In this study, an injectable thermoresponsive
hydroxypropyl guar-graft-poly(N-vinylcaprolactam)
(HPG-g-PNVCL) copolymer was synthesized by graft
polymerization.
The reaction parameters such as temperature, time, monomer, and initiator
concentrations were varied. In addition, the HPG-g-PNVCL copolymer was modified with nano-hydroxyapatite (n-HA) by
in situ covalent cross-linking using divinyl sulfone (DVS) cross-linker
to obtain HPG-g-PNVCL/n-HA/DVS composite material.
Grafted copolymer and composite materials were characterized using
Fourier transform infrared spectroscopy, thermogravimetric analysis,
proton nuclear magnetic resonance spectroscopy (1H NMR),
and differential scanning calorimetry. The morphology of the grafted
copolymer (HPG-g-PNVCL) and the composite (HPG-g-PNVCL/n-HA/DVS) was examined using scanning electron microscopy
(SEM), which showed interconnected porous honeycomb-like structures.
Using Ultraviolet−visible spectroscopy, low critical solution
temperature for HPG-g-PNVCL was observed at 34 °C,
which is close to the rheology gel point at 33.5 °C. The thermoreversibility
of HPG-g-PNVCL was proved by rheological analysis.
The HPG-g-PNVCL hydrogel was employed for slow release
of the drug molecule. Ciprofloxacin, a commonly known antibiotic,
was used for sustainable release from the HPG-g-PNVCL
hydrogel as a function of time at 37 °C because of viscous nature
and thermogelation of the copolymer. In vitro cytotoxicity study reveals
that the HPG-g-PNVCL thermogelling polymer works
as a biocompatible scaffold for osteoblastic cell growth. Additionally,
in vitro biomineralization study of HPG-g-PNVCL/n-HA/DVS
was conducted using a simulated body fluid, and apatite-like structure
formation was observed by SEM.
Nitrophenols
(NPs) and related derivatives are industrially important
chemicals, used notably to synthesize pharmaceuticals, insecticides,
herbicides, and pesticides. However, NPs and their metabolites are
highly toxic and mutagenic. They pose a serious threat to human health
and ecosystem. Current work was undertaken to develop a suitable visible-light
active catalyst for the sustainable and efficient mineralization of
NPs in an aqueous environment. Nanocrystalline cellulose (NCs)-based
nitrogen-doped titanium dioxide and carbonaceous material (N-TiO
2
/C) was synthesized by pyrolysis and sol–gel methods
using NCs, polydopamine, and TiO
2
. The synthesized N-TiO
2
/C was characterized using different analytical techniques.
Photocatalytic degradation of NPs under visible light indicated that
acidic pH (3) was most suitable for the optimal degradation. 4-NP
degradation followed both pseudo-first-order (
R
2
= 0.9985) and Langmuir–Hinshelwood adsorption kinetic
models (adsorption constant,
K
LH
= 1.13
L mg
–1
). Gas chromatography–mass spectrometry
and ion chromatography analysis confirmed the total mineralization
of 4-NP into smaller molecular fragments such as acids, alcohols,
and nitrates. The total organic carbon showed that 67% of total carbon
present in 4-NP was mineralized into CO
2
and CO. The catalyst
was recycled for five consecutive cycles without losing its catalytic
activities. The degradation mechanism of NPs with N-TiO
2
/C was also explored.
Biocompatible bone implants composed of natural materials are highly desirable in orthopedic reconstruction procedures. In this study, novel and ecofriendly bionanocomposite hydrogels were synthesized using a blend of hydroxypropyl guar (HPG), poly vinyl alcohol (PVA), and nano-hydroxyapatite (n-HA) under freeze-thaw and mild reaction conditions. The hydrogel materials were characterized using various techniques. TGA studies indicate that both composites, HPG/PVA and HPG/PVA/n-HA, have higher thermal stability compared to HPG alone whereas HPG/PVA/n-HA shows higher stability compared to PVA alone. The HPG/PVA hydrogel shows porous morphology as revealed by the SEM, which is suitable for bone tissue regeneration. Additionally, the hydrogels were found to be transparent and flexible in nature. In vitro biomineralization study performed in simulated body fluid shows HPG/PVA/n-HA has an apatite like structure. The hydrogel materials were employed as extracellular matrices for biocompatibility studies. In vitro cell viability studies using mouse osteoblast MC3T3 cells were performed by MTT, Trypan blue exclusion, and ethidium bromide/acridine orange staining methods. The cell viability studies reveal that composite materials support cell growth and do not show any signs of cytotoxicity compared to pristine PVA. Osteoblastic activity was confirmed by an increased alkaline phosphatase enzyme activity in MC3T3 bone cells grown on composite hydrogel matrices.
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