages of flexibility and low cost, increasing interest in healthcare monitoring, treatment, and human-machine interfaces. Advances in materials science and biotechnology have rapidly accelerated the development of bio-integrated multifunctional sensors and devices. Due to their excellent mechanical and electrical properties, many types of functional materials provided benefits for the construction of various sensors with improved flexibility and stretchability. In this review, recent advance in the fabrication of flexible sensors by using functional nanomaterials including nanoparticles, carbon materials, metal-organic materials, and polymers is presented. In addition, the potential biomedical applications of the fabricated flexible sensors for detecting gas molecules signals, small molecules, DNA/RNA, proteins, others are introduced and discussed.

Recent advances in the fabrication, functionalization, and bioapplications of peptide hydrogels.

Self-assembled peptide-based nanomaterials have exhibited wide application potential in the fields of materials science, nanodevices, biomedicine, tissue engineering, biosensors, energy storage, environmental science, and others. Due to their porous structure, strong mechanical stability, high biocompatibility, and easy functionalization, three-dimensional self-assembled peptide hydrogels revealed promising potential in bio-related applications. To present the advances in this interesting topic, we present a review on the synthesis and functionalization of peptide hydrogels, as well as their applications in drug delivery, antibacterial materials, cell culture, biomineralization, bone tissue engineering, and biosensors. Specifically, we focus on the fabrication methods of peptide hydrogels through physical, chemical, and biological stimulations. In addition, the functional design of peptide hydrogels by incorporation with polymers, DNA, protein, nanoparticles, and carbon materials is introduced and discussed in detail. It is expected that this work will be helpful not only for the design and synthesis of various peptide-based nanostructures and nanomaterials, but also for the structural and functional tailoring of peptide-based nanomaterials to meet specific demands.

The design and biomedical applications of self-assembled two-dimensional organic biomaterials.

The design and applications of some inorganic two-dimensional (2D) nanomaterials such as graphene, graphyne, and borophene have been widely studied in recent years. Meanwhile, it has been noticed that self-assembling two-dimensional organic biomaterials (2DOBMs) including films, membranes, nanosheets, nanoribbons, grids, arrays, and lattices based on various biomolecules also exhibited promising structures, functions, and applications. The in-depth studies on the self-assembly formation, structural and functional tailoring of 2DOBMs open new avenues for the next generation of novel nanomaterials with adjustable structure and functions, which would further promote the applications of 2DOBMs in materials science, nanodevices, energy and environmental science, biomedicine, tissue engineering, and analytical science. In this review, we summarize important information on the basic principles to fabricate self-assembling 2DOBMs based on peptides, proteins, DNA, RNA, viruses, and other biopolymers. The potential strategies and techniques for tailoring and controlling the structures and functions of 2DOBMs are presented and discussed further. The function-specific biomedical applications of 2DOBMs in biosensors, biomimetic mineralization, cell growth, drug/gene delivery, and bioimaging are also highlighted.

Biomimetic Hydroxyapatite on Graphene Supports for Biomedical Applications: A Review.

Hydroxyapatite (HA) has been widely used in fields of materials science, tissue engineering, biomedicine, energy and environmental science, and analytical science due to its simple preparation, low-cost, and high biocompatibility. To overcome the weak mechanical properties of pure HA, various reinforcing materials were incorporated with HA to form high-performance composite materials. Due to the unique structural, biological, electrical, mechanical, thermal, and optical properties, graphene has exhibited great potentials for supporting the biomimetic synthesis of HA. In this review, we present recent advance in the biomimetic synthesis of HA on graphene supports for biomedical applications. More focuses on the biomimetic synthesis methods of HA and HA on graphene supports, as well as the biomedical applications of biomimetic graphene-HA nanohybrids in drug delivery, cell growth, bone regeneration, biosensors, and antibacterial test are performed. We believe that this review is state-of-the-art, and it will be valuable for readers to understand the biomimetic synthesis mechanisms of HA and other bioactive minerals, at the same time it can inspire the design and synthesis of graphene-based novel nanomaterials for advanced applications.

Controlling the Self-Assembly of Biomolecules into Functional Nanomaterials through Internal Interactions and External Stimulations: A Review.

Biomolecular self-assembly provides a facile way to synthesize functional nanomaterials. Due to the unique structure and functions of biomolecules, the created biological nanomaterials via biomolecular self-assembly have a wide range of applications, from materials science to biomedical engineering, tissue engineering, nanotechnology, and analytical science. In this review, we present recent advances in the synthesis of biological nanomaterials by controlling the biomolecular self-assembly from adjusting internal interactions and external stimulations. The self-assembly mechanisms of biomolecules (DNA, protein, peptide, virus, enzyme, metabolites, lipid, cholesterol, and others) related to various internal interactions, including hydrogen bonds, electrostatic interactions, hydrophobic interactions, π⁻π stacking, DNA base pairing, and ligand⁻receptor binding, are discussed by analyzing some recent studies. In addition, some strategies for promoting biomolecular self-assembly via external stimulations, such as adjusting the solution conditions (pH, temperature, ionic strength), adding organics, nanoparticles, or enzymes, and applying external light stimulation to the self-assembly systems, are demonstrated. We hope that this overview will be helpful for readers to understand the self-assembly mechanisms and strategies of biomolecules and to design and develop new biological nanostructures or nanomaterials for desired applications.

Hierarchical nanomaterials via biomolecular self-assembly and bioinspiration for energy and environmental applications.

Bioinspired synthesis offers potential green strategies to build highly complex nanomaterials by utilizing the unique nanostructures, functions, and properties of biomolecules, in which the biomolecular recognition and self-assembly processes play important roles in tailoring the structures and functions of bioinspired materials. Further understanding of biomolecular self-assembly for inspiring the formation and assembly of nanoparticles would promote the design and fabrication of functional nanomaterials for various applications. In this review, we focus on recent advances in bioinspired synthesis and applications of hierarchical nanomaterials based on biomolecular self-assembly. We first discuss biomolecular self-assembly towards biological nanomaterials, in which the mechanisms and ways of biomolecular self-assembly as well as various self-assembled biomolecular nanostructures are demonstrated. Secondly, the bioinspired synthesis strategies including molecule-molecule interaction, molecule-material recognition, molecule-mediated nucleation and growth, and molecule-mediated reduction/oxidation are introduced and discussed. Meanwhile, typical examples and discussions on how biomolecular self-assembly inspires the formation of hierarchical hybrid nanomaterials are presented. Finally, the applications of bioinspired nanomaterials in biofuel cells, light-harvesting systems, batteries, supercapacitors, catalysis, water/air purification, and environmental monitoring are presented and discussed. We believe that this review will be very helpful for readers to understand the self-assembly of biomolecules and the biomimetic/bioinspired strategies for synthesizing hierarchical nanomaterials on the one hand, and on the other hand to design novel materials for extended applications in nanotechnology, materials science, analytical science, and biomedical engineering.

A simple electrochemical biosensor based on AuNPs/MPS/Au electrode sensing layer for monitoring carbamate pesticides in real samples.

A simple electrochemical biosensor for quantitative determination of carbamate pesticide was developed based on a sensing interface of citrate-capped gold nanoparticles (AuNPs)/(3-mercaptopropyl)-trimethoxysilane (MPS)/gold electrode (Au). The biosensor was fabricated by firstly assembling three-dimensional (3D) MPS networks on Au electrode and subsequently assembling citrate-capped AuNPs on 3D MPS network via AuS bond. The interface of AuNPs/MPS/Au was negatively charged originating from the citrate coated on AuNPs that would repulse the negatively charged ferricyanide ([Fe(CN)6](3-/4-)) to produce a negative response. In the presence of acetylcholinesterase (AChE) and acetylthiocholine (ATCl), the AChE catalyzes the hydrolysis of ATCl into positively charged thiocholine which would replace the citrate on AuNPs through the strong AuS bond and convert the negative charged surface to be positively charged. The resulted positively charged AuNPs/MPS/Au then attracted the [Fe(CN)6](3-/4-) to produce a positive response. Based on the inhibition of carbamate pesticides on the activity of AChE, the pesticide could be quantitatively determined at a very low potential. The linear range was from 0.003 to 2.00 µM. The sensing platform was also proved to be suitable for carbamate pesticides detection in practical sample.