Satyabrat Gogoi

Nano-Bio Engineered Carbon Dot-Peptide Functionalized Water Dispersible Hyperbranched Polyurethane for Bone Tissue Regeneration

The present study delves into a combined bio-nano-macromolecular approach for bone tissue engineering. This approach relies on the properties of an ideal scaffold material imbued with all the chemical premises required for fostering cellular growth and differentiation. A tannic acid based water dispersible hyperbranched polyurethane is fabricated with bio-nanohybrids of carbon dot and four different peptides (viz. SVVYGLR, PRGDSGYRGDS, IPP, and CGGKVGKACCVPTKLSPISVLYK) to impart target specific in vivo bone healing ability. This polymeric bio-nanocomposite is blended with 10 wt% of gelatin and examined as a non-invasive delivery vehicle. In vitro assessment of the developed polymeric system reveals good osteoblast adhesion, proliferation, and differentiation. Aided by this panel of peptides, the polymeric bio-nanocomposite exhibits in vivo ectopic bone formation ability. The study on in vivo mineralization and vascularization reveals the occurrence of calcification and blood vessel formation. Thus, the study demonstrates carbon dot/peptide functionalized hyperbranched polyurethane gel for bone tissue engineering application.

A renewable resource based carbon dot decorated hydroxyapatite nanohybrid and its fabrication with waterborne hyperbranched polyurethane for bone tissue engineering

Use of renewable resources in material science creates new opportunities for fabricating novel biomaterials. In this context, a carbon dot (CD) decorated hydroxyapatite (HAp) nanohybrid (CD@HAp) was synthesized by a simple one pot hydrothermal process. Different bio-based and waste materials were used in the synthesis of the nanohybrid. The aqueous extract of corms of Colocasia esculenta was used as the CD precursor, whereas egg shell was used to obtain CaO, which served as the precursor for HAp. The synthesized nanohybrid was characterized by using different analytical and spectroscopic techniques viz. FTIR, XRD, TEM, SEM/EDX and Raman spectroscopy. TEM and HRTEM images confirmed the formation of needle shaped HAp (length 60–80 nm, average diameter 20–30 nm) with decorated CDs over its surface. Elemental analysis showed a Ca/P ratio of 1.69, which is close to the Ca/P ratio (1.67) found in natural bone. Biological assessment of the nanohybrid demonstrated excellent cytocompatibility, cell proliferation and alkaline phosphatase activity against MG 63 osteoblast cell line. Synthesized CD@HAp was fabricated in situ with a tannic acid based waterborne hyperbranched polyurethane. Substantial improvement in the mechanical properties of the nanocomposite was perceived. These nanocomposite films were tested for osteogenic activities and the results confirmed its utility as a bone regenerating material. The overall results thus endorse development of a sustainable nanocomposite with high load bearing ability and profound bioactivity which can be employed for bone tissue engineering application.

Biobased waterborne hyperbranched polyurethane/NiFe2O4@rGO nanocomposite with multi-stimuli responsive shape memory attributes

A biobased waterborne hyperbranched polyurethane nanocomposite was fabricated with nickel ferrite/reduced graphene oxide nanohybrid (NiFe2O4@rGO) by following an in situ polymerization technique. NiFe2O4@rGO was prepared through a hydrothermal method. The prepared nanohybrid and nanocomposite were characterized by using different spectroscopic and analytical techniques. Various properties of the nanocomposite were also evaluated. The nanocomposite demonstrated excellent thermal stability (initial degradation temperature up to 335 °C) and good mechanical properties (tensile strength 24.23 MPa, elongation at break 280% and toughness 28.35 MJ m−3). The nanocomposite also exhibited outstanding multi-stimuli responsive shape memory behavior under sunlight, thermal and microwave (300 W) irradiation. Both the polymer matrix and nano-filler acted complementarily towards an efficient shape recovery behavior. The performance of the nanocomposite was found to be dependent on the nanomaterial loading. Thus, the present study showed that the developed nanocomposite can be used as a high performing, non-contact triggered smart material for advanced shape memory application.

A promising catalyst for exclusive para hydroxylation of substituted aromatic hydrocarbons under UV light

Herein, we describe a waterborne polymer/carbon dot nanocomposite system as an efficient, resourceful and sustainable photocatalyst for para-selective hydroxylation of substituted aromatic compounds using H2O2 under UV light. The polymer matrix and carbon dot generate a synergistic catalytic system. A unique structural attribute of the functionalities in this catalytic system attracts the aromatic substrates into close proximity and activates them. Additionally, the flexible molecular box-like structure of the hyperbranched polymer provides the ability for favorable three-point interaction with several substrates having various sizes by means of their multiple force networks and the increased accessibility of the active sites. The catalyst can be stored on the bench top for months and is reusable without considerable loss in its activity. The reaction was exclusively selective toward para hydroxylation irrespective of the nature of the substituents (electron donating or electron withdrawing) in the aromatic hydrocarbons. Hence, it is one of the most promising catalysts for selective hydroxylation of substituted aromatic hydrocarbons.

Electrochemical detection of monosodium glutamate in foodstuffs based on Au@MoS2/chitosan modified glassy carbon electrode

We report an amperometric immunosensor for the detection of monosodium glutamate (MSG) using a glassy carbon electrode modified with gold nanoparticle decorated on a molybdenum disulfide/chitosan (Au@MoS2/Ch) nanocomposite. In the present detection technique, Au@MoS2/Ch was used as a conductive matrix and anti-glutamate antibody was immobilized on to its surface via carbodiimide coupling method. Chemical and morphological attributes of the various components of the immunosensor were confirmed by UV-vis spectroscopy, SEM, TEM and XRD analysis. Electrochemical characterizations were carried out by CV, DPV and EIS. Overall results showed the effective fabrication of highly conductive Au@MoS2/Ch nanocomposite for sensitive electrochemical detection of MSG. A linear relationship was perceived between the change in current and concentration of MSG. The relationship was found to be consistent in the detection range of 0.05-200 µM. Statistical validation of the assay showed limit of detection and limit of quantification values as 0.03 and 0.1 µM, respectively (R2 = 0.99).