The vast domain of regenerative medicine comprises complex interactions between specific cells’ extracellular matrix (ECM) towards intracellular matrix formation, its secretion, and modulation of tissue as a whole. In this domain, engineering scaffold utilizing biomaterials along with cells towards formation of living tissues is of immense importance especially for bridging the existing gap of late; nanostructures are offering promising capability of mechano-biological response needed for tissue regeneration. Materials are selected for scaffold fabrication by considering both the mechanical integrity and bioactivity cues they offer. Herein, polycaprolactone (PCL) (biodegradable polyester) and ‘nature’s wonder’ biopolymer silk fibroin (SF) are explored in judicious combinations of emulsion electrospinning rather than conventional electrospinning of polymer blends. The water in oil (W/O) emulsions’ stability is found to be dependent upon the concentration of SF (aqueous phase) dispersed in the PCL solution (organic continuous phase). The spinnability of the emulsions is more dependent upon the viscosity of the solution, dominated by the molecular weight of PCL and its concentration than the conductivity. The nanofibers exhibited distinct core-shell structure with better cytocompatibility and cellular growth with the incorporation of the silk fibroin biopolymer.
Super-paramagnetic
iron oxide nanoparticles (SPIONs) have multiple
theranostics applications such as T2 contrast agent in magnetic resonance
imaging (MRI) and electromagnetic manipulations in biomedical devices,
sensors, and regenerative medicines. However, SPIONs suffer from the
limitation of free radical generation, and this has a certain limitation
in its applicability in tissue imaging and regeneration applications.
In the current study, we developed a simple hydrothermal method to
prepare carbon quantum dots (CD) doped SPIONs (FeCD) from easily available
precursors. The nanoparticles are observed to be cytocompatible, hemocompatible,
and capable of scavenging free radicals in vitro.
They also have been observed to be useful for bimodal imaging (fluorescence
and MRI). Further, 3D printed gelatin–FeCD nanocomposite nanoparticles
were prepared and used for tissue engineering using static magnetic
actuation. Wharton’s jelly derived mesenchymal stem cells (MSCs)
were cultured on them with magnetic actuation and implanted at the
subcutaneous region. The tissues obtained have shown features of both
osteogenic and chondrogenic differentiation of the stem cells in vivo. In vitro, PCR studies show MSCs
express gene expression of both bone and cartilage-specific markers,
suggesting FeCDs under magnetic actuation can lead MSCs to go through
differentiating into an endochondral ossification route.
Small organic luminogens, owing to their contrasting stimuli-responsive fluorescence in solution along with strong emission in aggregated and solidstates, have been employed in optoelectronic devices, sensors, and bioimaging. Pyrene derivatives usually exhibit strong fluorescence and concentration-dependent excimer/aggregate emission in solution. However, the impacts of microenvironments on the monomer and aggregate emission bands and their relative intensities in solution, solid, and supramolecular aggregates are intriguing. The present study delineates a trade-off between the monomer and aggregate emissions of a pyrene-benzophenone derivative (ABzPy) in solution, in the solid-state, and in nanoaggregates through a combined spectroscopic and microscopic approach. The impact of external stimuli (viscosity, pH) on the aggregate emission was demonstrated using steady-state and time-resolved spectroscopy, including fluorescence correlation spectroscopy and fluorescence anisotropy decay analysis. The aggregate formation was noticed at a higher concentration (>10 μM) in solution, at 77 K (5 μM), and in the solid-state due to the π−π stacking interactions (3.6 Å) between two ABzPy molecules. In contrast, no aggregate formation was observed in the viscous medium as well as in a micellar environment even at a higher concentration of ABzPy (50 μM). The crystal structure analysis further shed light on the intermolecular hydrogen-bonding-assisted solid-state emission, which was found to be highly sensitive toward external stimuli like pH and mechanical forces. The broad emission band comprising both monomer and aggregate in the aqueous dispersion of nanoaggregates was used for the specific cellular imaging of lysosomes and lipid droplets, respectively.
Mandible subcondylar fractures have very high complication rate, yet there is no consensus in a suitable plate design for optimal patient outcomes. The present study is aimed at understanding the subcondylar fracture fixation by comparing load transfer in intact and reconstructed fractured mandibles with five different plates: single mini, trapezoid, lambda, strut, and double-mini plates under the complete mastication cycle. Under contralateral molar occlusion (LMOL), the single mini plate resulted in the highest strains. On the contrary, during ipsilateral molar clenching (RMOL), the tensile and compressive strain distributions were found to be reversed, with the tensile strains at the posterior border resulting in lesser strain in reconstructed mandible with single mini plate. Owing to the reduced strains in the reconstructed mandibles, the contralateral molar clenching task is preferred during the immediate post-surgery period for patients. Under this contralateral molar clenching, the peak von Mises stresses in the plate decreased with increase in the number of screws. Furthermore, the presence of two arms seems beneficial to neutralise the tensile and compressive strains across load cases. Consequently, double mini and trapezoid plates were found to perform better as compared to single mini plate during the entire mastication cycle for subcondylar fracture fixation.
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