Luminescent supramolecular hydrogels from a tripeptide and nitrogen-doped carbon nanodots

Nanocomposite Hydrogels with Self-Assembling Peptide-Functionalized Carbon Nanostructures

Carbon nanostructures (CNSs) are attractive components to attain nanocomposites, yet their hydrophobic nature and strong tendency to aggregate often limit their use in aqueous conditions and negatively impact their properties. In this work, carbon nanohorns (CNHs), multi-walled carbon nanotubes (CNTs), and graphene (G) are first oxidized, and then reacted to covalently anchor the self-assembling tripeptide L-Leu-D-Phe-D-Phe to improve their dispersibility in phosphate buffer, and favor the formation of hydrogels formed by the self-organizing L-Leu-D-Phe-D-Phe present in solution. The obtained nanocomposites are then characterized by transmission electron microscopy (TEM), oscillatory rheology, and conductivity measurements to gain useful insights as to the key factors that determine self-healing ability for the future design of this type of nanocomposites.

Recent advances in modification of novel carbon-based composites: Synthesis, properties, and biotechnological/ biomedical applications

Nowadays, carbon-based materials owing to great interest in biomedical science/biotechnology and applied for effective diagnosis and treatment of disease. To enhance the effectiveness of carbon nanotubes (CNTs)/graphene-based materials for bio-medical science/technology applications, different kinds of surface modification/functionalization were developed for the attachment of metal oxides nanostructures, biomolecules and polymers. The attachment of pharmaceutical agents with CNTs/graphene, make it a favorable candidate in research field of bio-medical science/technology applications. Surface modified/functionalized CNTs and graphene derivatives materials integrated with pharmaceutical agents has been developed for the purpose of cancer therapy, antibacterial action, pathogens bio detection, drug and gene delivery. Surface modification or functionalization of CNT/graphene materials provides good platform for pharmaceutical agents attachment with improved surface Raman scattering, fluorescence and its quenching capability. Graphene-based biosensing and bioimaging technologies are widely applied to identify numerous trace level analytes. These fluorescent and electrochemical sensors are utilized primarily for detecting organic, inorganic, and biomolecules. In this article, we highlights and summarized overview of the current research progress concerned on the CNTs/graphene-based materials as a new generation materials for detection and treatment of diseases.

Hydrogels from a Self-Assembling Tripeptide and Carbon Nanotubes (CNTs): Comparison between Single-Walled and Double-Walled CNTs

Supramolecular hydrogels obtained from the self-organization of simple peptides, such as tripeptides, are attractive soft materials. Their viscoelastic properties can be enhanced through the inclusion of carbon nanomaterials (CNMs), although their presence can also hinder self-assembly, thus requiring investigation of the compatibility of CNMs with peptide supramolecular organization. In this work, we compared single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) as nanostructured additives for a tripeptide hydrogel, revealing superior performance by the latter. Several spectroscopic techniques, as well as thermogravimetric analyses, microscopy, and rheology data, provide details to elucidate the structure and behavior of nanocomposite hydrogels of this kind.

Self-Assembling Peptides and Carbon Nanomaterials Join Forces for Innovative Biomedical Applications

Self-assembling peptides and carbon nanomaterials have attracted great interest for their respective potential to bring innovation in the biomedical field. Combination of these two types of building blocks is not trivial in light of their very different physico-chemical properties, yet great progress has been made over the years at the interface between these two research areas. This concise review will analyze the latest developments at the forefront of research that combines self-assembling peptides with carbon nanostructures for biological use. Applications span from tissue regeneration, to biosensing and imaging, and bioelectronics.

Co-assembly and multicomponent hydrogel formation upon mixing nucleobase-containing peptides

Peptide-based hydrogels are physical gels formed through specific supramolecular self-assembling processes, leading to ordered nanostructures which constitute the water entrapping scaffold of the soft material. Thanks to the inherent properties of peptides, these hydrogels are highly considered in the biomedical domain and open new horizons in terms of application in advanced therapies and biotechnologies. The use of one, and only one, native peptide to formulate a gel is by far the most reported approach to design such materials, but suffers from several limitations, including in terms of mechanical properties. To improve peptide-based hydrogels interest and give rise to innovative properties, several strategies have been proposed in the recent years, and the development of multicomponent peptide-based hydrogels appears as a promising and relevant strategy. Indeed, mixing two or more compounds to develop new materials is a much-used approach that has proven its effectiveness in a wide variety of domains, including polymers, composites and alloys. While still limited to a handful of examples, we would like to report herein on the formulation and the comprehensive study of multicomponent hybrid DNA-nucleobase/peptide-based hydrogels using a multiscale approach based on a large panel of analytical techniques (i.e., rheometry, proton relaxometry, SAXS, electronic microscopy, infrared, circular dichroism, fluorescence, Thioflavin T assays). Among the six multicomponent systems studied, the results highlight the synergistic role of the presence of the two complementary DNA-nucleobases (i.e., adenine/thymine and guanine/cytosine) on the co-assembling process from structural (e.g., morphology of the nanoobjects) to physicochemical (e.g., kinetics of formation, fluorescence properties) and mechanical (e.g., stiffness, resistance to external stress) properties. All the data confirm the relevance of the multicomponent peptide-based approach in the design of innovative hydrogels and bring another brick in the wall of the understanding of these complex and promising systems.

Green Approaches to Carbon Nanostructure-Based Biomaterials

The family of carbon nanostructures comprises several members, such as fullerenes, nano-onions, nanodots, nanodiamonds, nanohorns, nanotubes, and graphene-based materials. Their unique electronic properties have attracted great interest for their highly innovative potential in nanomedicine. However, their hydrophobic nature often requires organic solvents for their dispersibility and processing. In this review, we describe the green approaches that have been developed to produce and functionalize carbon nanomaterials for biomedical applications, with a special focus on the very latest reports.

Biomass-Derived Nitrogen Functionalized Carbon Nanodots and Their Anti-Biofouling Properties

The prevalence of the antibiotic resistant bacteria remains a global issue. Cheap, sustainable and multifunctional antibacterial membranes are at the forefront of filtrating materials capable of treating multiple flow streams, such as water cleansing treatments. Carbon nanomaterials are particularly interesting objects shown to enhance antibacterial properties of composite materials. In this article, amino-functionalized, photoluminescent carbon nanodots (CNDs) were synthesized from chitosan by bottom-up approach via simple and green hydrothermal carbonization. A chemical model for the CNDs formation during hydrothermal treatment of chitosan is proposed. The use of urea as an additional nitrogen source leads to the consumption of hydroxyl groups of chitosan and higher nitrogen doping level as pyridinic and pyrrolic N-bonding configurations in the final carbonaceous composition. These functionalized carbon nanodots that consist of carbon core and various surface functional groups were used to modify the commercially available membranes in order to enhance their anti-biofouling properties and add possible functionalities, including fluorescent labelling. Incorporation of CNDs to membranes increased their hydrophilicity, surface charge without compromising membranes integrity, thereby increasing the factors affecting bacterial wall disruption. Membranes modified with CNDs effectively stopped the growth of two Gram-negative bacterial colonies: Klebsiella oxytoca (K. oxytoca) and Pseudomonas aeruginosa (P. aeruginosa).

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.

Improving and fine-tuning the properties of peptide-based hydrogels via incorporation of peptide nucleic acids

Peptide self-assemblies have attracted intense research interest over the last few decades thanks to their implications in key biological processes (e.g., amyloid formation) and their use in biotechnological and (bio)material fields. In particular, peptide-based hydrogels have been highly considered as high potential supramolecular materials in the biomedical domain and open new horizons in terms of applications. To further understand their self-assembly mechanisms and to optimize their properties, several strategies have been proposed with the modification of the constituting amino acid chains via, per se, the introduction of d-amino acids, halogenated amino acids, pseudopeptide bonds, or other chemical moieties. In this context, we report herein on the incorporation of DNA-nucleobases into their peptide nucleic acid (PNA) forms to develop a new series of hybrid nucleopeptides. Thus, depending on the nature of the nucleobase (i.e., thymine, cytosine, adenine or guanine), the physicochemical and mechanical properties of the resulting hydrogels can be significantly improved and fine-tuned with, for instance, drastic enhancements of both the gel stiffness (up to 70-fold) and the gel resistance to external stress (up to 40-fold), and the generation of both thermo-reversible and uncommon red-edge excitation shift (REES) properties. To decipher the actual role of each PNA moiety in the self-assembly processes, the induced modifications from the molecular to the macroscopic scales are studied thanks to the multiscale approach based on a large panel of analytical techniques (i.e., rheology, NMR relaxometry, TEM, thioflavin T assays, FTIR, CD, fluorescence, NMR chemical shift index). Thus, such a strategy provides new opportunities to adapt and fit hydrogel properties to the intended ones and pushes back the limits of supramolecular materials.

Tuning Surface Morphology of Fluorescent Hydrogels Using a Vortex Fluidic Device

In recent decades, microfluidic techniques have been extensively used to advance hydrogel design and control the architectural features on the micro- and nanoscale. The major challenges with the microfluidic approach are clogging and limited architectural features: notably, the creation of the sphere, core-shell, and fibers. Implementation of batch production is almost impossible with the relatively lengthy time of production, which is another disadvantage. This minireview aims to introduce a new microfluidic platform, a vortex fluidic device (VFD), for one-step fabrication of hydrogels with different architectural features and properties. The application of a VFD in the fabrication of physically crosslinked hydrogels with different surface morphologies, the creation of fluorescent hydrogels with excellent photostability and fluorescence properties, and tuning of the structure-property relationship in hydrogels are discussed. We conceive, on the basis of this minireview, that future studies will provide new opportunities to develop hydrogel nanocomposites with superior properties for different biomedical and engineering applications.

Current Use of Carbon-Based Materials for Biomedical Applications—A Prospective and Review

Among a large number of current biomedical applications in the use of medical devices, carbon-based nanomaterials such as graphene (G), graphene oxides (GO), reduced graphene oxide (rGO), and carbon nanotube (CNT) are frontline materials that are suitable for developing medical devices. Carbon Based Nanomaterials (CBNs) are becoming promising materials due to the existence of both inorganic semiconducting properties and organic π-π stacking characteristics. Hence, it could effectively simultaneously interact with biomolecules and response to the light. By taking advantage of such aspects in a single entity, CBNs could be used for developing biomedical applications in the future. The recent studies in developing carbon-based nanomaterials and its applications in targeting drug delivery, cancer therapy, and biosensors. The development of conjugated and modified carbon-based nanomaterials contributes to positive outcomes in various therapies and achieved emerging challenges in preclinical biomedical applications. Subsequently, diverse biomedical applications of carbon nanotube were also deliberately discussed in the light of various therapeutic advantages.

Supramolecular Tripeptide Hydrogel Assembly with 5-Fluorouracil

In this work, we present Thioflavin T fluorescence, transmission electron microscopy (TEM), circular dichroism (CD), Fourier-transformed infrared (FT-IR), and oscillatory rheometry studies applied to an antineoplastic drug, 5-fluorouracil (5-FU), embedded in a heterochiral tripeptide hydrogel to obtain a drug delivery supramolecular system. The release of 5-fluorouracil was monitored over time by reverse-phase high-performance liquid chromatography (HPLC) and its interaction with the tripeptide assemblies was probed by all-atom molecular dynamics simulations.

High-tolerance crystalline hydrogels formed from self-assembling cyclic dipeptide

Peptide-based supramolecular hydrogels, as a new type of biological nanoarchitectonic structure, hold great promise for a wide range of biomedical and nanotechnological applications, such as tissue engineering, drug delivery, and electronic and photonic energy storage. In this work, a cyclic dipeptide (CDP) cyclo-(Trp-Tyr) (C-WY), which has exceptional structural rigidity and high stability, is selected as a hydrogelator for the formation of supramolecular hydrogels. The unique hydrogen bonding in C-WY endows a high propensity for self-assembly and the resulting hydrogels are revealed to be crystalline. The crystalline hydrogels possess excellent mechanical capacity and superior tolerance to various harsh conditions, including in the presence of charged biopolymers, extreme acid/base environments, and changing thermal conditions. Such high tolerance enables the crystalline hydrogels to be applied in the complex and harsh environments of electrochemistry. In addition, this study demonstrates that the self-assembly of cyclic dipeptides results in highly robust hydrogels which can be applied for electrochemical applications such as electrochemical supercapacitors.

Biomedical Applications of Graphene-Based Structures

Graphene and graphene oxide (GO) structures and their reduced forms, e.g., GO paper and partially or fully reduced three-dimensional (3D) aerogels, are at the forefront of materials design for extensive biomedical applications that allow for the proliferation and differentiation/maturation of cells, drug delivery, and anticancer therapies. Various viability tests that have been conducted in vitro on human cells and in vivo on mice reveal very promising results, which make graphene-based materials suitable for real-life applications. In this review, we will give an overview of the latest studies that utilize graphene-based structures and their composites in biological applications and show how the biomimetic behavior of these materials can be a step forward in bridging the gap between nature and synthetically designed graphene-based nanomaterials.

Nanocellulose: Recent advances and its prospects in environmental remediation

Among many other sustainable functional nanomaterials, nanocellulose is drawing increasing interest for use in environmental remediation technologies due to its numerous unique properties and functionalities. Nanocellulose is usually derived from the disintegration of naturally occurring polymers or produced by the action of bacteria. In this review, some invigorating perspectives on the challenges, future direction, and updates on the most relevant uses of nanocellulose in environmental remediation are discussed. The reported applications and properties of nanocellulose as an adsorbent, photocatalyst, flocculant, and membrane are reviewed in particular. However, additional effort will be required to implement and commercialize nanocellulose as a viable nanomaterial for remediation technologies. In this regard, the main challenges and limitations in working with nanocellulose-based materials are identified in an effort to improve the development and efficient use of nanocellulose in environmental remediation.

Oxidized Nanocarbons-Tripeptide Supramolecular Hydrogels: Shape Matters!

Short peptide hydrogels are attractive biomaterials but typically suffer from limited mechanical properties. Inclusion of other nanomaterials can serve the dual purpose of hydrogel reinforcement and of conferring additional physicochemical properties ( e. g., self-healing, conductivity), as long as they do not hamper peptide self-assembly. In particular, nanocarbons are ideal candidates, and their physicochemical properties have demonstrated great potential in nanocarbon-polymer gel biomaterials for tissue engineering or drug delivery. Recently, increasing interest in supramolecular hydrogels drove research also on their enhancement with nanocarbons. However, little is known on the effect of nanocarbon morphology on the self-assembly of short peptides, which are among the most popular hydrogel building blocks. In this work, three different oxidized nanocarbons ( i. e., carbon nanotube or CNT as 1D material, graphene oxide sheet or GO as 2D material, and carbon nanohorn or CNH as 3D material) were evaluated for their effects on the self-assembly of the unprotected tripeptide Leu-^DPhe-^DPhe at physiological conditions. Supramolecular hydrogels were obtained in all cases, and viscoelastic properties were clearly affected by the nanocarbons, which increased stiffness and resistance to applied stress. Notably, self-healing behavior was observed only in the case of CNTs. Tripeptide-nanotube interaction was noted already in solution prior to self-assembly, with the tripeptide acting as a dispersing agent in phosphate buffer. Experimental and in silico investigation of the interaction between peptide and CNTs suggests that the latter acts as nucleation templates for self-assembly and reassembly. Overall, we provide useful insights for the future design of composite biomaterials with acquired properties.

Assembly of a Tripeptide and Anti-Inflammatory Drugs into Supramolecular Hydrogels for Sustained Release

Supramolecular hydrogels offer interesting opportunities for co-assembly with drugs towards sustained release over time, which could be achieved given that the drug participates in the hydrogel nanostructure, and it is not simply physically entrapped within the gel matrix. dLeu-Phe-Phe is an attractive building block of biomaterials in light of the peptide's inherent biocompatibility and biodegradability. This study evaluates the assembly of the tripeptide in the presence of either of the anti-inflammatory drugs ketoprofen or naproxen at levels analogous to commercial gel formulations. Fourier-transformed infrared (FT-IR), circular dichroism, Thioflavin T fluorescence, transmission electron microscopy (TEM), and oscillatory rheometry are used. Drug release over time is monitored by means of reverse-phase high performance liquid chromatography, and shows different kinetics for the two drugs.