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Towards fabricating a hybrid biodegradable multifunctional nanocomposite, cellulose nanocrystal (CNC), reduced graphene oxide (rGO) and silver (Ag) nanoparticles were reinforced into polyvinyl alcohol (PVA) polymer matrix. One-step reduction process was followed, composed of reducing graphene oxide (GO) and silver nitrate (AgNO 3 ) into rGO and Ag nanoparticles through hydrazine hydrate (chemical reduction method), respectively. Uniformly dispersed CNC, rGO and Ag nanoparticles in PVA matrix led to an increment in modulus by 184% of PVA demonstrating the reinforcement outcome of CNC, rGO and Ag. PVA/CNC/rGO/Ag nanocomposite showed the Ag + ions sustained release from PVA studied using Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The incorporation and elemental composition of CNC, rGO and Ag nanoparticles into nanocomposite were interpreted through FTIR (Fourier Transform Infrared Spectroscopy) and XPS (X-ray photoelectron spectroscopy) technique, respectively. All prepared nanocomposites with different wt% of Ag (PVA, PVA/CNC, PVA/CNC/rGO/Ag) were non-toxic to HEK-293 cell line and exhibited improved antibacterial property against E. coli and S. aureus due to a combination of Ag + ions (release from Ag nanoparticles) and rGO (having antibacterial effect). Thus, the combined effect of CNC, rGO and Ag in PVA matrix distinctively resulted into a multifunctional hybrid nanocomposite for potential use in tissue engineering and packaging applications., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In this work, both cellulose nanocrystals (CNC) and reduced graphene oxide (rGO) were reinforced into poly-lactic acid (PLA) to enhance the stiffness, strength and thermal stability of the pure polymer i.e. PLA. To enhance the uniform dispersion of CNC (which is a major concern with PLA) and rGO in the hydrophobic polymer matrix, CNC's surface was first modified using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation method followed by surface grafting of TEMPO-oxidized CNC (TOCNC) performed with polyethylene glycol (PEG). The PEG-grafting on crystalline region of cellulose nanofibrils was achieved through ionic bonds by applying ion-exchange method (simple and easy method). The obtained PEG-grafted-TOCNC indicated uniform dispersion at the nanoelement level in non-polar (organic) compound i.e. chloroform. Further, the PEG-grafted-TOCNC/chloroform with different blend ratios, PLA/chloroform and rGO/chloroform solution were mixed together and solvent casted onto a petri-dish to obtain PLA/PEG-TOCNC/rGO nanocomposite film. The tensile strength and thermal stability were remarkably improved for the film containing highest wt% of modified CNC. In addition to this, the film showed reduced water vapor barrier properties and antioxidant activity which enables it to be used as a packaging films. Moreover, the film displayed negligible toxicity and cytocompatibility to fibroblast cells C3H10T1/2. These attractive properties of PLA/PEG-TOCNC/rGO nanocomposite film render the application of film as a scaffold in tissue engineering field and in packaging application., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In the present study, cellulose nanocrystals (CNCs) and reduced graphene oxide (rGO) were successfully synthesized via acid hydrolysis and modified Hummer's method, respectively. Further, the synthesized CNCs and rGO were incorporated into poly-lactic acid (PLA) matrix using solution casting method utilizing different weight (wt.) % of CNCs (nanofiller) and rGO. The successful synthesis of various nanoformulations were confirmed by several characterization techniques including Transmission Electron Microscopy (TEM), Field-Emission Scanning Electron Microscopy (FE-SEM) and Fourier Transform Infrared Spectroscopy (FTIR) analysis. Hydrophilicity measurement of the film was done by wettability analysis. The mechanical property evaluation of scaffold showed considerable increased tensile strength of PLA/CNC/rGO nanocomposite upto 23%, with increase in elongation at break (ε b ) indicating the ductile behavior of nanocomposite as compare to pristine PLA. The distinct anti-bacterial efficacy of PLA/CNC/rGO nanocomposite film was found against both Gram positive Staphylococcus aureus (S.aureus) and Gram negative Escherichia coli. (E. coli) bacterial strains respectively. Furthermore the in-vitro cell based cytotoxicity assay showed negligible cytotoxicity of fibroblast cell line (NIH-3T3) upon treatment with nanocomposite film. Therefore, the as fabricated nanocomposite film possesses considerable potential in biomedical as well as in food packaging applications., (Copyright © 2016 Elsevier B.V. All rights reserved.)