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Herein for the first time, lignocellulose nanofibrils (LCNF) were prepared from pine-wood powder using microwave (MW)-assisted deep eutectic solvent (DES) pretreatment coupled with high-pressure homogenization. A DES based on choline chloride and lactic acid was employed, and LCNFs prepared by conventional DES pretreatment at 110°C (LCNF-110) and 130°C (LCNF-130) were used for comparison. Although MW treatment offered a high removal of lignin (70%) and hemicellulose (90%) within a short time (110 s), the morphological observations by scanning and transmission electron microscopies revealed excellent defibrillation of the conventionally heat-treated samples. Likewise, LCNF-110 and LCNF-130 exhibited high tensile strengths of 154.6 ± 5.0 and 136.8 ± 1.2 MPa, respectively, whereas that of LCNF-MW was only 75.6 ± 1.4 MPa. Interestingly, LCNF-MW with a lignin content between that of LCNF-110 and LCNF-130 exhibited high thermal stability (Tmax 309.6°C) and potent antioxidant properties. However, the lignin contents of the LCNFs determined their UV-radiation blocking efficiency, where LCNF-110 > LCNF-MW > LCNF-130. Furthermore, all LCNF films exhibited good visible-light transparency, flexibility, and water contact angles (> 87°), indicating their promising potential for packaging applications.

Recently, gold nanoparticles (AuNPs) are extensively used as peroxidase mimics. However, low catalytic activity, high synthesis cost, substrate-induced aggregation in reaction medium and difficulty in recovery and reuse still remain as major challenges. Here, a novel, simple, spontaneous, and reagent-less in-situ method for the production of AuNPs using dialdehyde cellulose nanofibrils (DACNF) is proposed. AuNPs synthesis time and size were greatly influenced by aldehyde content and the optimal aldehyde content for ultra-small AuNPs (≈10 nm) was 2.1 mM/g. AuNPs@DACNFs exhibited broad-spectrum peroxidase activity and steady-state kinetics revealed their better kinetic parameters (low K

In the present study, we have successfully synthesized and characterized carboxy methyl cashew gum modified gold nanoparticles (CMCG-AuNPs) via a microwave-assisted method and used as a calorimetric probe for selective detection of Hg

In the current work, a silver nanoparticles/nitrogen-doped carbon dots (AgNPs/NCDs) nanocomposite was prepared by a microwave-assisted method that does not require additional reducing or stabilizing agents. Multiple analytical techniques were used to characterize the prepared nanocomposite. The nanocomposite exhibited a surface plasmon resonance (SPR) absorption peak at 420 nm, indicating the development of AgNPs with NCDs. Further, HRTEM results confirmed the formation of the nanocomposite with the appearance of lattice fringes of both materials. Additionally, the nanocomposite did not show any precipitation even after two months of storage. The nanocomposite exhibited high catalytic activity towards the reduction of rhodamine B (RhB, 98.83%), methyl red (MR, 97.14%) and 4-nitrophenol (4-NP, 99.95%) at ambient temperature. Besides, the kinetic analysis revealed that the reduction reaction followed pseudo-first-order kinetics and the calculated rate constants (k) for rhodamine B (RhB), methyl red (MR) and 4-nitrophenol (4-NP) were found to be 0.0296 s−1, 0.0233 s−1 and 0.029 s−1, respectively. Moreover, it is a reusable and stable catalyst for reduction reactions up to five cycles without significant loss in catalytic activity. Finally, a plausible mechanism for the reduction of pollutants is also discussed in detail. As a whole, the prepared nanocomposite might display stunning behaviour for wastewater treatment applications.

In this study, the effect of lignin esterification with fatty acid chloride on the properties of lignin and lignin/poly(lactic acid) (PLA) composites was investigated. Lignocellulose (Pinus densiflora S. et Z.) was treated using a deep eutectic solvent (DES) with choline chloride (ChCl)/lactic acid (LA). From the DES-soluble fraction, DES-lignin (DL) was isolated by a regeneration process. Lignin esterification was conducted with palmitoyl chloride (PC). As the PC loading increased for DL esterification, the Mw of esterified DL (EDL) was increased, and the glass transition temperature (Tg) was decreased. In DL or EDL/PLA composite films, it was observed that EDL/PLA had cleaner and smoother morphological characteristics than DL/PLA. The addition of DL or EDL in a PLA matrix resulted in a deterioration of tensile properties as compared with neat PLA. The EDL/PLA composite film had a higher tensile strength and elastic modulus than the DL/PLA composite film. DL esterification decreased water absorption with lower water diffusion coefficients. The effect of lignin esterification on improving the compatibility of lignin and PLA was demonstrated. These results are expected to contribute to the development of high-strength lignin composites.

Although photocatalytic degradation is an ideal strategy for cleaning environmental pollution, it remains challenging to construct a highly efficient photocatalytic system by steering the charge flow in a precise manner. In this work, a novel, highly efficient, stable, and visible light active hybrid photocatalytic system consisting of FeWO4 and g-C3N4 nanosheets (CNNs) has been successfully prepared by an in situ self-assembly solvothermal approach. Several characterization techniques were employed to study the phase structures, morphologies, optical properties, surface composition and chemical state of the as-prepared samples. SEM and TEM results demonstrated that the FeWO4 nanoparticles are uniformly dispersed on the surface of CNNs with a diameter of about 10–20 nm, which could provide maximum interfacial contact and a synergistic coupling effect between FeWO4 and CNNs. XPS and FTIR results confirmed that there was strong electrostatic interaction between FeWO4 and CNNs, suggesting the formation of heterojunctions between them. In addition, UV-DRS and PL spectroscopy revealed that the FeWO4/CNN composites exhibited increased visible light absorption and improved charge generation/separation efficiency. As a result, the photocatalytic activity of the FeWO4/CNNs was enhanced in comparison with pure FeWO4 and CNNs for rhodamine B (RhB) and tetracycline (TC) degradation under natural sunlight irradiation. The photocatalytic efficiency of the optimal FeWO4/CNN composite (10 wt% FeWO4/CNNs) for the degradation of RhB (TC) was about 13.26 (4.95) and 86.2 (31.1) times higher than that of pure FeWO4 and CNNs, respectively. Meanwhile, the 10 wt% FeWO4/CNN sample exhibits good photocatalytic stability in recycling experiments. The enhanced photocatalytic activity may be attributed to the formation of the Z-scheme system between FeWO4 and CNNs, effectively prolonging the lifetime of the photoexcited electrons generated by CNNs and the photoexcited holes generated by FeWO4, which was subsequently confirmed by the active species trapping experiments and the calculation of relative band alignments. This work opens up a new feasible avenue to synthesize visible light active Z-scheme photocatalysts for application in energy production and environmental remediation.

Nanozyme-based dye degradation methods are promising for the remediation of water pollution. Though Pd nanoparticles (PdNPs) are known to act as nanozymes, their dye degradation capability has not been investigated. Low nanozyme activities, easy aggregation, difficulties in recovery and reuse are the major challenges in achieving this. For the first time, cellulose nanofibrils-supported PdNPs (PdNPs/PCNF) as a novel nanozyme with good peroxidase and oxidase-mimicking activities and easy recyclability is explored for dye degradation. An efficient and rapid method of PdNPs/PCNF preparation was demonstrated by adjusting the pH and microwave irradiation. Enzyme kinetic studies revealed good kinetic parameters and specific activities of 415 and 277 U/g for peroxidase and oxidase, respectively. PdNPs/PCNF offered 99.64% degradation of methylene blue within 12 min (0.468 min

Effectual degradation of toxic water contaminants is a crucial step in water purification and designing an efficient semiconductor based hybrid structure photocatalyst is a good approach to achieve this. Benefiting from the combination of semiconductors, a series of novel visible-light active flower-like MoS

The present work is emphasized on converting toxic cigarette butts (CBs) into highly fluorescent N,S-codoped carbon dots by a facile hydrothermal approach and exploring their multiple applications. The as-produced carbon dots (CBCDs) exhibited bright and stable fluorescence with a quantum yield of 26% and used as a label-free probe for “on–off–on” sequential detection of Fe3+ and ascorbic acid (AA). The fluorescence of CBCDs can be significantly quenched by Fe3+ ions through static quenching and restored upon the subsequent addition of AA due to the reduction of Fe3+ to Fe2+ by AA. This nanoprobe presented great selectivity and excellent sensitivity to Fe3+ and AA with a detection limit of 0.13 and 0.2 μM, respectively. Furthermore, the nanoprobe was extended to biosystem (intracellular detection) and successfully applied for the detection of Fe3+ in real water (tap, bore, and pond) and AA in biological samples (human urine and serum). In addition, we have constructed an IMPLICATION logic gate based on these unique sensing characteristics. The “visible–invisible” and “UV–visible” property explored their use as invisible ink for security applications. Furthermore, highly photostable fluorescent polymer films were prepared by incorporating CBCDs in poly(vinyl alcohol). It is anticipated that the strong and stable fluorescence emission nature of these films might find direct or indirect applications in various optical/optoelectronic devices, ranging from fluorescent displays to light-emitting diodes.

Here we demonstrate a rapid green synthetic approach for the production of gold nanoparticles (AuNPs) using microwave irradiation, in which Annona squamosa L (AS) fruit waste extract served as a sole agent for both reduction and stabilization. Synthetic conditions were optimized by monitoring the changes surface plasmon resonance (SPR) peak, zeta potential and DLS size distribution. TEM results revealed that under optimized synthetic conditions monodispersed and spherical nanoparticles with average diameter of 5 ± 2 nm could be achieved. The possible mechanism involved in the formation of AuNPs was interpreted by FTIR. The formed AuNPs dispersion remained stable to environmental conditions like temperature, ionic strength and pH of the medium and exhibited high shelf life. Further they exhibited admirable catalytic activity for the efficient reduction of Congo red & Methylene Blue and 4-Nitrophenol in the presence of NaBH4, which is stable even after five cycles of reaction.

Herein, we developed a gold nanoparticles (AuNPs) based label free colorimetric probe for the sensitive and selective detection of Copper (II) ions (Cu2+). Fabrication of the detection system involves a single step in which plant derived, nontoxic polysaccharide carboxymethyl gum karaya (CMGK) acts as reducing, stabilizing and functionalizing agent. Synthetic conditions were optimized by using UV–Vis spectra, zeta potential and DLS analysis and as synthesized AuNPs were thoroughly characterized by TEM, FTIR, and XRD analysis. They exhibited excellent stability to conditions like pH, salt and have a longer shelf life. These CMGK capped AuNPs exhibited a selective colorimetric response to Cu2+ ions with a visible colour change from red to blue, which could be due to the Cu2+ induced aggregation and the same was confirmed by TEM and DLS analysis. The detection conditions such as pH, amount of nanoparticles used and incubation time were optimized. Under the optimal detection conditions, the present system exhibited a good linear correlation (R2 = 0.998) in the range of 10–1000 nM of copper with a limit of detection 10 nM. Further the method was successfully applied for the detection of copper in real water samples and biological samples (human plasma and urine).

In this work, novel ternary composites were prepared by depositing both carbon dots (CDs) and Ag nanoparticles (AgNPs) onto the surface of g-C 3 N 4 nanosheets (CNNs). The as-prepared samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) techniques. The characterization results demonstrated that the CDs and AgNPs were well distributed on the surface of CNNs. The photocatalytic activities of all the samples were evaluated by degrading methyl orange (MO) and p-nitrophenol (PNP) in aqueous media under sunlight irradiation. Among the prepared samples, CNNs decorated with 2 wt% CDs and 1 wt% AgNPs showed higher degradation performance. The enhanced performance was attributed to the improved light harvesting capability and effective charge carrier separation at the AgNPs/CDs/CNNs interface. Superoxide radical species and photogenerated holes were found to be predominant reactive species responsible for the photodegradation of these pollutants. A suitable mechanism was proposed and discussed in detail.

Here, we report a novel, facile and green approach for the synthesis of highly fluorescent carbon dots (CDs) with 28% quantum yield by utilizing onion waste as a precursor and by employing a simple autoclave. Optical and physicochemical properties of as synthesized CDs were studied using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS), X-ray diffraction (XRD), Raman, thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), UV-visible, fluorescence spectroscopy and elemental analysis. These CDs exhibited high aqueous dispersibility, excitation dependent fluorescence emission and excellent stability to various effects like pH, high ionic strength and continuous irradiation. It was observed that the presence of Fe3+ ions could result in a strong fluorescence quenching, hence these CDs were applied as a fluorescent probe for the selective & sensitive detection of Fe3+ ions and a good linear correlation (R2 = 0.996) in the range of 0–20 μM with a detection limit of 0.31 μM was obtained. Cytotoxicity studies performed on both normal (HEK-293 cells) and cancerous (HeLa) cells revealed their excellent biocompatibility and they were further employed as fluorescent probes for multicoloured (blue, green and red) imaging of HeLa cells. Impressed by their high selectivity, photo stability and excellent biocompatibility, the Fe3+ detection capability of these CDs was further evaluated in HeLa cells and applied for real water samples.

Sunlight-driven C–TiO2/FeTiO3 composites were synthesized with different weight fractions of FeTiO3. The as-prepared samples were characterized by UV–Visible diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and photoluminescence. Under sunlight irradiation, the C–TiO2/FeTiO3 photocatalysts degraded methyl orange (MO) efficiently and displayed much higher photocatalytic activity than that of pure FeTiO3 or carbon-doped titanium dioxide (C–TiO2), and the C–TiO2/FeTiO3 photocatalyst with 10 wt% of FeTiO3 exhibited the highest photocatalytic activity. The enhancement of photocatalytic activity was mainly ascribed to the formation of a heterojunction between C–TiO2 and FeTiO3, which facilitated the transfer and separation of photogenerated electron–hole pairs. The quenching effects of different scavengers demonstrated that the reactive superoxide radicals (·O2 −) and hydroxyl radicals (·OH) played a major role in the MO degradation. The possible photocatalytic mechanism is discussed on the basis of the band structures of C–TiO2 and FeTiO3. To further enhance the photocatalytic efficiency, double-heterojunctioned CQD/C–TiO2/FeTiO3 composite was prepared by loading carbon quantum dots onto the C–TiO2/FeTiO3 surface.

A one step thermal carbonization method for the preparation of solid state emitting N-doped carbon dots (NCDs) powder with hydrophobic nature is reported here. This method directly offers glowing NCDs powder in large quantities and do not involve tedious purification and drying steps. Physicochemical properties of as produced NCDs were explored using various analytical techniques and optical properties were studied in different solvents. The NCDs powder was applied for the rapid visualization of latent fingerprints (LFPs) on various porous and non-porous surfaces. With their green emission, NCDs were able to provide sufficient contrast on auto-fluorescent surfaces also. The LFPs developed with NCDs powder clearly presented level 2 and level 3 ridge details which are sufficient for the individual identification.

Although photocatalytic degradation is an ideal strategy for cleaning environmental pollution, it remains challenging to construct a highly efficient photocatalytic system by steering the charge flow in a precise manner. In this work, a novel, highly efficient, stable, and visible light active hybrid photocatalytic system consisting of FeWO

Stable gold nanoparticles (AuNPs) were synthesized using salmalia malabarica gum as both reducing and capping agent. It is a simple and eco-friendly green synthesis. The successful formation of AuNPs was confirmed by UV–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction and transmission electron microscopy (TEM). The synthesized AuNPs were characterized by a peak at 520–535 nm in the UV–Vis spectrum. The X-ray diffraction studies indicated that the resulting AuNPs were highly crystalline with face-centred cubic geometry. TEM studies showed that the average particle size of the synthesized AuNPs was 12 ± 2 nm. FTIR analysis revealed that –OH groups present in the gum matrix might be responsible for the reduction of Au+3 into AuNPs. The synthesized AuNPs exhibited good catalytic properties in the reduction of methylene blue and Congo red.

Here, we developed a simple green approach for the synthesis of highly fluorescent nitrogen doped carbon dots (NCDs) using Lantana camara berries. Optical and physicochemical properties of as synthesized NCDs were extensively studied by using various analytical techniques. NCDs exhibited bright fluorescence with Quantum yield as high as 33.15%, which is stable to various effects like heat, pH, ionic strength and continuous irradiation. Furthermore, the NCDs presented highly selective and sensitive fluorescence response towards Pb2+ which explored their potential to serve as a label-free fluorescent probe for the effective detection of Pb2+. As developed NCDs based probe exhibited a great linear response (R2=0.998) towards Pb2+ in the concentration range of 0-200nM with a detection limit of 9.64nM. The probe further presented high precision without any interference and was successfully applied for the detection of Pb2+ in the real water and human sera (serum and urine) samples. Cytotoxicity studies on both cancerous (human breast adenocarcinoma MCF-7) and normal (Human embryonic kidney HEK-293) cell lines revealed their excellent biocompatibility. With their low cytotoxicity, strong fluorescence and excitation-dependent emission, NCDs were successfully applied as multi-colour bioimaging agents and Pb2+ detection capabilities were further evaluated in live cells.

Background Herein, we report a green, microwave irradiated synthesis of gold nanoparticles by using a simple, low cost and ecofriendly technique. The green technique has been developed for the synthesis of gold nanoparticles (AuNPs) from HAuCl4 using papaya leaf extract. The papaya leaf extract served both as a reductant and a stabilizer. Method The synthesized AuNPs had been characterized by UV-Visible spectrophotometer, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Zeta potential and Transmission electron microscopy (TEM) techniques. Results The results indicated that the synthesized nanoparticles were crystalline, stable, well dispersed and spherical in shape and had an average diameter of 15 ± 2 nm. The AuNPs showed excellent catalytic activity for the reduction of p-nitrophenol (4-NP) to p-aminophenol (4-AP) in the presence of NaBH4. The effects of concentration of NaBH4, catalyst dose and temperature on the formation of nanoparticles were studied. The activation energy was found to be 28.15 ± 1.14 kJ/mol. Conclusions The papaya leaf extract capped AuNPs are highly stable, and have showed effective catalytic activity in the reduction of 4-NP to 4-AP and antimicrobial activity on both gram-positive and gram-negative bacteria.

Photocatalytic materials for environmental remediation of organic pollutants and heavy metals require not only a strong visible light response and high photocatalytic performance, but also the regeneration and reuse of catalysts. In this work, 1D/2D V2O5 nanorods/g-C3N4 nanosheets (VONRs/CNNs) composites were prepared by a facile impregnation method and employed in the degradation of a Congo red (CR) and reduction of Cr (VI) under sunlight irradiation. The as-prepared samples were studied by several characterization techniques including XRD, SEM, TEM, EDS, XPS, FTIR, UV–vis DRS and PL. Results revealed that the interface interaction between VONRs and CNNs was recognized via V2O5 nanorods loading on the surface of g-C3N4 nanosheets, improving the separation and transfer of photogenerated electron-hole pairs and restraining the recombination rate of charge carriers. As a result, the photocatalytic activity of the composites was enhanced in comparison with pure CNNs and VONRs. The photocatalytic efficiency of optimal composite (4-VONRs/CNNs) for the removal of CR (Cr (VI)) was about 9.33 (4.22) and 73.52 (19.2) times higher than that of pure CNNs and VONRs, respectively. Meanwhile, the 4-VONRs/CNNs exhibited good photocatalytic stability in recycling experiments. Such enormous enhancement in photocatalytic performance was predominantly ascribed to the efficient separation and transfer of photogenerated electron-hole pairs at the VONRs/CNNs interface imparted through the direct Z-scheme charge carrier migration mechanism. Moreover, the energy band structure and the quenching effects of different scavengers demonstrated that the electrons of CNNs and holes of VONRs with higher oxidizability and reducibility are the real participants in photocatalytic reactions.

Aim The present study is to prepare and assess Irbesartan loaded surface solid dispersions (SSD) for enhancing the solubility and bioavailability of poor soluble drug. Method Irbesartan loaded SSD were prepared by co-evaporation method by using five different super disintegrants like crospovidone, croscarmellose sodium, potato starch, sodium starch glycolate and microcrystalline cellulose in three different drug–carrier ratios and evaluate for the in vitro drug release. Results The prepared formulations were white in colour and free flowing. The spectral data reveals that there are no drug-polymer interactions. The P-XRD studies showed decrease in crystallinity of drug formulations when compared to the pure state of the drug. The SEM study was found to be irregular matrices due to the porous nature of the carrier with the fine particles of the drug embedded in it. The in vitro dissolution studies of surface solid dispersion of crospovidone with drug to carrier ratio of 1:10 showed highest dissolution rate with the dissolution efficiency of 98.18% (10 min) in comparison to the other formulations due to deposition of drug on the surface of an inert carrier leading to a reduction in the particle size of the drug, thereby providing a faster dissolution rate. Conclusion The surface solid dispersion technique has been shown as a popular approach to improve the dissolution rate of poor soluble Irbesartan.

A facile and eco-friendly method for green synthesis of silver nanoparticles (AgNPs) has been developed using gum tragacanth (GT) (Astragalus gummifer), an abundantly available natural phyto-exudate in India, employing a novel method of ultrasonication process. Silver nanoparticles were prepared by the reduction of silver nitrate solution by the aqueous extract of gum tragacanth by ultrasonication method at 45 °C for about 45 min. The aqueous extract of the gum acts as a reducing as well as stabilizing agent. The resultant AgNPs were characterized by ultraviolet-visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD) techniques. The influence of gum concentration and silver precursor concentration on the synthesis of AgNPs was studied. The role and effectiveness of nanoparticles in the catalytic reduction of a cationic dye methylene blue (MB), and an anionic azo dye Congo red (CR), were also studied. FTIR analysis revealed that –OH groups present in the gum matrix might be responsible for the reduction of Ag+ into AgNPs. The X-ray diffraction studies indicated that the resulting AgNPs were highly crystalline with face-centered cubic geometry. TEM studies showed that the average particle size of the synthesized AgNPs was 18 ± 2 nm. The study highlights the green synthesis of GT-capped AgNPs and the rapid reduction of carcinogenic and toxic contaminants such as MB and CR with the help of GT-capped AgNPs in an eco-friendly manner.