Nowadays controlling cellular responses and function of biological molecules is becoming one of the prime areas of focus in biomedical field. In this investigation, an attempt is made to generate in situ charge in bioactive glass (BAG) by incorporating BiFeO3 (BF, a multiferroic material). It is hypothesized that BF in BAG can accelerate cellular activities for rapid tissue healing with externally applied magnetic field due to in situ polarization. BAG composites with different amounts of BF (2 to 15 wt%) are prepared using ball milling followed by pressing and sintering. The composites are characterized in terms of microstructures, constituent phases, magnetic, and electrical properties. Further, in vitro cytotoxicity studies are performed to evaluate the influence of in situ polarization by culturing mouse preosteoblast cells (MC3T3) on BAG‐BF composites under different external magnetic field treatments. These in vitro cell‐materials interaction studies demonstrate that magnetic field strengths of 200 or 350 mT exposed for 30 min/day can enhance cell viability and proliferation on these composites up to three times. Hence, the authors expect that this investigation will enable further developments to extend the application of multiferroics in bone tissue engineering.
Developing
materials with remote controllability of macroscale
ligand presentation can mimic extracellular matrix (ECM) remodeling
to regulate cellular adhesion in vivo. Herein, we
designed charged mobile nanoligands with superparamagnetic nanomaterials
amine-functionalized and conjugated with polyethylene glycol linker
and negatively charged RGD ligand. We coupled negatively a charged
nanoligand to a positively charged substrate by optimizing electrostatic
interactions to allow reversible planar movement. We demonstrate the
imaging of both macroscale and in situ nanoscale
nanoligand movement by magnetically attracting charged nanoligand
to manipulate macroscale ligand density. We show that in situ magnetic control of attracting charged nanoligand facilitates stem
cell adhesion, both in vitro and in vivo, with reversible control. Furthermore, we unravel that in
situ magnetic attraction of charged nanoligand stimulates
mechanosensing-mediated differentiation of stem cells. This remote
controllability of ECM-mimicking reversible ligand variations is promising
for regulating diverse reparative cellular processes in vivo.
Natural extracellular matrix (ECM) can regulate the interactions between cells and ligands by exhibiting heterogeneous nano-sequences periodically displaying adhesive ligands, such as RGD ligand in vivo. [1,2] Cell-adhesive ECM proteins, such as fibronectin, vitronectin, and collagen, were shown to form periodically sequenced RGD ligand-bearing nanostructures (67-100 nm). [1] Periodic structure in reflectance was also observed from native tissues. [2] The ligation of integrin with adhesive ligand mediates the assembly of cytoskeletal actin filaments and focal adhesion (FA) complexes to activate mechanosensing signaling pathways that can regulate cellular differentiation. [3,4] Strategically developing materials with heterogeneously sequenced ligand nanostructures can emulate ECM [5] microenvironment to help elucidate the interactions between cells and nano-ligands with tunable frequency and sequences. This can effectively regulate diverse cellular adhesion and functionality in vivo, such as FA, mechanosensing, and differentiation of stem cells. [6] The native extracellular matrix (ECM) can exhibit heterogeneous nanosequences periodically displaying ligands to regulate complex cell-material interactions in vivo. Herein, an ECM-emulating heterogeneous barcoding system, including ligand-bearing Au and ligand-free Fe nano-segments, is developed to independently present tunable frequency and sequences in nano-segments of cell-adhesive RGD ligand. Specifically, similar exposed surface areas of total Fe and Au nano-segments are designed. Fe segments are used for substrate coupling of nanobarcodes and as ligand-free nanosegments and Au segments for ligand coating while maintaining both nanoscale (local) and macroscale (total) ligand density constant in all groups. Low nano-ligand frequency in the same sequences and terminally sequenced nano-ligands at the same frequency independently facilitate focal adhesion and mechanosensing of stem cells, which are collectively effective both in vitro and in vivo, thereby inducing stem cell differentiation. The Fe/RGD-Au nanobarcode implants exhibit high stability and no local and systemic toxicity in various tissues and organs in vivo. This work sheds novel insight into designing biomaterials with heterogeneous nano-ligand sequences at terminal sides and/or low frequency to facilitate cellular adhesion. Tuning the electrodeposition conditions can allow synthesis of unlimited combinations of ligand nano-sequences and frequencies, magnetic elements, and bioactive ligands to remotely regulate numerous host cells in vivo.
Synthesis of TiO2 nanoparticle through hydrolysis method is presented followed by TiO2nanoparticle doped polyvinyl alcohol nanocomposite by solution process. FTIR, XRD, DSC-TGA, FESEM, TEM analysis are used to identify the nature of synthesized nanoparticle and loading uniformity of developed composite material. A simple modified clad based optical fibre sensor is developed to measure relative humidity. Coated modified clad optical fibre exhibits excellent relative humidity sensing performance with improved thermal stability of coating material in wide range of 9-95 % RH with good process repeatability. Sensor response is also observed to be very fast and highly reversible. Advantage of our developed composite material become evident when it exhibits wider range of moisture sensitivity compare to pure PVA or pure TiO2 material found in literature. Performance of PVA-TiO2 nanocomposite thick film is also evaluated by capacitance method and result found to agree with coated modified clad optical fibre.
The development of materials capable of varying macroscale ligand distributions can emulate an extracellular matrix (ECM) remodeling and regulate the adhesion and polarization of macrophages. In this report, negatively charged slidable nano‐ligands are assembled and then conjugated to a positively charged substrate via electrostatic interaction. The negatively charged slidable nano‐ligands are prepared by coating magnetic nanoparticles with a polymer linker and negatively charged RGD ligand. The nano‐ligand sliding is characterized under an external magnetic field, which spatiotemporally alters macroscale ligand density. To the best of knowledge, this is the first demonstration that magnetic maipulation of the macroscale ligand density inhibits inflammatory M1 phenotype but stimulates the adhesion and regenerative M2 phenotype of host macrophages. Furthermore, it is elucidated that the magnetic attraction of the slidable nano‐ligand facilitates the assembly of adhesion structures in macrophages, thereby stimulating their regenerative M2 phenotype. The design of ECM‐emulating materials that allow remote, spatiotemporal, and reversible controllability of macroscale ligand density provides an appealing strategy in the spatiotemporal regulation of immunomodulatory tissue‐regenerative responses to implants in vivo.
Macrophages
can associate with extracellular matrix (ECM) demonstrating
nanosequenced cell-adhesive RGD ligand. In this study, we devised
barcoded materials composed of RGD-coated gold and RGD-absent iron
nanopatches to show various frequencies and position of RGD-coated
nanopatches with similar areas of iron and RGD-gold nanopatches that
maintain macroscale and nanoscale RGD density invariant. Iron patches
were used for substrate coupling. Both large (low frequency) and externally
positioned RGD-coated nanopatches stimulated robust attachment in
macrophages, compared with small (high frequency) and internally positioned
RGD-coated nanopatches, respectively, which mediate their regenerative/anti-inflammatory
M2 polarization. The nanobarcodes exhibited stability in vivo. We shed light into designing ligand-engineered nanostructures in
an external position to facilitate host cell attachment, thereby eliciting
regenerative host responses.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.