Organic-inorganic Hybrid Nanoflowers Research Articles

Multifarious Chiral Nanoarchitectures Serving as Handed-Selective Fluorescence Filters for Generating Full-Color Circularly Polarized Luminescence.

A series of full-color circularly polarized luminescence (CPL)-active materials are fabricated by judiciously combining multifarious chiral nanoarchitectures with achiral fluorescence dyes. The investigated nanoarchitectures include organic polymer nanofibers, organic-inorganic hybrid nanoflowers, and inorganic nanoflowers. The as-prepared chiral nanoarchitectures all can act as handed-selective fluorescence filters to powerfully transform unpolarized fluorescent light into circularly polarized luminescence. Also notable, no interaction is required between chiral and fluorescent components for achieving CPL emission. The present study provides a convenient and universal approach for preparing full-color CPL materials. Following the strategy, numerous chiroptical materials with CPL performance can be expected due to the abundant chiral matters and achiral fluorophores.

Hybrid nanoflowers bearing tetraphenylporphyrin assembled on copper(II) or cobalt(II) inorganic material: A green efficient catalyst for hydrogenation of nitrobenzenes in water

Simple fabrication of organic–inorganic hybrid nanoflowers (TPP@CuhNfs and TPP@CohNfs) was achieved with tetraphenylporphyrin (TPP) as organic counterpart and Cu2+ or Co2+ ions as inorganic materials via a green route, with lower cost and controlled pH. The effect of pH levels and TPP concentrations on the morphology of the TPP@CuhNfs and TPP@CohNfs materials was examined by scanning electron microscopy (energy‐dispersive X‐ray [EDX]). The formation and chemical structures of TPP@CuhNfs and TPP@CohNfs were evaluated using Fourier transform infrared. Elemental analyses of these hybrid nanoflowers were carried out by EDX. The fabricated TPP@CuhNfs and TPP@CohNfs nanomaterials under optimum conditions act as effective reusable catalysts for the hydrogenation of nitroanilines in aqueous media at ambient temperature. The time‐dependent hydrogenation can be easily monitored spectrophotometrically and verified by 1H‐nuclear magnetic resonance. These types of the catalytic reaction or system are recorded to be useful toward the hydrogenation of nitroanilines, regardless of the position and type of substrate. Moreover, TPP@CuhNfs and TPP@CohNfs catalysts demonstrated a type of metal ions‐dependent catalytic efficiency toward hydrogenation of nitroanilines (organic pollutants), with TPP@CuhNfs found to be more effective than TPP@CohNfs. However, both catalysts containing Cu2+ and Co2+ ions showed good performance and can be reused at least five times without a significant decline in yield. The presented approach based on hybrid nanoflowers provides as a low cost and ecofriendly method (green route) for different catalytic hydrogenations.

Dual-enzyme and NADPH co-embedded organic–inorganic hybrid nanoflowers prepared using biomimetic mineralization for the asymmetric synthesis of (R)-(−)-pantolactone

A SA-coated hNF composite was designed to co-immobilize dual enzymes and coenzyme NADP+ for the asymmetric synthesis of d-(−)-pantolactone.

Synthesis of organic-inorganic hybrid nanoflowers using Trigonella foenum-graecum seed extract and investigation of their anti-microbial activity

Herein we report a green method for the synthesis of organic-inorganic hybrid nanoflowers using a Trigonella foenum-graecum L. (TF) (Fenugreek seeds) extracts as an organic part and copper ions acting as an inorganic part. The organic-inorganic hybrid nanoflowers using TF seed extract (TF-Cu2+ hNFs) were characterized by SEM, XRD, EDX and FTIR. The morphology of the TF-Cu2+ hNFs was quite spherical and monodisperse with ∼18μm size. The TF-Cu2+ hNF exhibited the effective anti-bacterial activity against Enterococcus faecium, Enterococcus faecalis, Staphylococcus aureus, Bacillus cereus, Salmonella typhi and Escherichia coli at 1-10 µg ml-1 concentrations except against Pseudomonas aeruginosa and Haemophilus influenza. However, both TF-Cu2+ hNFs and free TF extracts showed any antifungal activities against Candida albicans or Candida glabrata. The study revealed that TF-Cu2+ hNFs could be used as a therapeutic agent for microbial infections and has the potential to overcome drug resistance.

Cu-nanoflower decorated gold nanoparticles-graphene oxide nanofiber as electrochemical biosensor for glucose detection.

A novel electrospinning approach is proposed for the fabrication of copper (Cu)-nanoflower decorated gold nanoparticles (AuNPs)-graphene oxide (GO) nanofiber (NF) as an electrochemical biosensor for the glucose detection. In this study, GO was mixed with poly(vinyl alcohol) (PVA) and used as a fiber precursor, which greatly improves the electrochemical properties. The above solution was uniformly coated onto the surfaces of gold chip to form GO NFs via electrospinning. AuNPs were coated onto the surface of GO NFs and then incorporated organic-inorganic hybrid nanoflower [Cu nanoflower-glucose oxidase (GOx) and horseradish peroxidase (HRP)]. The electrochemical experiments revealed that Cu-nanoflower@AuNPs-GO NFs exhibited outstanding electrochemical catalytic nature, and selectivity for the conversion of glucose to gluconic acid in the presence of GOx-HRP-Cu nanoflower. The Cu-nanoflower@AuNPs-GO NFs coated Au chip exhibited good linear range 0.001-0.1 mM, with a detection limit of 0.018 μM. The Cu-nanoflower@AuNPs-GO NFs modified Au chip exhibited higher catalytic properties, which are attributed to the coating of unique organic-inorganic nanostructured materials on the surfaces of Au chip. These results indicate that the nano-bio hybrid materials can be applied as a promising electrochemical biosensor to monitor glucose levels in biofluids.

Hybride metall-organic nanoflowers and their applications in biotechnology

Among the variety of modern nanomaterials a special class – nanoflowers can be distinguished. These new nanostructures have induced the interest of scientists due to the topographic features of nanolayers, the special location of which allows a higher surface-to-volume ratio compared to classical spherical nanoparticles. Such topographic structure significantly increases the efficiency of surface reactions for nanoflowers. The main purpose of this type of nanomaterials is their use as enzyme stabilizers. Enzymes are biosystems with high activity and substrate specificity, but their use is limited by certain disadvantages, such as high sensitivity to the environment, low reproducibility of experimental results and requirements for complex purification of the components. To facilitate the functioning of enzymes in various conditions, organicinorganic hybrid nanomaterials have been developed, the name of which indicates that all components of inorganic nanoparticles are associated with organic materials. These nanoparticles have numerous promising applications in catalysis, as biosensors, and for drug delivery. Organic-inorganic hybrid nanoflowers have led to the development of a new branch of chemistry – the chemistry of hybrid nanomaterials, whose research is currently undergoing rapid development. Thus, the study of organic-inorganic hybrid nanocrystals can lead to new creative solutions in the field of chemistry of enzyme systems and the rapid development of bionanomaterials and new branches of biotechnology.

A sandwich-type electrochemical aptasensor for the carcinoembryonic antigen via biocatalytic precipitation amplification and by using gold nanoparticle composites.

A sandwich-type electrochemical aptasensor is described for detecting the carcinoembryonic antigen (CEA) with high sensitivity and accuracy. Two kinds of nanomaterials are used. The first was obtained by modifying gold nanoparticles with reduced graphene oxide and hemin (Hemin-rGO-AuNPs). The second consists of horseradish peroxidase-modified organic-inorganic hybrid nanoflowers linked to gold nanoparticles to obtain an architecture of type HRP-Cu3(PO4)2-HNF-AuNPs). These serve as carriers for two aptamers (apt1 and apt2) against CEA. Simultaneously, they were used to catalyze the precipitation reaction between 4-chloro-1-naphthol(4-CN) and H2O2. A sandwich-type assay linked to enzyme inhibition amplification was established for electrochemical determination of CEA. Under optimal experimental conditions and by using differential pulse voltammetry, the response peak currents (best measured at -0.34V vs. Ag/AgCl) increases linearly with the logarithm of the CEA concentration in the range between 100fgmL-1 and 100ngmL-1. The detection limit is as low as 29fgmL-1. Graphical abstract Schematic representation of the sandwich-type electrochemical aptasensor based on signal inhibition amplification from biocatalytic precipitation reaction. (HRP-Cu3(PO4)2 hybrid nanoflowers: Horseradish Peroxidase-Cu3(PO4)2 hybrid nanoflowers; AuNPs: Gold Nanoparticles; Hemin-rGO-AuNPs: Hemin-Reduced Graphene Oxide-Gold Nanoparticles; BSA: Bovine Serum Albumin; CEA: Carcinoembryonic Antigen; CEAapt1: 5'-SH-(CH2)6-ATA CCA GCT TAT TCA ATT-3'; CEAapt2: 5'-NH2-(CH2)6-AGG GGG TGA AGG GAT ACC C-3'; GCE: Glassy carbon electrode; 4-CN: 4-Chloro-1-naphthol; DPV: Differential pulse voltammetry).

Bioinspired synthesis of organic–inorganic hybrid nanoflowers for robust enzyme-free electrochemical immunoassay

Protein-inorganic nanoflowers have been extensively used for sensing and biosensing applications by virtue of the signal enhancement of protein component---enzyme. Can the inorganic component of protein-inorganic nanoflowers be employed to amplify signal transducing for enzyme-free detection? In this work, a new kind of BSA-antibodies-copper phosphate hybrid nanoflowers (BSA-Ab2-Cu3(PO4)2) has been prepared by one-pot biomimetic mineralization process as signal enhancer for enzyme-free electrochemical immunoassay. C-reactive protein (CRP) has been chosen as a model biomarker. To the best of our knowledge, it is the first trial using the inorganic component---phosphate ions of BSA-Ab2-Cu3(PO4)2 for transducing electrochemical readout, which features the following advantages: (1) the three-dimensional hierarchical porous nanoflower morphology with a high specific surface area could load more antibodies, and BSA for blocking non-specific sites, greatly increasing the sensitivity of the fabricated immunosensors, (2) the Cu3(PO4)2 hybrid nanoflowers can supply a huge amount of phosphate anions to react with molybdate yielding molybdophosphate precipitates and generating redox currents for more robust enzyme-free electrochemical signal readout. The fabricated immunosensor has exhibited good detection performance with a linear range of 5 pg/mL–1 ng/mL and a limit of detection of 1.26 pg/mL. Moreover, our method has presented good feasibility for clinical sample analysis.

Organic-inorganic nanoflowers: from design strategy to biomedical applications.

Organic-inorganic hybrid nanoflowers (NF) with sizes or features on a nanoscale are a class of flower-shaped nanomaterials self-assembled from metal ions and organic components. Here, to be more specific, the organic components mainly refer to biomolecules ranging from proteins, peptides, and amino acids to DNA/RNA. Beyond their pleasing aesthetics, their unique properties and integrated functions have attracted widespread interest and made them promising candidates in the application of biomedical areas. Great efforts have been made to design and synthesize versatile functional hybrid nanoflowers. In this review, we begin with the clarification of versatile recently reported hybrid nanoflowers according to the types of metal ions and biomolecules employed. To highlight the design of organic-inorganic hybrid nanoflowers, their synthetic methods and mechanisms, structural and biological characteristics are discussed. After that, the state-of-the-art applications of hybrid nanoflowers in biomedical fields including biosensing, biocatalysis, and cancer therapy are demonstrated. In the end, we discuss the prospects of organic-inorganic hybrid nanoflowers and highlight the challenges and opportunities for future research.

Point-of-care assay to detect foodborne pathogenic bacteria using a low-cost disposable medical infusion extension line as readout and MnO2 nanoflowers

The extended application of low cost disposable infusion extension lines, used primarily in the medical field, is limited. In this study, a facile signal readout method was developed for point-of-care (POC) detection of foodborne pathogenic bacteria using disposable medical infusion extension lines. Herein, organic-inorganic hybrid nanoflowers loaded with sufficient MnO2 have been easily prepared. The MnO2 nanoflowers with pathogenic bacteria recognition function decomposed hydrogen peroxide (H2O2) into oxygen (O2), an amplified gas signal, which was measured by a disposable medical infusion extension line. The generation of O2 from H2O2 by the catalytic dissociation of MnO2 nanoflowers increased the pressure in a confined space. Dye was then pushed along the channel of the disposable medical infusion extension line, connected to a sealed glass vial via a needle. The distance moved by the dye, which was detectable by the naked eye, was proportional to the concentration of foodborne pathogenic bacteria. Experimental results showed detection limits as low as 101 CFU/mL for Salmonella sp. and Escherichia coli O157:H7. The biosensor method based on a low-cost disposable medical infusion extension line gas signal readout was a powerful tool for POC testing of foodborne pathogenic bacteria under resource-limited settings.

Organic-Inorganic Hybrid Nanoflowers as Potent Materials for Biosensing and Biocatalytic Applications

Flower-shaped organic-inorganic hybrid nanostructures, termed nanoflowers, have received considerable recent attention as they possess greatly enhanced activity, stability, durability, and even selectivity of entrapped organic biomolecules, which are much better than those from the conventional methods. They can be synthesized simply via co-incubation of organic and inorganic components in aqueous buffer at room temperature and yield hierarchical nanostructures with large surface-to-volume ratios, allowing for low-cost production by easy scale-up, as well as the high loading capacity of biomolecules without severe mass transfer limitations. Since a pioneering study reported on hybrid nanoflowers prepared with protein and copper sulfate, many other organic and inorganic components, which endow nanoflowers with diverse functionalities, have been employed. Thanks to these features, they have been applied in a diverse range of areas, including biosensors and biocatalysis. To highlight the progress of research on organic-inorganic hybrid nanoflowers, this review discusses their synthetic methods and mechanisms, structural and biological characteristics, as well as recent representative applications. Current challenges and future directions toward the design and development of multi-functional nanoflowers for their widespread utilization in biotechnology are also discussed.

Application of dual-enzyme nanoflower in the epoxidation of alkenes

Abstract In this work, a novel organic-inorganic hybrid nanoflower was synthesized by the incorporation of glucose oxidase and lipase and used as the coimmobilized enzyme in the epoxidation of alkenes. Imaging and catalytic performance results suggest that the dual-enzyme nanoflower greatly reduces the diffusion and decomposition of H 2 O 2 and facilitates the mass transfer of glucose oxidase/lipase. Furthermore, the controllable generation of H 2 O 2 and peracid contributes to the good stability of the dual-enzyme nanoflower, which exhibits a higher catalytic performance than the free enzymes in a dual-enzymatic cascade epoxidation. The yield of epoxidation was up to 82% even after ten cycles, further indicating the good reusability of the dual-enzyme nanoflower and its great potential for application in other enzymatic oxidations.

Convenient Colorimetric Detection of Cholesterol Using Multi-Enzyme Co-Incorporated Organic-Inorganic Hybrid Nanoflowers.

We have developed a microscale well-plate colorimetric assay for the multiplexed detection of cholesterol in clinical human blood samples. This system utilizes a novel multi-enzyme incorporated organic-inorganic hybrid nanoflower which entrap both cholesterol oxidase (ChOx) and horseradish peroxidase (HRP) as the organic components with copper phosphate as the inorganic component to detect cholesterol levels in blood samples. The hybrid nanoflowers, synthesized via an extremely simple but rapid sonication-mediated method within 5 min at room temperature, enable an efficient one-pot two-enzyme cascade reaction. The ChOx in the nanoflowers catalyze the generation of H2O2 only in the presence of cholesterol in the sample. This subsequently activates the HRP co-entrapped in the nanoflowers, thereby leading to the conversion of the employed chromogenic substrate, 3,3',5,5'-tetramethylbenzidine (TMB), into a blue-colored product. This strategy can be used to detect target cholesterol concentrations as low as 8 μM, with a linear range from 10 to 70 μM, which is suitable to diagnose high levels of cholesterol (hypercholesterolemia) with excellent stability over three weeks at room temperature. The biosensor also exhibited an excellent selectivity to detect target cholesterol even in the presence of common interfering biomolecules in human blood and showed a high degree of precision when employing human blood serum samples. Therefore, this hybrid nanoflower-based assay can be used in clinical practice for the multiplexed and reliable quantification of cholesterol, and readily extended to other enzymes to prepare multi-step cascade enzymatic reactions for various biotechnological applications.

유-무기 혼성 나노 꽃의 생물공학적 응용 연구 동향

Organic-inorganic hybrid nanostructures with flower-like morphology, so called nanoflowers, have received an increasing attention due to their capability to greatly enhance the activity, stability, and durability of entrapped biomolecules, which is much better than those from the conventional immobilization strategies. These hybrid nanoflowers are simply synthesized via the incubation at room temperature but show high surface roughness and large surface-tovolume ratio, which enables high loading capacity of biomolecules without severe mass transfer limitation. Based on the advantageous features, they have been applied in the field of biotechnology such as biosensor, biofuel cell, and protein digestion. To highlight the research progress on organic-inorganic hybrid nanoflowers, this review discusses the synthetic methods, structural characteristics, and recent applications of the nanoflowers. Finally, we address the future prospects of the hybrid nanoflowers in biotechnology industry, particularly for sensing, medicine, and catalyst.

Nanoflower-Shaped Biocatalyst with Peroxidase Activity Enhances the Reversible Addition–Fragmentation Chain Transfer Polymerization of Methacrylate Monomers

Organic–inorganic hybrid nanoflowers, facilely made from bovine serum albumin and copper phosphate (BSA–Cu3(PO4)2·3H2O), have attracted considerable attention for the application of biocatalysts in recent years. The improved stability and activity of above-mentioned nanoflowers enhanced the efficiency of reversible addition–fragmentation chain transfer (RAFT) polymerization of functional methacrylate monomers with the assistance of acetylacetone (ACAC) and hydrogen peroxide (H2O2) in a mixed solvent of DMF and H2O. Such RAFT strategy can be employed for the polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA500), in which both poly(DMAEMA) and poly(PEGMA500) could be synthesized in a controllable manner with typical RAFT features, e.g., precise control of molecular weight, specific molecular structure, and narrow polydispersity index (Mw/Mn). Significantly, the low-cost nanoflowers could be easily separated from reaction mixture after p...

Recent advances in biomolecule immobilization based on self-assembly: organic-inorganic hybrid nanoflowers and metal-organic frameworks as novel substrates.

In the past few years, the immobilization of biomolecules on hybrid nanoflowers and metal-organic frameworks (MOFs) via self-assembly synthesis has received much attention due to its simplicity, high efficiency, and a bright prospect of enhancing the stability, activity and even selectivity of biomolecules compared to conventional immobilization methods. In the synthesis of organic-inorganic hybrid nanoflowers, biomolecules used as organic components are simply mixed with metal ions which act as inorganic components to form flower-like nanocomposites, while in the self-assembly process of encapsulating biomolecules in MOFs (biomolecule@MOF composites), the biomolecules just need to be added to the precursor mixtures of MOFs, in which the biomolecules are therefore embedded in MOF crystals with small pores. In this review, we focus on the recent advances of these composites, especially in the synthesis strategies, mechanism and applications in biosensors, biomedicine, pollutant disposal, and industrial biocatalysis, and future perspectives are discussed as well.

Formation of functional nanobiocatalysts with a novel and encouraging immobilization approach and their versatile bioanalytical applications.

The discovery of functional organic–inorganic hybrid nanoflowers (FNFs) consisting of proteins/enzymes as the organic components and Cu(ii) ion as the inorganic component has made an enormous impact on enzyme immobilization studies. The FNFs synthesized by an encouraging and novel approach not only showed high stabilities but also much enhanced catalytic activities as compared to free and conventionally immobilized enzymes. A recent development demonstrated that FNF formation has moved beyond the initial discovery in which enzymes and Cu2+ ions used as the organic and inorganic parts, respectively, are replaced with new organic (chitosan, amino acid and plant extracts) and inorganic (Cu2+ and Fe2+) materials. The new organic materials incorporated into FNFs act as Fenton-like agents and then show peroxidase-like activity owing to the metal ions and the porous structure of FNFs in the presence of hydrogen peroxide (H2O2). All FNFs have been widely utilized in many different scientific and industrial fields due to their greatly enhanced activities and stabilities. This review focuses primarily on the preparation, characterization, and bioanalytical applications of FNFs and explains the mechanisms of their formation and enhanced activities and stabilities.

Egg white hybrid nanoflower (EW-hNF) with biomimetic polyphenol oxidase reactivity: Synthesis, characterization and potential use in decolorization of synthetic dyes

In this study, for the first time, we described organic–inorganic hybrid nanoflowers using crude egg white as the organic component and copper (II) ions as the inorganic component under the mild conditions. The synthesized egg white-inorganic hybrid nanoflowers (EW-hNFs) were characterized using SEM, EDX, XRD and FTIR analysis. The biomimetic Polyphenol/Peroxidase like activities of synthesized egg white-inorganic hybrid nanoflowers (EW-hNFs) were determined by using various phenolics with or without H2O2. Optimum pH and temperature, kinetic parameters, reusability, pH and thermal stability of EW-hNFs were also studied. The most noteworthy aspect of our study is that synthesized EW-hNFs which consist of only egg white proteins, showed polyphenol oxidase activity. Furthermore, potential use of the EW-hNFs in the discoloration of the some synthetic dyes was also evaluated.

A new biosensor based on the recognition of phages and the signal amplification of organic-inorganic hybrid nanoflowers for discriminating and quantitating live pathogenic bacteria in urine

Abstract Rapid and accurate detection of live pathogenic bacteria in urine is indispensable for the diagnosis of urinary tract infection (UTI) in clinical practice. In the present study, an electrochemical biosensor was developed to quantify live bacteria in urine accurately and rapidly, by taking Escherichia coli (E. coli) as an example. The main strategy was based on the specific recognition of T4 phages and the signal amplification of organic-inorganic hybrid nanoflowers (GOx&HRP-Cu3(PO4)2). After connecting the thionine, the signal was gradually amplified with the cascade effect of three redox reactions. Using this proposed electrochemical biosensor, live E. coli can be quantified at a linearity range of 15–1.5 × 108 CFU/mL, with a very low detection limit of 1 CFU/mL. Compared with the traditional method of culturing and counting, the present biosensor is easier and simpler to handle, and the process of quantitation was completed within only 140 min. Present results showed that the proposed electrochemical biosensor has great potential application in diagnosing and monitoring UTI in clinical settings.

A new generation approach in enzyme immobilization: Organic-inorganic hybrid nanoflowers with enhanced catalytic activity and stability.

Many different micro and nano sized materials have been used for enzymes immobilization in order to increase their catalytic activity and stability. Generally, immobilized enzymes with conventional immobilization techniques exhibit improved stability while their activity is lowered compared to free enzymes. Recently, an elegant immobilization approach was discovered in synthesis of flower-like organic-inorganic hybrid nanostructures with extraordinary catalytic activity and stability. In this novel immobilization strategy, proteins (enzymes) and metal ions acted as organic and inorganic components, respectively to form hybrid nanoflowers (hNFs). It is demonstrated that the hNFs highly enhanced catalytic activities and stability in a wide range of experimental conditions (pHs, temperatures and salt concentration, etc.) compared to free and conventionally immobilized enzymes. This review mainly discussed the synthesis, characterization, development and applications of organic-inorganic hybrid nanoflowers formed of various enzymes and metal ions and explained potential mechanism underlying enhanced catalytic activity and stability.