Facile one-pot preparation of chitosan/calcium pyrophosphate hybrid microflowers

Magnetic nanoflowers: a hybrid platform for enzyme immobilization

The use of organic-inorganic hybrid nanoflowers as a support material for enzyme immobilization has gained significant attention in recent years due to their high stability, ease of preparation, and enhanced catalytic activity. However, a major challenge in utilizing these hybrid nanoflowers for enzyme immobilization is the difficulty in handling and separating them due to their low density and high dispersion. To address this issue, magnetic nanoflowers have emerged as a promising alternative enzyme immobilization platform due to their easy separation, structural stability, and ability to enhance catalytic efficiency. This review focuses on different methods for designing magnetic nanoflowers, as well as future research directions. Additionally, it provides examples of enzymes immobilized in the form of magnetic nanoflowers and their applications in environmental remediation, biosensors, and food industries. Finally, the review discusses possible ways to improve the material for enhanced catalytic activity, structural stability, and scalability.

Chitosan microflower-embedded gelatin sponges for advanced wound management and hemostatic applications

The study explored the antimicrobial, antibiofilm, and hemostatic properties of chitosan microflowers (CMF) in sponge form. The main objective was to enhance the preparation of CMF by employing varying quantities of calcium chloride (CaCl2) and tripolyphosphate (TPP). CMF was then combined with gelatin (GE) in different proportions to produce three sponge samples: CMF0@GE, CMF1@GE, and CMF2@GE. The CMF had a morphology like that of a flower and produced surfaces with a porous sponge-like structure. The antibacterial activity, as determined by the zone of inhibition (ZOI), increased with greater doses of CMF. Among the tested samples, CMF2@GE had the greatest activity against Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecium. CMF2@GE successfully suppressed biofilm formation, decreased clotting time to an average of 212.67 s, and exhibited excellent biocompatibility by preserving over 90 % viability of human skin fibroblast cells at dosages below 100 μg/mL. The results indicated that gelatin sponges filled with CMF have considerable promise as flexible medical instruments for wound healing and infection control.

Gelatin-Zinc Carrier as a New Method of Targeted and Controlled Release of Risedronate

The essence of drug delivery is to use an appropriate carrier that delivers the active substance to the appropriate pathogenic site at a specific time. This study aims to develop a novel drug carrier characterized by the controlled and targeted release of risedronate (RSD). The search for new routes to deliver RSD is important because oral delivery has many disadvantages. The carrier proposed in this work is composed of gelatin, polyphosphates, and zinc. The zinc contained in the carrier is responsible for coordinating the drug. The resulting material releases RSD in a controlled manner. The rate of delivery of the substance to the body depends on the pH of the environment. This study investigated the delivery of RSD in a neutral environment, where the process exhibited a prolonged and consistent release rate. This process has also been studied in an acidic environment, which accelerates the release of the drug. Mixed-environment studies were also conducted. Initially, the drug was released in a neutral environment, and then the conditions rapidly changed to acidic. In this case, the carrier demonstrated high stability and controlled release, adapting the rate of drug release to the prevailing environmental conditions. The presented results indicate the great potential of the new gelatin-based carrier in the delivery of risedronate.

Immobilized Dipeptidase in Manganese Ion-Loaded Polyethylenimine-Induced Calcium Phosphate Nanocrystals for Carnosine Synthesis

Carnosine is a natural bioactive dipeptide with important physiological functions widely used in food and medicine. Dipeptidase (PepD) from Serratia marcescens can catalyze the reverse hydrolytic reaction of β-alanine with l-histidine to synthesize carnosine in the presence of Mn2+. However, it remains challenging to practice carnosine biosynthesis due to the low activity and high cost of the enzyme. Therefore, the development of biocatalysts with high activity and stability is of significance for carnosine synthesis. Here, we proposed to chelate Mn2+ to polyethylenimine (PEI) that induced rapid formation of calcium phosphate nanocrystals (CaP), and Mn-PEI@CaP was used for PepD immobilization via electrostatic interaction. Mn-PEI@CaP as the carrier enhanced the stability of the immobilized enzyme. Moreover, Mn2+ loaded in the carrier acted as an in situ activator of the immobilized PepD for facilitating the biocatalytic process of carnosine synthesis. The as-prepared immobilized enzyme (PepD-Mn-PEI@CaP) kept similar activity with free PepD plus Mn2+ (activity recovery, 102.5%), while exhibiting elevated thermal stability and pH tolerance. Moreover, it exhibited about two times faster carnosine synthesis than the free PepD system. PepD-Mn-PEI@CaP retained 86.8% of the original activity after eight cycles of batch catalysis without the addition of free Mn2+ ions during multiple cycles. This work provides a new strategy for the co-immobilization of PepD and Mn2+, which greatly improves the operability of the biocatalysis and demonstrates the potential of the immobilized PepD system for efficient carnosine synthesis.

Hyperactivation of lipases by immobilization on superhydrophobic graphene quantum dots inorganic hybrid nanoflower

Various nanoflowers are synthesized for enzyme immobilization. In order to increase the activity of nanoflowers, in this study, 3D flower-like structured organic-inorganic hybrid nanoflowers (hNFs) with various lipases Rhizomucor miehei lipase (RML), Candida antarctica lipase B (CALB), Humicola insolens lipase (HIL), Thermomyces lanuginosus lipase (TLL), Eversa® Transform 2.0 (ET) a genetically modified enzyme derived of TLL and graphene quantum dots (GQDs) were prepared and characterized.Lipase hNFs [lipase-(Cu/Co)3(PO4)2] and lipase@GQDs hNFs [lipase@GQDs-(Cu/Co)3(PO4)2] were straightforwardly prepared through mixing with metal ion (Cu2+or Co2+) aqueous solutions with or without GQDs. The ET@GQDs-(Cu)3(PO4)2 hNFs demonstrated 687 % higher activity than ET-(Cu)3(PO4)2 hNFs and 650 % higher activity than the free ET. Similar results were also observed with other lipase hybrid nanoflowers. For example, TLL@GQDs-(Cu)3(PO4)2 hNFs exhibited a 557 % higher activity than TLL-(Cu)3(PO4)2 hNFs and a 463 % higher activity than free TLL. Additionally, TLL@GQDs-(Co)3(PO4)2 hNFs showed a 141 % higher activity than TLL-(Co)3(PO4)2 hNFs and a 304 % higher activity than free TLL. Upon examining pH and thermal stability, it was revealed that lipase@GQDs hNFs exhibited higher activity compared to free lipase and other hNFs without GQDs. The effect of metal ions, enzyme concentrations and amount of GQDs on the morphology and enzyme activity of the lipase-hNFs was examined.

Bovine Serum Albumin - Hydroxyapatite Nanoflowers as Potential Local Drug Delivery System of Ciprofloxacin

Introduction

Hybrid nanoflowers are structures consisting of organic (enzymes, proteins, nucleic acids) and inorganic components (mostly metal phosphates) with a flower-like hierarchical structure. Novel hybrid nanoflowers based on bovine serum albumin (BSA) and hydroxyapatite (HA) were obtained and characterized. Study on BSA-HA nanoflowers as potential drug delivery system is reported for the first time.

Methods

Embedding ciprofloxacin in the structure of hybrid nanoflowers was confirmed by ATR-FTIR and thermogravimetric analysis. The inorganic phase of the nanoflowers was determined by X-ray diffraction. UV‒Vis spectroscopy was used to evaluate the release profiles of ciprofloxacin from nanoflowers in buffer solutions at pH 7.4 and 5. The agar disk diffusion method was used to study the antibacterial activity of the synthesized nanoflowers against Staphylococcus aureus and Pseudomonas aeruginosa.

Results

Bovine serum albumin - hydroxyapatite nanoflowers were obtained with diameters of ca. 1-2 µm. The kinetics of ciprofloxacin release from nanoflowers were described by the Korsmeyer-Peppas model. The antibacterial activity of the synthesized nanoflowers was demonstrated against S. aureus and P. aeruginosa, two main pathogens found in osteomyelitis.

Conclusion

The formulated nanoflowers may act as an efficient local antibiotic delivery system. Due to the use of nonhazardous, biodegradable components and benign synthesis, hybrid nanoflowers are very promising drug delivery systems that could be applied in the treatment of skeletal system infections.

Novel biocatalysts based on enzymes in complexes with nano- and micromaterials

In today's world, there is a wide array of materials engineered at the nano- and microscale, with numerous applications attributed to these innovations. This review aims to provide a concise overview of how nano- and micromaterials are utilized for enzyme immobilization. Enzymes act as eco-friendly biocatalysts extensively used in various industries and medicine. However, their widespread adoption faces challenges due to factors such as enzyme instability under different conditions, resulting in reduced effectiveness, high costs, and limited reusability. To address these issues, researchers have explored immobilization techniques using nano- and microscale materials as a potential solution. Such techniques offer the promise of enhancing enzyme stability against varying temperatures, solvents, pH levels, pollutants, and impurities. Consequently, enzyme immobilization remains a subject of great interest within both the scientific community and the industrial sector. As of now, the primary goal of enzyme immobilization is not solely limited to enabling reusability and stability. It has been demonstrated as a powerful tool to enhance various enzyme properties and improve biocatalyst performance and characteristics. The integration of nano- and microscale materials into biomedical devices is seamless, given the similarity in size to most biological systems. Common materials employed in developing these nanotechnology products include synthetic polymers, carbon-based nanomaterials, magnetic micro- and nanoparticles, metal and metal oxide nanoparticles, metal-organic frameworks, nano-sized mesoporous hydrogen-bonded organic frameworks, protein-based nano-delivery systems, lipid-based nano- and micromaterials, and polysaccharide-based nanoparticles.

Rescuing Nucleus Pulposus Cells From Senescence via Dual-Functional Greigite Nanozyme to Alleviate Intervertebral Disc Degeneration

High levels of reactive oxygen species (ROS) lead to progressive deterioration of mitochondrial function, resulting in tissue degeneration. In this study, ROS accumulation induced nucleus pulposus cells (NPCs) senescence is observed in degenerative human and rat intervertebral disc, suggesting senescence as a new therapeutic target to reverse intervertebral disc degeneration (IVDD). By targeting this, dual-functional greigite nanozyme is successfully constructed, which shows the ability to release abundant polysulfides and presents strong superoxide dismutase and catalase activities, both of which function to scavenge ROS and maintain the tissue at physical redox level. By significantly lowering the ROS level, greigite nanozyme rescues damaged mitochondrial function in IVDD models both in vitro and in vivo, rescues NPCs from senescence and alleviated the inflammatory response. Furthermore, RNA-sequencing reveals ROS-p53-p21 axis is responsible for cellular senescence-induced IVDD. Activation of the axis abolishes greigite nanozyme rescued NPCs senescence phenotype, as well as the alleviated inflammatory response to greigite nanozyme, which confirms the role of ROS-p53-p21 axis in greigite nanozyme's function to reverse IVDD. In conclusion, this study demonstrates that ROS-induced NPCs senescence leads to IVDD and the dual-functional greigite nanozyme holds strong potential to reverse this process, providing a novel strategy for IVDD management.

Zinc oxide nano-flowers improve the growth and propagation of mulberry cuttings grown under different irrigation regimes by mitigating drought-related complications and enhancing zinc uptake

Silkworm larvae mainly consume mulberry leaves; therefore, mulberry cultivation is important for the production of raw silk. Drought stress and micronutrient deficiency (Zn) are known to affect the propagation of mulberry cuttings. In this purview, the current investigation attempted to inspect the efficacy of different concentrations of zinc oxide nano-flower (ZnNFs) applied through both soil admixture and foliar spray on the propagation of mulberry cuttings grown under deficit irrigation regimes. The overall results demonstrated that the ZnNF-treated plant cuttings were well-adapted to drought stress and performed better in comparison to the control set. Out of the tested concentrations - ZnNF-10 (applied as 10 mg/kg soil and 10 ppm as foliar spray thrice) was found to be optimum, showing relatively better initial root establishment, the emergence of leaves, and survival and sprouting percentage. Further studies also confirmed an improvement in the accumulation of photosynthetic pigments, carbohydrates, and protein content even under extreme drought conditions. Most importantly, the ZnNF-10 treatment contributed to ROS detoxification and cell membrane protection by enhancing the pool of antioxidant enzymes. The study further demonstrated that ZnNF-10 application enhanced zinc content by 147.50%, 179.49%, and 171.99% in root, shoot, and leaves of the treated cuttings; thereby, improving the bioaccumulation factor of the plant parts. All of these interactive phenomena led to an increment in shoot height, biomass, leaf area, and leaf number of cuttings. These findings, therefore, indicated that ZnNFs can be developed as a promising nano-fertilizer for mulberry growth facilitating Zn uptake and mitigation of drought-induced complications.

Nanozymes and nanoflower: Physiochemical properties, mechanism and biomedical applications

Natural enzymes possess several drawbacks which limits their application in industries, wastewater remediation and biomedical field. Therefore, in recent years researchers have developed enzyme mimicking nanomaterials and enzymatic hybrid nanoflower which are alternatives of enzyme. Nanozymes and organic inorganic hybrid nanoflower have been developed which mimics natural enzymes functionalities such as diverse enzyme mimicking activities, enhanced catalytic activities, low cost, ease of preparation, stability and biocompatibility. Nanozymes include metal and metal oxide nanoparticles mimicking oxidases, peroxidases, superoxide dismutase and catalases while enzymatic and non-enzymatic biomolecules were used for preparing hybrid nanoflower. In this review nanozymes and hybrid nanoflower have been compared in terms of physiochemical properties, common synthetic routes, mechanism of action, modification, green synthesis and application in the field of disease diagnosis, imaging, environmental remediation and disease treatment. We also address the current challenges facing nanozyme and hybrid nanoflower research and the possible way to fulfil their potential in future.

Hybridization of laccase with dendrimer-grafted silica-coated hercynite-copper phosphate magnetic hybrid nanoflowers and its application in bioremoval of gemifloxacin

Laccase was successfully hybridized with polyamidoamine (PAMAM) dendrimer-grafted silica-coated hercynite-copper phosphate magnetic hybrid nanoflowers (MHNFs) to increase the catalytic performance of the enzyme and apply in an effective bioremoval of gemifloxacin. For this purpose, the magnetic nanoparticles (MNPs) of hercynite were covered with a silica layer, and the core-shell SiO₂@hercynite was then modified with PAMAM dendrimer to increase the surface area of the carrier for the enzyme attachment. Subsequently, the whole complex was hybridized with laccase and copper phosphate to attain a large surface area (104.3 m² g^-1). The fabricated MHNFs acquired the entrapment yield and efficiency of 90 ± 3% and 66 ± 5%, respectively. The catalytic activity of the fabricated biocatalyst was remained up to 50% after 13 reusability cycles. Approximately 90% of gemifloxacin was removed by the constructed MHNFs after 3 h incubation by adsorption and degradation mechanisms. The biotransformation products were then identified, and degradation pathways were proposed as defluorination, decarboxylation, elimination of a cyclopropyl group, and cleavage of the pyrrolidine moiety. Furthermore, the toxicity of gemifloxacin was effectively diminished against some bacterial strains.

An investigated organic and inorganic reinforcement as an effective economical filler of poly (methyl methacrylate) nanocomposites

Polymer matrix composites have garnered the interest of the dentistry sector. Nano-fillers are frequently used as reinforcements in these composites to enhance their characteristics. Poly (methyl methacrylate) was filled with date seed nanoparticles (DSNP) and titanium oxide nanoparticles (TiO₂NP). In this work, two nanofillers (DSNP and TiO₂NP) were analyzed using Fourier-transform infrared spectroscopy (FTIR). In addition, the features of the PMMA-nanofiller composite were experimentally evaluated via compression, micro-hardness, wear rate (WR), and coefficients of friction (µ) testing. Utilizing a scanning electron microscope (SEM), the microstructure of the PMMA-DSNP composite was examined. The results of the experiments on the nanocomposites demonstrated that the elastic modulus, microhardness, wear resistance, and friction resistance increased with an increase in DSNP content to 1.2 wt, in comparison to TiO₂NP at the same concentration. Finally, according to the guidelines, the ideal weight was determined to be 1.2 wt%, filler in the form of DSNP, at a normal load of 10 N.

TiO2 nanoflower photocatalysts: Synthesis, modifications and applications in wastewater treatment for removal of emerging organic pollutants

Titanium dioxide (TiO₂) has been considered as one of the most promising photocatalysts nanomaterials and is being used in a variety of fields of energy and environment under sunlight irradiation via photocatalysis. Highly efficient photocatalytic materials require the design of the proper structure with excellent morphology, interfacial structures, optical and surface properties, etc. Which are the key points to realize effective light-harvesting for photocatalytic applications. Hierarchical TiO₂ based nanoflower structures (i.e., 3D nanostructures) possess such characteristics and have attracted much attention in recent years. The uniqueness of TiO₂ nanoflowers (NFs) with a coarse texture and arranged structures demonstrates higher photocatalytic activity. This review deals with the hydrothermal synthesis of 3D TiO₂ NFs and effect of shape/size as well as various key synthesis parameters to improve their optoelectronic and photocatalytic properties. Furthermore, to improve their photocatalytic properties, various strategies such as doping engineering and heterojunction/nanocomposite formation with other functional nanomaterials have been discussed followed by their potential applications in photocatalytic degradation of various emerging pollutants discharged into the wastewater from various sources. Importance of such 3D nanoarchitecutres and future research in other fields of current interest in environments are discussed.

Chitosan-regulated biomimetic hybrid nanoflower for efficiently immobilizing enzymes to enhance stability and by-product tolerance

Organic-inorganic hybrid nano-materials have been considered to be promising immobilization matrixes for enzymes due to their significantly enhanced reusability and stability of enzymes. Herein, we constructed a novel organic-inorganic hybrid nanoflower via biomacromolecule-regulated biomimetic mineralization to immobilize sucrose phosphorylase (SPase). It was found that chitosan (CS) effectively regulated the biomimetic mineralization of calcium phosphate (CaP), leading to the formation of flower-like hybrid materials for the entrapment of SPase via self-assembly to establish a nano-biocatalyst (CS-CaP@SPase). Upon immobilization, the obtained CS-CaP@SPase exhibited excellent pH, by-product and organic solvents tolerance, and storage stability. Specifically, at acidic condition (pH 4), CS-CaP@SPase performed over 80 % of initial activity, which was 2.42-folds higher than that of free SPase. The catalytic activity of free SPase was severely inhibited about 30 % in the presence of fructose (1.2 M), but CS-CaP@SPase only lost 5 % relative activity. The CS-CaP@SPase retained over 80 % of its relative activity, while the free SPase maintained <20 % of its relative activity in acetonitrile. The relative activity of CS-CaP@SPase was still retained about 80 % after 10 cycles and maintained 75 % after 15 days. Based on Raman spectra analysis, it was also found that the increased β-folding component of SPase in the secondary structure after immobilization was the main factor for its enhanced stability. It is reasonable to believe that biomacromolecule-regulated biomimetic mineralization could be potentially used as a promising method to immobilize enzymes with excellent stability and recyclability, thereby facilitating the preparation of highly efficient catalysts for industrial biocatalysts, biosensing, and biomedicine.

Recent Advancements in Enzyme‐Incorporated Nanomaterials: Synthesis, Mechanistic Formation and Applications

Over the past decade, nanotechnology has been developed and employed across various entities. Among the numerous nanostructured material types, enzyme‐incorporated nanomaterials have shown great potential in various fields, as an alternative to biologically derived as well as synthetically developed hybrid structures. The mechanism of incorporating enzyme onto a nanostructure depends on several factors including the method of immobilization, type of nanomaterial, as well as operational and environmental conditions. The prospects of enzyme‐incorporated nanomaterials have shown promising results across various applications, such as biocatalysts, biosensors, drug therapy, and wastewater treatment. This is due to their excellent ability to exhibit chemical and physical properties such as high surface‐to‐volume ratio, recovery and/or reusability rates, sensitivity, response scale, and stable catalytic activity across wide operating conditions. In this review, the evolution of enzyme‐incorporated nanomaterials along with their impact on our society due to its state‐of‐the‐art properties, and its significance across different industrial applications are discussed. In addition, the weakness and future prospects of enzyme‐incorporated nanomaterials were also discussed to guide scientists for futuristic research and development in this field.

Chitosan/Calcium-Coated Ginsenoside Rb1 Phosphate Flower-like Microparticles as an Adjuvant to Enhance Immune Responses

Simple Summary

The field-level control over IBD is primarily via vaccination. The development of high effective IBV vaccine has drawing great attentions worldwide. Herein, the GRb1 was encap-sulated into Calcium phosphate and chitosan core-structure nanoparticles microspheres, which con-stitute a novel system for nanoparticle delivery (GRb1/IL-4@CS/Cap). The new nano-adjuvant de-livery system could induce the activation of chicken dendritic cells ( DCs ), with up-regulate the expression of MHC II and CD80, and increase the production of IL-1β and TNF-α. At the same time, it can trigger higher levels of IBDV-specific IgG and higher IgG2a/IgG1 ratio, and promote the production of IFN-γ, TNF-α, IL-4, IL-6, IL-1α, and IL-1βand other cytokines in chicken serum after vaccination, it provides an effective adjuvant system for the development of chicken IBDV attenu-ated vaccine.

Abstract

Infectious bursal disease (IBD) is a highly contagious immunocompromising disorder that caused great economic losses in the poultry industry. The field-level control over IBD is primarily via vaccination. The development of a highly effective IBV vaccine has drawn great attention worldwide. Chitosan/Calcium Phosphate (CS/CaP) nanoparticle was a newly developed effective biological delivery system for drug and antigen. Ginsenoside Rb1 is one of the main bioactive components of ginseng root extract, which has antioxidant, anti-inflammatory and immunological enhancement effects. Until now, the combined effect of CS/CaP and ginsenoside Rb1 on the chicken immune response had remained unknown. In this study, the GRb1 and IL-4 were encapsulated into Calcium phosphate and chitosan core structure nanoparticles microspheres (GRb1/IL-4@CS/CaP), and the effect of a newly developed delivery system on an infectious bursal disease virus (IBDV) attenuated vaccine was further evaluated. The results demonstrated that GRb1/IL-4@CS/CaP treatment could induce the activation of chicken dendritic cells (DCs), with the upregulated expression of MHCII and CD80, and the increased production of IL-1β and TNF-α. Importantly, GRb1/IL-4@CS/CaP could trigger a higher level of IBDV-specific IgG and a higher ratio of IgG2a/IgG1 than the traditional adjuvant groups, promoting the production of cytokine, including IFN-γ, TNF-α, IL-4, IL-6, IL-1α, and IL-1β, in chicken serum after 28 d and 42 d post-vaccine. Taken in all, GRb1/IL-4@CS/CaP could elicit prolonged vigorous immune responses for IBDV attenuated vaccine in chicken, which might provide an effective adjuvant system for avian vaccine development.

Chitosan-CaP microflowers and metronidazole loaded calcium alginate sponges with enhanced antibacterial, hemostatic and osteogenic properties for the prevention of dry socket after tooth removal

Tooth removal, particularly for patients with severe periodontitis, can frequently cause massive bleeding, postoperative infection, and bone resorption, resulting in a dry socket. Thus, developing bio-multifunctional materials with excellent antibacterial, hemostatic, and osteogenic characteristics for the prevention of dry sockets after tooth removal is highly desirable in clinical applications. Herein, chitosan-CaP microflowers (CM) and metronidazole (MD) loaded calcium alginate (CA) sponges (CA@CM/MD) with enhanced antibacterial, hemostatic, and osteogenic properties were developed via Ca²⁺ crosslinking, lyophilization, and electrostatic interaction for the prevention of dry socket after tooth removal. The fabricated CM particles display 3-dimensional, relatively homogeneous, and flower-shaped architectures. The CA@CM/MD composite sponges were facilely shaped into the tooth root as well as exhibit interconnected porous and lamellar structures with remarkable porosity, suitable maximum swelling ratio, as well as excellent compressive and hemostatic performance. Besides, the in vitro cellular assessment demonstrates that the prepared CA@CM/MD composite sponges possess satisfactory cytocompatibility. Importantly, the designed sponges significantly suppress the growth of S. aureus and E. coli, as well as promote cellular osteogenic differentiation by upregulating the formation of alkaline phosphatase. Our findings indicate that the tooth root-shaped composite sponges hold great promise for wound management after tooth removal.

Redox-Active Metaphosphate-Like Terminals Enable High-Capacity MXene Anodes for Ultrafast Na-Ion Storage

2D transition metal carbides and/or nitrides, so-called MXenes, are noted as ideal fast-charging cation-intercalation electrode materials, which nevertheless suffer from limited specific capacities. Herein, it is reported that constructing redox-active phosphorus-oxygen terminals can be an attractive strategy for Nb₄ C₃ MXenes to remarkably boost their specific capacities for ultrafast Na⁺ storage. As revealed, redox-active terminals with a stoichiometric formula of PO₂ - display a metaphosphate-like configuration with each P atom sustaining three PO bonds and one PO dangling bond. Compared with conventional O-terminals, metaphosphate-like terminals empower Nb₄ C₃ (denoted PO₂ -Nb₄ C₃ ) with considerably enriched carrier density (fourfold), improved conductivity (12.3-fold at 300 K), additional redox-active sites, boosted Nb redox depth, nondeclined Na⁺ -diffusion capability, and buffered internal stress during Na⁺ intercalation/de-intercalation. Consequently, compared with O-terminated Nb₄ C₃ , PO₂ -Nb₄ C₃ exhibits a doubled Na⁺ -storage capacity (221.0 mAh g^-1 ), well-retained fast-charging capability (4.9 min at 80% capacity retention), significantly promoted cycle life (nondegraded capacity over 2000 cycles), and justified feasibility for assembling energy-power-balanced Na-ion capacitors. This study unveils that the molecular-level design of MXene terminals provides opportunities for developing simultaneously high-capacity and fast-charging electrodes, alleviating the energy-power tradeoff typical for energy-storage devices.

Diatom Mediated Production of Fluorescent Flower Shaped Silver-Silica Nanohybrid

Fabrication of flower-like nanostructures are gaining attention because of their high surface/volume ratio and extensive adsorption capacity. In the present investigation, flower-shaped, autofluorescent silver-silica (Ag-SiO₂) hybrid nanoparticles have been fabricated exploiting diatoms as a source of nanosilica. Two different species of Gedaniella including G. flavovirens and G. mutabilis showed their efficacy in synthesizing fluorescent Ag-SiO₂ nanoflowers (NFs) and nanospheres (NSs) against 9 mM silver nitrate solution, respectively. The biogenic nanoconjugate (Ag-SiO₂) was characterized by Uv-vis spectroscopy, energy dispersive X-ray spectroscopy (EDS), scanning (SEM) and transmission (TEM) electron microscopy. Production of Ag-SiO₂ hybrid nanoparticle was confirmed by observing both Ag and Si signals from a single nanoparticle in an EDS study. The broad and single absorption band at ~420 nm in Uv-vis spectroscopy confirmed proper miscibility and production of hybrid nanoparticles. The Ag-SiO₂ nanohybrids revealed autofluorescent property under the blue light region (excitation ~450–490 nm). SEM images of particles synthesized by G. flavovirens revealed the production of microscopic flower shaped Ag-SiO₂ particles with several layers of petals. A TEM study confirmed that the synthesized Ag-SiO₂ NFs are variable in size with 100–500 nm in diameter. Decolorization of methylene blue after exposure to Ag-SiO₂ particles confirmed catalytic activity of synthesized nanostructures. This eco-friendly method provides a new dimension in nanobiotechnology for biogenesis of such hierarchical nanostructure in a cost-effective way.

Recent advances in carbon nanotubes-based biocatalysts and their applications

Enzymes have been incorporated into a wide variety of fields and industries as they catalyze many biochemical and chemical reactions. The immobilization of enzymes on carbon nanotubes (CNTs) for generating nano biocatalysts with high stability and reusability is gaining great attention among researchers. Functionalized CNTs act as excellent support for effective enzyme immobilization. Depending on the application, the enzymes can be tailored using the various surface functionalization techniques on the CNTs to extricate the desirable characteristics. Aiming at the preparation of efficient, stable, and recyclable nanobiocatalysts, this review provides an overview of the methods developed to immobilize the various enzymes. Various applications of carbon nanotube-based biocatalysts in water purification, bioremediation, biosensors, and biofuel cells have been comprehensively reviewed.

Dopamine-Mediated Biomineralization of Calcium Phosphate as a Strategy to Facilely Synthesize Functionalized Hybrids

Organic-inorganic hybrid materials have been considered to be promising carriers or immobilization matrixes for biomolecules due to their high efficiency and significantly enhanced activities and stabilities of biomolecules. Here, the well-defined dopamine/calcium phosphate organic-inorganic hybrids (DACaPMFs) are fabricated via one-pot dopamine-mediated biomineralization, and their structure and properties are also characterized. Direct stochastic optical reconstruction microscopy (dSTORM) is first used to probe the distribution of organic components in these hybrids. Combined with spectroscopic data, the direct observation of dopamine in the hybrids helps to understand the formation of a physical chemistry mechanism of the biomineralization. The obtained DACaPMFs with multiple-level pores allow the loading of doxorubicin with a high loading efficiency and a pH-responsive property. Furthermore, thrombin is entrapped by the hybrids to prove the controlled release. It is expected that such organic-inorganic hybrid materials may hold great promise for application in drug delivery as well as scaffold materials in bone tissue engineering and hemostatic material.

Understanding intricacies of bioinspired organic-inorganic hybrid nanoflowers: A quest to achieve enhanced biomolecules immobilization for biocatalytic, biosensing and bioremediation applications

The immobilization of biomolecules has been a subject of interest for scientists for a long time. The organic-inorganic hybrid nanoflowers are a new class of nanostructures that act as a host platform for the immobilization of such biomolecules. It provides better practical applicability to these functional biomolecules while also providing superior activity and reusability when catalysis is involved. These nanostructures have a versatile and straightforward synthesis process and also exhibit enzyme mimicking activity in many cases. However, this facile synthesis involves many intricacies that require in-depth analysis to fully attain its potential as an immobilization technique. A complete account of all the factors involving the synthesis process optimisation is essential to be studied to make it commercially viable. This paper explores all the different aspects of hybrid nanoflowers which sets them apart from the conventional immobilization techniques while also giving an overview of its wide range of applications in industries.

Bovine Serum Albumin-Directed Fabrication of Nanohydroxyapatite with Improved Stability and Biocompatibility

Nanohydroxyapatite (nHAp) has gained considerable concerns due to its vast potential in biomedical applications such as drug delivery, tissue engineering and bone repair. However, the preparation of HAp nanostructures in a controllable manner under environment-friendly reaction conditions remains a challenge. In recent years, the use of biological macromolecules or proteins as templates in the production of nanomaterials has gained more attention due to the relatively mild physical conditions needed for biomimetic synthesis. In this study, a novel nHAp was fabricated by employing bovine serum albumin (BSA) as template under mild condition. After that, the as-obtained nanostructured materials which have well-defined structures and morphologies were characterized by various methods. Furthermore, the rod-like shaped hydroxyapatite demonstrated improved stability properties, as well as cell viability and biocompatibility, compared to BSA free synthesized c-HAp. We expect that this pleasantly novel research will render new insights into the fabrication strategies of nanomaterials and be of practical importance for the expanding biological application.

Enzyme-Loaded Flower-Shaped Nanomaterials: A Versatile Platform with Biosensing, Biocatalytic, and Environmental Promise

As a result of their unique structural and multifunctional characteristics, organic-inorganic hybrid nanoflowers (hNFs), a newly developed class of flower-like, well-structured and well-oriented materials has gained significant attention. The structural attributes along with the surface-engineered functional entities of hNFs, e.g., their size, shape, surface orientation, structural integrity, stability under reactive environments, enzyme stabilizing capability, and organic-inorganic ratio, all significantly contribute to and determine their applications. Although hNFs are still in their infancy and in the early stage of robust development, the recent hike in biotechnology at large and nanotechnology in particular is making hNFs a versatile platform for constructing enzyme-loaded/immobilized structures for different applications. For instance, detection- and sensing-based applications, environmental- and sustainability-based applications, and biocatalytic and biotransformation applications are of supreme interest. Considering the above points, herein we reviewed current advances in multifunctional hNFs, with particular emphasis on (1) critical factors, (2) different metal/non-metal-based synthesizing processes (i.e., (i) copper-based hNFs, (ii) calcium-based hNFs, (iii) manganese-based hNFs, (iv) zinc-based hNFs, (v) cobalt-based hNFs, (vi) iron-based hNFs, (vii) multi-metal-based hNFs, and (viii) non-metal-based hNFs), and (3) their applications. Moreover, the interfacial mechanism involved in hNF development is also discussed considering the following three critical points: (1) the combination of metal ions and organic matter, (2) petal formation, and (3) the generation of hNFs. In summary, the literature given herein could be used to engineer hNFs for multipurpose applications in the biosensing, biocatalysis, and other environmental sectors.

Organic-Inorganic Hybrid Nanoflower Production and Analytical Utilization: Fundamental to Cutting-Edge Technologies

Over the past decade, science has experienced a growing rise in nanotechnology with ground-breaking contributions. Through various laborious technologies, nanomaterials with different architectures from 0 D to 3 D have been synthesized. However, the 3 D flower-like organic-inorganic hybrid nanomaterial with the most direct one-pot green synthesis method has attracted widespread attention and instantly become research hotspot since its first allusion in 2012. Mild synthesis procedure, high surface-to-volume ratio, enhanced enzymatic activity and stability are the main factor for its rapid development. However, its lower mechanical strength, difficulties in recovery from the reaction system, lower loading capacity, poor reusability and accessibility of enzymes are fatal, which hinders its wide application in industry. This review first discusses the selection of non-enzymatic biomolecules for the synthesis of hybrid nanoflowers followed by the innovative advancements made in organic-inorganic hybrid nanoflowers to overcome aforementioned issues and to enhance their extensive downstream applications in transduction technologies. Besides, the role of hybrid nanoflower has been successfully utilized in many fields including, water remediation, biocatalyst, pollutant adsorption and decolourization, nanoreactor, biosensing, cellular uptake and others, accompanied with several quantification technologies, such as ELISA, electrochemical, surface plasmon resonance (SPR), colorimetric, and fluorescence were comprehensively reviewed.

Preparation and pore-forming mechanism of hydrogen bond and ionic bond double-driven chitosan-based mesoporous carbon

Using chitosan as the carbon source, F127 as the template, and sodium tripolyphosphate as cross-linking agent, a hydrogen bond and ionic bond double-driven mesoporous carbon material was prepared via the sol-hydrothermal method and its formation mechanism was discussed. According to the results from FTIR, Raman, XPS, physical adsorption analyzer, SEM, TEM, and TG-IR, the mesoporous carbon material was formed under the synergistic effect of hydrogen bond and ionic bond has a mesoporous volume of 0.44 cm³/g, a BET surface area of 262 m²/g, and possesses the ideal unimodal distribution around 2.20 nm. The mesopores are originated from the degradation of hydrophobic segment PPO of F127, and the micropores come from the gases CO₂, CO, NH₃, CH₄, tetraethylene glycol dimethyl ether, and 2,6-diisopropylphenyl isocyanate produced during the degradation of prepolymers. The maximum adsorption capacity of this mesoporous carbon for tannic acid (Sips model) at 30 °C is 70.4 mg/g.

Protein morphology drives the structure and catalytic activity of bio-inorganic hybrids

Bio-hybrid materials have received a lot of attention in view of their bio-mimicking nature. One such biomimetic material with catalytic activity are the protein derived floral nanohybrid. Copper phosphate coordinated flakes can be curated to distinct floral morphology using proteins. Structurally two different proteins with similar size and with no known enzymatic activity are used to evaluate the role of protein structure and morphology, on the structure-activity relationship of the developed hybrid nanoflowers. Globular protein BSA and bacterial microcompartment domain protein PduBB' are selected. PduBB' because of self-assembling nature forms extended sheets, whereas BSA lacks specific assembly. The developed hybrid NFs differ in their morphology and also in their mimicry as a biological catalyst. The present investigation highlights the importance of the quaternary structure of proteins in tailoring the structure and function of the h-NFs. The results in this manuscript will motivate and guide designing, engineering and selection of glue material for fabricating biomacromolecule derived biohybrid material to mimic natural enzymes of potential industrial application.

Chitosan based-nanoparticles and nanocapsules: Overview, physicochemical features, applications of a nanofibrous scaffold, and bioprinting

Recent advancements in the synthesis, properties, and applications of chitosan as the second after cellulose available biopolymer in nature were discussed in this review. A general overview of processing and production procedures from A to Z was highlighted. Chitosan exists in three polymorphic forms which differ in degree of crystallinity (α, β, and γ). Thus, the degree of deacetylation, crystallinity, surface area, and molecular mass significantly affect most applications. Otherwise, the synthesis of chitosan nanofibers is suffering from many drawbacks that were recently treated by co-electrospun with other polymers such as polyvinyl alcohol (PVA), polyethylene oxide (PEO), and polycaprolactone (PCL). Ultimately, this review focuses on the area of new trend utilization of chitosan nanoparticles as nanospheres and nanocapsules, in cartilage and bone regenerative medicine. Owing to its biocompatibility, bioavailability, biodegradability, and costless synthesis, chitosan is a promising biopolymeric structure for water remediation, drug delivery, antimicrobials, and tissue engineering.

Hemoglobin–metal2+ phosphate nanoflowers with enhanced peroxidase-like activities and their performance in the visual detection of hydrogen peroxide

Hemoglobin (Hgb)–metal²⁺ phosphate nanoflowers (Hgb–X²⁺-Nfs) were synthesized using Co²⁺, Zn²⁺, Ca²⁺, and Fe²⁺ separately as inorganic components, to generate a visual hydrogen peroxide (H₂O₂) biosensor for the first time.

Tunable Microstructure and Morphology of the Self-Assembly Hydroxyapatite Coatings on ZK60 Magnesium Alloy Substrates Using Hydrothermal Methods

Hydroxyapatite coatings have been widely used to improve the corrosion resistance of biodegradable magnesium alloys. In this paper, in order to manufacture the ideal hydroxyapatite (HA) coating on the ZK60 magnesium substrate by hydrothermal method, formation mechanism of enhanced hydroxyapatite (HA) coatings, influence of pH values of the precursor solution on the HA morphology, corrosion resistance and cytotoxicity of HA coatings have been investigated. Results show that the growth pattern of the HA is influenced by the local pH value. HA has a preferential c-axis and higher crystallinity in the alkaline environment developing a nanorod-like structure, while in acid and neutral environments it has a preferential growth along the a(b)-plane with a lower crystallinity, developing a nanosheet-like structure. The different morphology and microstructure lead to different degradation behavior and performance of HA coatings. Immersion and electrochemical tests show that the neutral environment promote formation of HA coatings with high corrosion resistance. The cell culture experiments confirm that the enhanced corrosion resistance assure the biocompatibility of the substrate-coating system. In general, the HA coating prepared in neutral environment shows great potential in surface modification of magnesium alloys.

Flower-Like Superstructures: Structural Features, Applications and Future Perspectives

Mimicking natural objects such as flowers, is an objective of scientists not only because of their attractive appearance, but also to understand the natural phenomena that underpin real world applications such as drug delivery, enzymatic reactions, electronics, and catalysis, to name few. This article reviews the types, preparation methods, and structural features of flower-like structures along with their key applications in various fields. We discuss the various types of flower-like structures composed of inorganic, organic-inorganic hybrid, inorganic-protein, inorganic-enzyme and organic compositions. We also discuss recent development in flower-like structures prepared by self-assembly approaches. Finally, we conclude our review with the future prospects of flower-like micro-structures in key fields, being biomedicine, sensing and catalysis.

Polyaniline Nanoskein: Synthetic Method, Characterization, and Redox Sensing

Polyaniline nanoskein (PANS), which have polyaniline nanofibers, was developed. PANS was formulated via sequential extracting, heating, and swelling processes. The compositions of PANS have been analyzed using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and Brunauer-Emmett-Teller analysis, and the results of which indicate that PANS is composed of solely organic materials. Moreover, PANS has been shown convertible absorbance characteristics according to surrounding acidic environments, and using these characteristics, the possibility of PANS for sensing of surrounding redox state changes is presented.

Paper-based biosensor based on phenylalnine ammonia lyase hybrid nanoflowers for urinary phenylalanine measurement

The Phenylketonuria (PKU) is an inborn defect of phenylalanine (Phe) metabolism, in which Phe accumulated in the blood causing alterations at the central nervous system. Therefore, the detection of PKU is very important for the early diagnosis of PKU patients. However, existing tests for PKU are time-consuming and require high-resource laboratories. In this study, a novel paper-based biosensor based on phenylalnine ammonia lyase (PAL) hybrid nanoflowers was constructed that provides a semi-quantitative output of the concentration of Phe from urine samples. PAL@Ca₃(PO₄)₂ hybrid nanoflowers (PAL@NF) were first prepared using PAL and Ca²⁺. Synthesis conditions of the PAL@NF on the formation of the PAL@NF were optimized. The PAL@NF exhibited 90% activity recovery under optimal condition. Compared with free PAL, the PAL@NF displayed good storage stability and increased tolerance to proteolysis. After five consecutive operating cycles, the PAL@NF still retained 73% of its initial activity, indicating excellent reusability. Furthermore, the paper-based biosensor was able to detect Phe concentration in urine samples, and exhibited good linearity to the Phe concentrations in the range from 60 to 2400 μM and the response time was only about 10 min. Therefore, the paper-based biosensor can be a promising candidate as a biosensor for the detection of PKU.

Immobilization and Stabilization of Enzyme in Biomineralized Calcium Carbonate Microspheres

Biomineralized uniform and well-organized calcium carbonate microspheres were synthesized for enzyme immobilization, and the immobilized enzyme was successfully stabilized. The physicochemical parameters of calcium carbonate were studied using scanning electron microscopy with energy-dispersive X-ray spectroscopy, particle size analysis, X-ray diffraction analysis, Fourier-transform infrared spectroscopy, and surface area measurement. Additionally, Barrett-Joyner-Halenda adsorption/desorption analysis showed that the calcium carbonate microspheres provided efficient mesopore space for enzyme loading. As a model enzyme, carboxyl esterase (CE) was entrapped and then cross-linked to form an enzyme structure. In this aggregate, the cross-linked enzymes cannot leach out from mesopores, resulting in enzyme stability. The hydrolytic activities of the free and cross-linked enzymes were analyzed over broad temperature and pH ranges. The cross-linked enzyme displayed better activity than the free enzyme. Furthermore, the immobilized CE was found to be stable for more than 30 days, preserving 60% of its initial activity even after being reused more than 10 times. This report is expected to be the first demonstration of a stabilized cross-linked enzyme system in calcium carbonate microspheres, which can be applied in enzyme catalyzed reactions involved in bioprocessing, bioremediation, and bioconversion.

Synthesis, Characterization and Process Optimization of Bone Whitlockite

Whitlockite, being the second most abundant bio-mineral in living bone, finds huge applications in tissue regeneration and implants and its synthesis into its pure form has remained a challenge. Although precipitation of whitlockite phase has been reported recently in many publications, effects of various parameters to control such phase as well as conditions for the bulk preparation of this extremely important bio-mineral have not been investigated so far. In this work, we report the precipitation of pure whitlockite phase using common precursors. As reported in the literature, whitlockite is stable in a narrow pH range, therefore; optimization of pH for the stabilization of whitlockite phase has been investigated. Additionally, in order to narrow down the optimum conditions for the whitlockite precipitation, effect of temperature and heating conditions has also been studied. The obtained solids were characterized using powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). From PXRD analysis, it was observed that heating the precursor's mixture at 100 °C with subsequent aging at the optimized pH resulted in the precipitation of pure whitlockite phase. These results were further confirmed by TGA, SEM and Raman spectroscopy analysis and it was confirmed that the conditions reported here favor whitlockite precipitation without formation of any secondary phase. These reaction conditions were further confirmed by changing all the parameters like aging, heating time, feed rate of precursors one by one. From PXRD analysis of these samples, it was concluded that not only pH but temperature, heating time, aging time and feed rate effect simultaneously on the precipitation of pure whitlockite phase and a subtle change in any of these parameters could lead to the formation of undesired stable secondary calcium phosphate phases.

Upgrading of marine (fish and crustaceans) biowaste for high added-value molecules and bio(nano)-materials

Currently, the Earth is subjected to environmental pressure of unprecedented proportions in the history of mankind. The inexorable growth of the global population and the establishment of large urban areas with increasingly higher expectations regarding the quality of life are issues demanding radically new strategies aimed to change the current model, which is still mostly based on linear economy approaches and fossil resources towards innovative standards, where both energy and daily use products and materials should be of renewable origin and 'made to be made again'. These concepts have inspired the circular economy vision, which redefines growth through the continuous valorisation of waste generated by any production or activity in a virtuous cycle. This not only has a positive impact on the environment, but builds long-term resilience, generating business, new technologies, livelihoods and jobs. In this scenario, among the discards of anthropogenic activities, biodegradable waste represents one of the largest and highly heterogeneous portions, which includes garden and park waste, food processing and kitchen waste from households, restaurants, caterers and retail premises, and food plants, domestic and sewage waste, manure, food waste, and residues from forestry, agriculture and fisheries. Thus, this review specifically aims to survey the processes and technologies for the recovery of fish waste and its sustainable conversion to high added-value molecules and bio(nano)materials.