Graphene layers have been transferred directly on to paper without any intermediate layers to yield G-paper. Resistive gas sensors have been fabricated using strips of G-paper. These sensors achieved a remarkable lower limit of detection of ∼300 parts per trillion (ppt) for NO2, which is comparable to or better than those from other paper-based sensors. Ultraviolet exposure was found to dramatically reduce the recovery time and improve response times. G-paper sensors are also found to be robust against minor strain, which was also found to increase sensitivity. G-paper is expected to enable a simple and inexpensive low-cost flexible graphene platform.
Repair
of critical size bone defects is a clinical challenge that
usually necessitates the use of bone substitutes. For successful bone
repair, the substitute should possess osteoconductive, osteoinductive,
and vascularization potential, with the ability to control post-implantation
infection serving as an additional advantage. With an aim to develop
one such substitute, we optimized a zinc-doped hydroxyapatite (HapZ) nanocomposite decorated on reduced graphene oxide (rGO),
termed as G3HapZ, and demonstrated its potential
to augment the bone repair. The biocompatible composite displayed
its osteoconductive potential in biomineralization studies, and its
osteoinductive property was confirmed by its ability to induce mesenchymal
stem cell (MSC) differentiation to osteogenic lineage assessed by
in vitro mineralization (Alizarin red staining) and expression of
osteogenic markers including runt-related transcription factor 2 (RUNX-2),
alkaline phosphatase (ALP), type 1 collagen (COL1), bone morphogenic
protein-2 (BMP-2), osteocalcin (OCN), and osteopontin (OPN). While
the potential of G3HapZ to support vascularization
was displayed by its ability to induce endothelial cell migration,
attachment, and proliferation, its antimicrobial activity was confirmed
using S. aureus. Biocompatibility of
G3HapZ was demonstrated by its ability to induce bone regeneration
and neovascularization in vivo. These results suggest
that G3HapZ nanocomposites can be exploited
for a range of strategies in developing orthopedic bone grafts to
accelerate bone regeneration.
The
in vivo use of carbon dots (CDs) in biomedical applications
might result in its interaction with the endothelial cells (ECs) lining
the blood vessels. It is important to assess its response to CDs because
the cells play a key role in the regulation of blood vessel function.
Using a widely studied CD synthesized from a combination of citric
acid and urea (CD-urea), we herein report the response of ECs to its
exposure. The biocompatible CD-urea exhibited a proangiogenic response
in human vein ECs. The cascade of events in the ECs following CD-urea
uptake, including its influence on reactive oxygen species (ROS),
nuclear factor κ-light-chain enhancer of activated B cells (NF-κB),
and gene expression, was investigated comprehensively using confocal
and quantitative polymerase chain reaction studies. While new blood
vessel formation is favored in wound healing, it is not recommended
in tumor growth and metastasis. Our study demonstrates the need for
evaluating the response of ECs to CDs before exploiting its potential
in vivo application.
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