Recent advances in amino acid-metal coordinated nanomaterials for biomedical applications

Metal and amino acid (AA),as two kinds of entities,have been widely involved in biomaterials and nano-medicines.Recently,the marriage of them has developed new nanoformulations,amino acid-metal coor-dinated nanomaterials (AMCNs),which show great biomedical application potential in cancer therapy,antibacterial applications,biomedical imaging,etc.With the respective characteristics of metal and AA with rich biological and chemical properties,AMCNs can not only act as drug carriers with specific tumor targeting ability,but also realize synergistic therapy and imaging-guided therapy.Although the design and synthesis of amino acid-metal coordinated nanomaterials have been in-depth investigated,there are few systematic reviews on their biomedical application.In this review,we give a comprehensive sum-mary of recent progresses in the design,fabrication,and biomedical applications of AMCNs.We also pro-pose the future outlooks and challenges in aforementioned field.We expect that this review would contribute some inspiration for future research and development for amino acid metal coordinated nanomaterials.     

Inorganic-organic hybrid nanomaterials for therapeutic and diagnostic imaging applications

Nanotechnology offers outstanding potential for future biomedical applications. In particular, due to their unique characteristics, hybrid nanomaterials have recently been investigated as promising platforms for imaging and therapeutic applications. This class of nanoparticles can not only retain valuable features of both inorganic and organic moieties, but also provides the ability to systematically modify the properties of the hybrid material through the combination of functional elements. Moreover, the conjugation of targeting moieties on the surface of these nanomaterials gives them specific targeted imaging and therapeutic properties. In this review, we summarize the recent reports in the synthesis of hybrid nanomaterials and their applications in biomedical areas. Their applications as imaging and therapeutic agents in vivo will be highlighted.     

An Update on Graphene-Based Nanomaterials for Neural Growth and Central Nervous System Regeneration

Thanks to their reduced size, great surface area, and capacity to interact with cells and tissues, nanomaterials present some attractive biological and chemical characteristics with potential uses in the field of biomedical applications. In this context, graphene and its chemical derivatives have been extensively used in many biomedical research areas from drug delivery to bioelectronics and tissue engineering. Graphene-based nanomaterials show excellent optical, mechanical, and biological properties. They can be used as a substrate in the field of tissue engineering due to their conductivity, allowing to study, and educate neural connections, and guide neural growth and differentiation; thus, graphene-based nanomaterials represent an emerging aspect in regenerative medicine. Moreover, there is now an urgent need to develop multifunctional and functionalized nanomaterials able to arrive at neuronal cells through the blood-brain barrier, to manage a specific drug delivery system. In this review, we will focus on the recent applications of graphene-based nanomaterials in vitro and in vivo, also combining graphene with other smart materials to achieve the best benefits in the fields of nervous tissue engineering and neural regenerative medicine. We will then highlight the potential use of these graphene-based materials to construct graphene 3D scaffolds able to stimulate neural growth and regeneration in vivo for clinical applications.     

Graphene: a versatile nanoplatform for biomedical applications

Graphene, with its excellent physical, chemical, and mechanical properties, holds tremendous potential for a wide variety of biomedical applications. As research on graphene-based nanomaterials is still at a nascent stage due to the short time span since its initial report in 2004, a focused review on this topic is timely and necessary. In this feature review, we first summarize the results from toxicity studies of graphene and its derivatives. Although literature reports have mixed findings, we emphasize that the key question is not how toxic graphene itself is, but how to modify and functionalize it and its derivatives so that they do not exhibit acute/chronic toxicity, can be cleared from the body over time, and thereby can be best used for biomedical applications. We then discuss in detail the exploration of graphene-based nanomaterials for tissue engineering, molecular imaging, and drug/gene delivery applications. The future of graphene-based nanomaterials in biomedicine looks brighter than ever, and it is expected that they will find a wide range of biomedical applications with future research effort and interdisciplinary collaboration.     

Preparation, properties and applications of polysaccharide nanocrystals in advanced functional nanomaterials: a review

Intensive exploration and research in the past few decades on polysaccharide nanocrystals, the highly crystalline nanoscale materials derived from natural resources, mainly focused originally on their use as a reinforcing nanophase in nanocomposites. However, these investigations have led to the emergence of more diverse potential applications exploiting the functionality of these nanomaterials. Based on the construction strategies of functional nanomaterials, this article critically and comprehensively reviews the emerging polysaccharide nanocrystal-based functional nanomaterials with special applications, such as biomedical materials, biomimetic optical nanomaterials, bio-inspired mechanically adaptive nanomaterials, permselective nanostructured membranes, template for synthesizing inorganic nanoparticles, polymer electrolytes, emulsion nano-stabilizer and decontamination of organic pollutants. We focus on the preparation, unique properties and performances of the different polysaccharide nanocrystal materials. At the same time, the advantages, physicochemical properties and chemical modifications of polysaccharide nanocrystals are also comparatively discussed in view of materials development. Finally, the perspective and current challenges of polysaccharide nanocrystals in future functional nanomaterials are outlined.     

Peptide-capped gold nanoparticles: towards artificial proteins

Peptides can be designed to form self-assembled monolayers on gold nanoparticles to give nanomaterials with some chemical properties analogous to those of proteins. A variety of molecular-recognition properties are readily integrated within the peptide monolayer. Monofunctionalized nanoparticles are obtained by using separation methods that have been optimized for proteins. Recent applications as artificial enzymes and artificial enzyme substrates are presented. The limitations and long-term potential of peptide-capped nanoparticles as artificial proteins are discussed.     

Relevant photovoltaic effect in N-doped CQDs/MoS2 (0D/2D) quantum dimensional heterostructure

In this work, a novel kind of solar cell based on the N-CQDs/MoS₂ (0D/2D) quantum dimensional heterostructure has been fabricated using a two-dimensional (2D) MoS₂ ultrathin layer and zero-dimensional (0D) Nitrogen-doped carbon quantum dots (N-CQDs). The combination of N-CQDs and MoS₂ offers good optical and electrical characteristics. The current-voltage (I–V) characteristics of the quantum dimensional heterostructure have been recorded in the dark and under the illumination of solar radiations. A significant current rectification ratio has been observed in dark I–V characteristics. Furthermore, a remarkable shift of ?13.49 mA in the I–V curve is observed on the exposure to solar radiation. The fabricated quantum dimensional heterostructure exhibits a significant power conversion efficiency (η) of 4.06% and an open-circuit voltage of 0.83 V. The external quantum efficiency (EQE) spectra support the recorded photovoltaic performance of the heterostructure. The aforementioned results could be ascribed to the effective separation of photogenerated electron-hole pairs at the junction contact. The N-CQDs serve as an electron blocking layer, preventing additional carrier recombination at the metal electrode. Our findings show that N-CQDs/MoS₂ heterostructure has a great potential in futuristic low-cost, non-toxic, and highly efficient solar cells for next-generation energy harvesting applications.     

Prussian Blue: A Nanozyme with Versatile Catalytic Properties

Nanozymes, nanomaterials with enzyme-like activities, are becoming powerful competitors and potential substitutes for natural enzymes because of their excellent performance. Nanozymes offer better structural stability over their respective natural enzymes. In consequence, nanozymes exhibit promising applications in different fields such as the biomedical sector (in vivo diagnostics/and therapeutics) and the environmental sector (detection and remediation of inorganic and organic pollutants). Prussian blue nanoparticles and their analogues are metal–organic frameworks (MOF) composed of alternating ferric and ferrous irons coordinated with cyanides. Such nanoparticles benefit from excellent biocompatibility and biosafety. Besides other important properties, such as a highly porous structure, Prussian blue nanoparticles show catalytic activities due to the iron atom that acts as metal sites for the catalysis. The different states of oxidation are responsible for the multicatalytic activities of such nanoparticles, namely peroxidase-like, catalase-like, and superoxide dismutase-like activities. Depending on the catalytic performance, these nanoparticles can generate or scavenge reactive oxygen species (ROS).     

Enzyme Mimic Nanomaterials and Their Biomedical Applications

Nanomaterials with enzyme-mimicking behavior (nanozymes) have attracted a lot of research interest recently. In comparison to natural enzymes, nanozymes hold many advantages, such as good stability, ease of production and surface functionalization. As the catalytic mechanism of nanozymes is gradually revealed, the application fields of nanozymes are also broadly explored. Beyond traditional colorimetric detection assays, nanozymes have been found to hold great potential in a variety of biomedical fields, such as tumor theranostics, antibacterial, antioxidation and bioorthogonal reactions. In this review, we summarize nanozymes consisting of different nanomaterials. In addition, we focus on the catalytic performance of nanozymes in biomedical applications. The prospects and challenges in the practical use of nanozymes are discussed at the end of this Minireview.     

Improving Colorimetric Assays through Protein Enzyme-Assisted Gold Nanoparticle Amplification

The discovery of the DNA-mediated assembly of gold nanoparticles was a great moment in the history of science; this understanding and chemical control enabled the rational design of functional nanomaterials as novel probes in biodetection. In contrast with conventional probes such as organic dyes, gold nanoparticles exhibit high photostability and unique size-dependent optical properties. Because of their high extinction coefficients and strong distance dependent optical properties, these nanoparticles have emerged over the past decade as a promising platform for rapid, highly sensitive colorimetric assays that allow for the visual detection of low concentrations of metal ions, small molecules, and biomacromolecules. These discoveries have deepened our knowledge of biological phenomena and facilitated the development of many new diagnostic and therapeutic tools. Despite these many advances and continued research efforts, current nanoparticle-based colorimetric detection systems still suffer from several drawbacks, such as limited sensitivity and selectivity. This Account describes the recent development of colorimetric assays based on protein enzyme-assisted gold nanoparticle amplification. The benefits of such detection systems include significantly improved detection sensitivity and selectivity. First, we discuss the general design of enzyme-modified nanoparticle systems in colorimetric assays. We show that a quantitative understanding of the unique properties of different enzymes is paramount for effective biological assays. We then examine the assays for nucleic acid detection based on different types of enzymes, including endonucleases, ligases, and polymerases. For each of these assays, we identify the underlying principles that contribute to the enhanced detection capability of nanoparticle systems and illustrate them with selected examples. Furthermore, we demonstrate that the combination of gold nanoparticles and specific enzymes can probe enzyme dynamics and function with high specificity, offering substantial advantages in both sensitivity and specificity over conventional detection methods. The screening of nuclease, methyltransferase, protease, and kinase activities can be colorimetrically performed in a straightforward manner. Finally, we discuss examples of colorimetric assays for metal ions and small molecules that constitute important advances toward visual monitoring of enzyme catalytic functions and gene expression. Although these enzyme-assisted assay methods hold great promise for myriad applications in biomedicine and bioimaging, the application of the described techniques in vivo faces formidable challenges. In addition, researchers do not fully understand the interactions of gold nanoparticles with enzyme molecules. This understanding will require the development of new techniques to probe enzyme substrate dynamics at the particle interface with higher spatial resolution and chemical specificity.     

Role of catalyst supports in biocatalysis

Biocatalysis utilizes enzymes and microbial cells as catalysts for a wide range of applications in biotechnology. Immobilization of biocatalysts on various materials has several advantages, including the capacity for reuse, quick reaction termination, easy biocatalyst recovery and operational stability. The present article focuses on the use of material supports for developing immobilized biocatalysts in applications related to energy, environment and chemical synthesis. The work provides a comprehensive overview of a broad class of materials, including organic, inorganic and composites, that have been shown to be prosperous candidates to support the immobilization of enzymes and microbial cells. It also highlights the properties of nanomaterial support such as large surface area and comfort compartment for immobilization. The availability of different types of materials as catalyst support provides an opportunity to understand and develop efficient biocatalytic systems. The choice of selecting a catalyst support will mostly depend on the interaction of the material with the enzyme or microbial cell. Finally, potential challenges, future approaches in developing immobilized biocatalytic systems for various applications and novel material supports are suggested. © 2022 Society of Chemical Industry (SCI).     

The Preliminary Study on the Proapoptotic Effect of Reduced Graphene Oxide in Breast Cancer Cell Lines

Breast cancer is the most common cancer diagnosed in women, however traditional therapies have several side effects. This has led to an urgent need to explore novel drug approaches to treatment strategies such as graphene-based nanomaterials such as reduced graphene oxide (rGO). It was noticed as a potential drug due to its target selectivity, easy functionalisation, chemisensitisation, and high drug-loading capacity. rGO is widely used in many fields, including biological and biomedical, due to its unique physicochemical properties. However, the possible mechanisms of rGO toxicity remain unclear. In this paper, we present findings on the cytotoxic and antiproliferative effects of rGO and its ability to induce oxidative stress and apoptosis of breast cancer cell lines. We indicate that rGO induced time- and dose-dependent cytotoxicity in MDA-MB-231 and ZR-75-1 cell lines, but not in T-47D, MCF-7, Hs 578T cell lines. In rGO-treated MDA-MB-231 and ZR-75-1 cell lines, we noticed increased induction of apoptosis and necrosis. In addition, rGO has been found to cause oxidative stress, reduce proliferation, and induce structural changes in breast cancer cells. Taken together, these studies provide new insight into the mechanism of oxidative stress and apoptosis in breast cancer cells.     

Aptamer-conjugated nanomaterials for bioanalysis and biotechnology applications

In recent years, nanomaterials have captured the attention of scientists from a wide spectrum of domains. With their unique properties, nanomaterials offer great promise for numerous applications, ranging from catalysis to energy harvesting and information technology. Functionalized with the desired biomolecules, nanomaterials can also be utilized for many biomedical applications. This paper summarizes recent achievements in the use of aptamer-conjugated nanomaterials for bioanalysis and biotechnology applications. First, we discuss the features and properties of aptamers and then illustrate the use of aptamer-conjugated nanomaterials as sensing platforms and delivery vehicles, emphasizing how such integration can result in enhanced sensitivity and selectivity.     

Polymer-supported enzymes: Achievements,problems and perspectives

Over the last two decades, intense research activity in the area of enzyme and cell immobilisation techniques has fostered the industrial application of several new enzyme-catalysed processes for chemical and pharmaceutical production, as well as for the food industry. Biosensors, based on immobilised enzymes or whole cells, are finding wide-spread applications in the analytical and biomedical fields. The recent remarkable progress attained in the development of recombinant DNA techniques promises to provide any enzyme having properties tailored to meet the specific demands of any user.     

Mesoporous silica nanoparticles for bioadsorption, enzyme immobilisation, and delivery carriers

Mesoporous silica nanoparticles (MSNs) provide a non-invasive and biocompatible delivery platform for a broad range of applications in therapeutics, pharmaceuticals and diagnosis. The creation of smart, stimuli-responsive systems that respond to subtle changes in the local cellular environment are likely to yield long term solutions to many of the current drug/gene/DNA/RNA delivery problems. In addition, MSNs have proven to be promising supports for enzyme immobilisation, enabling the enzymes to retain their activity, affording them greater potential for wide applications in biocatalysis and energy. This review provides a comprehensive summary of the advances made in the last decade and a future outlook on possible applications of MSNs as nanocontainers for storage and delivery of biomolecules. We discuss some of the important factors affecting the adsorption and release of biomolecules in MSNs and review of the cytotoxicity aspects of such nanomaterials. The review also highlights some promising work on enzyme immobilisation using mesoporous silica nanoparticles.     

Metal Sulfide Semiconductor Nanomaterials and Polymer Microgels for Biomedical Applications

The development of nanomaterials with therapeutic and/or diagnostic properties has been an active area of research in biomedical sciences over the past decade. Nanomaterials have been identified as significant medical tools with potential therapeutic and diagnostic capabilities that are practically impossible to accomplish using larger molecules or bulk materials. Fabrication of nanomaterials is the most effective platform to engineer therapeutic agents and delivery systems for the treatment of cancer. This is mostly due to the high selectivity of nanomaterials for cancerous cells, which is attributable to the porous morphology of tumour cells which allows nanomaterials to accumulate more in tumour cells more than in normal cells. Nanomaterials can be used as potential drug delivery systems since they exist in similar scale as proteins. The unique properties of nanomaterials have drawn a lot of interest from researchers in search of new chemotherapeutic treatment for cancer. Metal sulfide nanomaterials have emerged as the most used frameworks in the past decade, but they tend to aggregate because of their high surface energy which triggers the thermodynamically favoured interaction. Stabilizing agents such as polymer and microgels have been utilized to inhibit the particles from any aggregations. In this review, we explore the development of metal sulfide polymer/microgel nanocomposites as therapeutic agents against cancerous cells.     

Genotoxic and mutagenic activity of diamond nanoparticles in human peripheral lymphocytes in vitro

Carbon nanomaterials have the numerous applications in biomedical sciences and nanotechnology-based industries. Nanodiamonds due to their unique physico-chemical properties compared to other carbon nanomaterials are suggested to be better drug carriers or implant coating. Nevertheless, little is known about their short- and long-term toxicological effects on humans, other biological systems and surrounding environment. In the present study, we evaluated genotoxic and mutagenic potential of nanodiamond (particle size <10 nm) in human lymphocytes in vitro. Starting from concentration of 50 μg/ml, diamond nanopowder was cytotoxic, inhibited cell proliferation and induced apoptotic cell death. Nanodiamond-associated oxidative stress was revealed, the effect was dose-dependent and statistically significant. Nanodiamond-mediated DNA oxidative damage (8-oxoG level) and changes in chromatin stability was observed even at as low as 1 μg/ml concentration, which was especially seen for DNA single strand breaks estimated with alkaline comet assay. In contrast, no induction of DNA double strand breaks (neutral comet assay) was documented after nanodiamond treatment. Nanodiamond at concentration of 10 μg/ml was able to stimulate micronuclei production. Centromeric signals found in nanodiamond-induced micronuclei may be due to aneugenic activity of diamond nanopowder. Taken together, we showed that nanodiamond-mediated oxidative stress may contribute to DNA damage limiting nanodiamond biocompatibility.     

Ductile PLA modified with methacryloyloxyalkyl isocyanate improves mechanical properties

The majority of the biodegradable polymers in clinical use are composed of stiff materials that exhibit limited extendibility with unsuitably high Young’s modulus and low elongation at break values that make them non-optimal for various biomedical applications. Polylactide (PLA) is often used as a biomedical material because it is biodegradable, but the physical and mechanical properties of PLA need to be improved for biomedical applications. In order to improve the flexibility and strength of biodegradable PLA, various reaction conditions were studied. Urethane structure polymer materials were prepared; PLA was reacted with a small amount of methacryloyloxyethyl isocyanate (MOI) to obtain a ductile PLA with markedly improved mechanical properties. Elongation at break increased by 20 times when compared to neat PLA. Impact resistance (notched) improved 1.6 times. Thus, this modified PLA biodegradable polymer may have greater application as a biomedical material with increased mechanical properties.     

Immobilization of organophosphorus hydrolase enzyme by covalent attachment on modified cellulose microfibers using different chemical activation strategies: Characterization and stability studies

The plant cellulose powder was activated by two different methods using 1,4-butanediol diglycidyl ether(BTDE)and 1,1′-Carbonyldiimidazole(CDI) as the chemical coupling agents.Organophosphorus hydrolase(OPH) from Flavobacterium ATCC 27551 was immobilized on any of activated support through covalent bonding.The optimal conditions of affecting parameters on enzyme immobilization in both methods were found, and it was demonstrated that the highest activity yields of immobilized OPH onto epoxy and CDI treated cellulose were 68.32%and 73.51%, respectively.The surface treatment of cellulose via covalent coupling with BTDE and CDI agents was proved by FTIR analysis.The kinetic constants of the free and immobilized enzymes were determined, and it was showed that both immobilization techniques moderately increased the Kmvalue of the free OPH.The improvements in storage and thermal stability were investigated and depicted that the half-life of immobilized OPH over the surface of epoxy modified cellulose had a better growth compared to the free and immobilized enzymes onto CDI treated support.Also, the pH stability of the immobilized preparations was enhanced relative to the free counterpart and revealed that all enzyme samples would have the same optimum pH value for stability at 9.0.Additionally, the immobilized OPH onto epoxy and CDI activated cellulose retained about 59% and 68% of their initial activity after ten turns of batch operation, respectively.The results demonstrated the high performance of OPH enzyme in immobilized state onto an inexpensive support with the potential of industrial applications.     

Evidence for electro-chemical interactions between multi-walled carbon nanotubes and human macrophages

Carbon multi-walled nanotubes (MWCNTs) may have several dangerous effects on different cell systems, but the mechanisms responsible for their cytotoxicity are not well known yet. At present, very little is known about the electrical interactions between nanomaterials and cells. We aimed to verify whether MWCNT electrical properties could affect the so called “charge-sensitive” cell parameters, interacting with cellular electrical activity. Human macrophages were challenged with two fully characterised MWCNT samples, one tested as-prepared (MWCNT), the other one purified (by annealing at 2400 °C) and better electro-conductive (a-MWCNT). Our findings show that a-MWCNTs are less cytotoxic but possess a higher inflammatory potential, as compared to MWCNTs. Moreover, only annealed and better conductive MWCNTs affect significantly the mitochondrial membrane polarity, the intracellular pH and the reorganisation of cytoskeleton actin filaments, cell functions strictly dependent on electro-chemical mechanisms. Based on our results, there is evidence for electro-chemical interactions taking place between cell membranes and electro-conductive MWCNTs. Such a specific behaviour could have wide-range applications in the biomedical field, not only concerning those cellular systems (neuronal and bone cells) sensitive to electrical stimuli, but also other cell systems.