Covalent organic frameworks: Pioneering remediation solutions for organic pollutants.

Covalent Organic Frameworks (COFs) have emerged as a promising class of crystalline porous materials with customizable structures, high surface areas, and tunable functionalities. Their unique properties make them attractive candidates for addressing environmental contamination caused by pharmaceuticals, pesticides, industrial chemicals, persistent organic pollutants (POPs), and endocrine disruptors (EDCs). This review article provides a comprehensive overview of recent advancements and applications of COFs in removing and remedying various environmental contaminants. We delve into the synthesis, properties, and performance of COFs and their potential limitations and future prospects.

A high valence binary metal-organic framework as an electrode material for aqueous asymmetric supercapacitors.

This study presents the chemical transformation of nickel-based metal-organic frameworks into binary metal-organic frameworks by introducing cobalt metal ions. The resulting NiCo-BDC hierarchical nanostructure exhibited higher oxidation states, resulting in an impressive capacitance of 1431 F g-1. Additionally, the device based on this material exhibited exceptional capacity retention over 3000 cycles.

Hydrothermal integration of MoO2-MoS2@rGO nanoframe networks: A promising approach for efficient bacterial disinfection in wastewater.

The efficient disinfection of bacterial contaminants in wastewater is a critical challenge in the field of environmental remediation. Herein, we present a novel approach for efficient bacterial disinfection using hydrothermally integrated MoO2-MoS2@rGO nanoframe networks. The developed nanoframe networks exhibit a unique architecture comprising of molybdenum dioxide (MoO2) and molybdenum disulfide (MoS2) impregnated on algae biomass reduced graphene oxide (rGO). The as-synthesized nanoframe networks demonstrate exceptional antibacterial activity against Escherichia coli bacteria. The disinfection efficiency was evaluated by measuring the bacterial viability and observing the morphological changes using scanning electron microscopy. The MoO2-MoS2@rGO nanoframe networks exhibited a remarkable antibacterial effect, achieving a high disinfection rate of 95.8% within a short contact time of 10 min. The efficient bacterial disinfection capability of the nanoframe networks can be attributed to the synergistic effects of MoO2, MoS2, and rGO components. The MoO2 nanoparticles generate reactive oxygen species (ROS), persuading oxidative stress and leading to bacterial inactivation. The MoS2 nanoparticles possess inherent antibacterial properties through the release of Mo and S ions. The rGO nanosheets provide a conductive and stable platform, facilitating the charge transfer during the antibacterial process. Furthermore, the hydrothermal integration method enables easy scalability and cost-effectiveness of the MoO2-MoS2@rGO nanoframe networks. The nanoframe networks can be easily recovered and reused, reducing waste generation and promoting sustainability. Overall, this study presents a promising approach for efficient bacterial disinfection in wastewater using hydrothermally integrated MoO2-MoS2@rGO nanoframe networks. The remarkable antibacterial performance, along with the advantages of scalability and reusability, makes these nanoframe networks a potential candidate for practical applications in environmental remediation and water treatment processes.

Scalable approach to fabricate paper-based biomass reduced graphene sensor for the detection of exhaled diabetic breath.

Herein, we demonstrate a microwave-assisted chemical reduction technique to exfoliate a few layers of graphene from the natural waste material, 'coconut shell'. The microwave irradiation coconut shell is subjected to structural, morphological and functional groups characterization methods including SEM, Raman, FTIR and XPS spectroscopic analyses. The formation of biomass reduced graphene (BRG) has been confirmed through Raman and FTIR spectroscopic analyzes with the presence of D, G and 2D and other functional spectral bands, respectively. The surface topography of the BRG exhibits two-dimensional mat structures with wrinkle topography, imaged by electron microscopic techniques. The metallic behaviour of the BRG is evaluated by band structure calculation using density functional theory. The synthesized nanostructure has been evaluated for exhaled diabetic breath sensing application by fabricating sensor device on the paper-based substrate by roll-to-roll coating technique. The BRG sensor exhibited enhanced sensing response at a very lower concentration of diabetic biomarker with long term stability and rapid response/recovery time of 1.11 s/41.25 s, respectively. Based on our findings, the microwave-assisted BRG is a potential candidate for fabricating highly scalable, inherently safe, economically viable and excellent sensing performance to detect exhaled diabetic breath at room temperature.

Drug infused Al2O3-bioactive glass coatings toward the cure of orthopedic infection.

A unique implant coated substrate with dual-drug-eluting system exhibiting antibacterial, anti-inflammatory, and bone regenerative capacity has been fabricated using spray pyrolysis deposition (SPD) method. Bioglass (BG) and BG-alumina (BG-Al) composites coatings with different concentrations of Al incorporated on BG network over the Cp-Ti substrate were fabricated using SPD technique. Phase purity of BG and BG-Al composites were analyzed by XRD in which Na2Ca2Si3O9 and ß-Na2Ca4(PO4)2SiO4) and Na7.15(Al7.2Si8.8O32) phases were formed. Surface morphology of the coated substrates was analyzed by SEM. Uniformity of the coatings were evaluated by surface profilometer and the uniform distribution the nanoparticles were confirmed with Elemental mapping. Systematically, each apatite layer formation on coated substrate was confirmed by immersing the samples for 1, 3, and 7 days in simulated body fluid and the needle-like structure was characterized using SEM. Cumulative release of Tetracycline hydrochloride (Tet) antibiotic and Dexamethasone (Dex) anti-inflammatory drug-loaded BG-Al and BG-Al composite-coated substrate were studied for 24 h. Antibacterial activity of the coated substrates were evaluated by time-dependent growth inhibition and minimal inhibitory concentration (MIC) assays in which BG-Al and BG-Al composite loaded with Tet showed considerable growth inhibition against S. aureus. Osteoblast-like cells (MG-63) exhibited profound proliferation with no cytotoxic effects which was due to release of Dex drug-coated substrates. Thus, surface modification of Cp-Ti substrate with BG, BG-Al composites coatings loaded with Tet and Dex drug can be considered for post-operative orthopedic implant infection application.

Visible light driven exotic p (CuO) - n (TiO2) heterojunction for the photodegradation of 4-chlorophenol and antibacterial activity.

The treatment of industrial waste and harmful bacteria is an important topic due to the release of toxins from the industrial pollutants that damage the water resources. These harmful sources frighten the life of every organism which was later developed as the carcinogenic and mutagenic agents. Therefore, the current study focuses on the breakdown or degradation of 4-chlorophenol and the antibacterial activity against Escherichia coli (E. coli). As a well-known catalyst, pure titanium-di-oxide (TiO2) had not shown the photocatalytic activity in the visible light region. Hence, band position of TiO2 need to be shifted to bring out the absorption in the visible light region. For this purpose, the n-type TiO2 nanocrystalline material's band gap got varied by adding different ratios of p-type CuO. The result had appeared in the formation of p (CuO) - n (TiO2) junction synthesized from sol-gel followed by chemical precipitation methods. The optical band gap value was determined by Kubelka-Munk (K-M) plot through UV-Vis diffusive reflectance spectroscopy (DRS). Further, the comprehensive mechanism and the results of photocatalytic and antibacterial activities were discussed in detail. These investigations are made for tuning the TiO2 catalyst towards improving or eliminating the existing various environmental damages.

Photocatalytic degradation of 2,4-dichlorophenol using bio-green assisted TiO2-CeO2 nanocomposite system.

In recent times, cost effective synthesis of semiconductor materials has been a subject of concern for the day to today applications. In this work, novelty has been made on the facile synthesis of metal oxides (TiO2 and CeO2) and nanocomposites (TiO2-CeO2) through sol-gel and precipitation methods of imparting lemon extract. The synthesized materials behave as the functional catalysts which has been further carried out for the photocatalytic degradation against 2,4-Dichlorophenol (2,4-DCP). The materials are then valued for the structural and optical properties. The lemon extract used in synthesis has played a premier role in upgrading the charge carrier separation, bandgap, and size reduction of the composite system. Further, the CeO2 supported TiO2 sample acts as the better visible light catalyst, due to the prevention of aggregation and existence of line dislocation that supported to access the additional electron trap sites.

Plant-derived silica nanoparticles and composites for biosensors, bioimaging, drug delivery and supercapacitors: a review.

Silica nanoparticles have rapidly found applications in medicine, supercapacitors, batteries, optical fibers and concrete materials, because silica nanoparticles have tunable physical, chemical, optical and mechanical properties. In most applications, high-purity silica comes from synthetic organic precursors, yet this approach could be costly, polluting and non-biocompatible. Alternatively, natural silica sources from biomass are often cheap and abundant, yet they contain impurities. Silica can be extracted from corn cob, coffee husk, rice husk, sugarcane bagasse and wheat husk wastes, which are often disposed of in rivers, lands and ponds. These wastes can be used to prepare homogenous silica nanoparticles. Here we review properties, preparation and applications of silica nanoparticles. Preparation includes chemical and biomass methods. Applications include biosensors, bioimaging, drug delivery and supercapacitors. In particular, to fight the COVID-19 pandemic, recent research has shown that silver nanocluster/silica deposited on a mask reduces SARS-Cov-2 infectivity to zero.

Bioactive, degradable and multi-functional three-dimensional membranous scaffolds of bioglass and alginate composites for tissue regenerative applications.

With a worldwide increase in the aged populace and associated geriatric diseases, there is an enormous need for the regeneration of degenerated organ systems. For this purpose, bioactive glass particulate (nBG) integrated alginate (Alg) composite membrane scaffolds were fabricated by a sol-gel assisted freeze-drying method and validated for their multifunctional utility in regenerative medicine. The presence of the combeite highly crystalline structure of nBG and Alg amorphous broad peaks were confirmed. Repetitive peaks from acids along with stretching confirmed the chemical interactions of the composites. Swelling ability, porosity, and in vitro degradation and biomineralization were analysed for up to 7 days. The results indicated that reduced swelling and degradation enhanced apatite formation. Hemocompatibility and the hemostatic properties on scaffolds were also systematically investigated. Additionally, significant cyto-compatibility and proliferation were noted in a culture with KB3-1. Further 3-D co-cultures with HDF cells and KB3-1 cells exhibited spheroid formation on Alg, nBG/Alg and nBG-Zr/Alg with profound dynamism required to establish organoids of interest. Thus, the results indicate that these 3D hydrogel membranes could offer infinite possibilities in the field of regenerative medicine, notably as an extracellular matrix (ECM) supporting the regeneration of bone, intra-vascularization, and neo-tissue formation, such as cartilage and ligaments.

Facile synthesis of paper based graphene electrodes for point of care devices: A double stranded DNA (dsDNA) biosensor.

The demand for high-quality graphene for electronic applications is increasing due to its high carrier mobility and electrical conductivity. In this connection, printing technology is a reliable method towards the fabrication of conductive, disposable graphene-based electrode for low-cost sensor application. Herein, we aimed to report the synthesis of high-quality graphene nanosheets obtained by electrochemical exfoliation of biomass-derived from corn cob. The conductive ink was prepared from this exfoliated graphene and was utilized for the preparation of paper-based graphene electrode towards double stranded DNA (dsDNA) sensor application. This paper, based graphene electrode opens the possibility of direct electrochemical analysis of analyte without any sample preparation. In this study, two irreversible oxide peaks were obtained from paper-based printed graphene electrode, corresponds to oxidation of guanine (G) and adenine (A) of dsDNA in the linear range of 0.2 pg mL-1 to 5 pg mL-1 with the detection limit of 0.68 pg mL-1 and the sensitivity of 0.00656 mA pg-1 cm-2. Further, a small-scale printable circuit is fabricated using this graphene shows good conductivity of 1.145x103(S/m).

Highly reactive crystalline-phase-embedded strontium-bioactive nanorods for multimodal bioactive applications.

In the present work, a crystallization-induced strontium-bioactive material, with a composition similar to Bioglass 45S5 system, was obtained using a sol-gel-assisted microwave method with nanorod morphologies of 30-80 nm in size. The effect of crystallization induced in the glass network, and its influence on the bioactivity and mechanical properties of bone and dentin regeneration, were the main novel findings of this work. Rietveld analysis of X-ray diffraction spectra showed the best fit with sodium (combeite, Na2Ca2Si3O9) and calcium (clinophosinaite, Ca2Na6O14P2Si2; calcium strontium silicate, Ca1.5O4SiSr0.5; and calcium carbonate, CaCO3) enriched crystal systems. Multinuclear solid-state NMR studies provided detailed atomistic insight into the presence of crystalline mineral phases in the bioactive material. The dentin matrix and antibacterial studies showed good results for 5% strontium-substituted calcium compared with basic 45S5 composition due to its smaller particle size (30 nm), which suggested applications to dentin regeneration. Simulation studies have been demonstrated with clinophosinaite crystal data from the XRD spectra, with the glycoprotein salivary metabolites also showing that 5% strontium-substituted calcium has a higher binding affinity for the salivary compound, which is suitable for dentin regeneration applications. In vitro apatite formation studies showed that this material is suitable for bone regeneration applications.

Effect of Titania Concentration in Bioglass/TiO2 Nanostructures and Its In Vitro Biological Property Assessment.

Bioglass 45S5 (45% SiO2-24.5% NaO-24.5% CaO-6% P2O5) is a unique bioactive material, which is being used for bone and dental substitution. This system has been highly preferred for its osteoconductive and osteoinductive performance. Despite its attractive bioactivity, there are limitations in using this material for orthopedic and dental applications due to its poor processability and mechanical strength. To improve the load-sharing and stress distribution, TiO2 nanoparticles have been introduced into the nanoBioglass (nBG) by sol-gel method. The structural analyses of the samples were confirmed using X-ray diffraction, Raman-spectroscopy and FTIR. The morphologies of the samples were characterized by FESEM. The apatite formation of the nBG/TiO2 composites was investigated by immersing the samples in simulated body Fluid (SBF) solution for 1 and 3 days, which reveals the acceptable compatibility for different concentrations of all the composition. Hemolysis studies of the nanobiomaterials were carried out to understand the interactions of biomaterials with blood which shows 0.2%-2% of lysis which is acceptable as per ASTM standard. Cell culture and cell proliferation studies of bioglass, nBG/TiO2 nanocomposite on MG-63 pre-osteoblast cell line for 24 h, 48 h and 72 h showed 80% to 95% of cell viability. Also, it was found that the nBG/TiO2 bio-nanocomposites containing low content of titania had good bioactivity properties that is comparable to cortical bone. Hence, nBG/TiO2 bio-nanocomposites are greatly promising for medical applications such as bone substitutes especially in load-bearing sites.

Structural, Morphological and Antibacterial Investigation of Ag-Impregnated Sol-Gel-Derived 45S5 NanoBioglass Systems.

An increasing percentage of ageing population requires 30-year survivability of orthopedic devices that is not possible with the current bioinert materials, having a maximum of 15-year survivability. To satisfy this growing need, a shift is needed from replacement of tissues to regeneration of tissues. This is highly possible through the use of silica-bioactive glasses. However, a failure of implant can occur due to infections even by using such materials. Advances in using silver for antibacterial applications have been commercialized. However, higher concentrations of silver also lead to toxic effects. In this study, nanoBioglass 45S5 (NBG) and Ag-NBG were synthesized by using sol-gel method followed by solution-phase method, respectively. The bioactive crystals such as Na2Ca2Si3O9, CaCO3, and AgPO3, very much needed in the field of bone tissue engineering and in antibacterial strategies, were obtained in the NBG Matrix. The morphological investigation of NBG with 1 mM Ag+ concentrations shows the nanospikes arrangement of size 30-40 nm with spherical porous structure of size 10-20 nm, which supports the formation of collagen molecular fibrils on the surface of NBG matrices and enhances osseointegration. Both gram-positive and gram-negative strains show higher antibacterial activity for nanoBioglass with 1 mM Ag+ concentration.

Phase separation induced shell thickness variations in electrospun hollow Bioglass 45S5 fiber mats for drug delivery applications.

In the present study, sub-micron sized hollow Bioglass 45S5 nanofibers are synthesised using an electrospinning technique with the assistance of polyvinyl pyrrolidone. The electrospinning process parameters are optimized to obtain reproducible nanofibers. The effects of solvent and polymer concentrations on the morphology and formation of fibers are studied. Ethanol and water are used to vary the concentration and it is observed that an increase in dilution by water decreases the shell thickness of the hollow fibers. The mechanism of the formation of the hollow fibers is attributed to phase separation, which occurs during physical cooling of the fibers. Fibers prepared from a solution diluted with an equal ratio of ethanol and water show a higher performance in drug loading and releasing kinetics due to their narrow and linear size distribution. These fibers are also highly suitable for bone tissue engineering applications due to their linear fibrous 3D structural mat architecture and they are suitable for large size scaling.

Analysis of solvent induced porous PMMA-Bioglass monoliths by the phase separation method--mechanical and in vitro biocompatible studies.

Mimicking three dimensional microstructural scaffolds with their requisite mechanical properties in relation to human bone is highly needed for implant applications. Various biocompatible polymers and bioactive glasses were synthesized to achieve these properties. In the present study, we have fabricated highly porous and bioactive PMMA-Bioglass scaffolds by the phase separation method. Chloroform, acetone and an ethanol-water mixture were used as the different solvent phases in preparing the scaffolds. Large interconnecting pores of sizes ∼100 to 250 µm were observed in the scaffolds and a porosity percentage up to 54% was also achieved by this method. All samples showed a brittle fracture with the highest modulus of 91 MPa for the ethanol-water prepared scaffolds. The bioactivities of the scaffolds were further studied by immersing them in simulated body fluid for 28 days. Scanning electron microscopy, X-ray diffraction and Raman spectra confirmed the formation of bioactive hydroxyl calcium apatite on the surfaces of the scaffolds.