Initial results en route toward construction of complex magnetic core-shell silica and organosilica nanotheranostics are presented. Magnetite nanoparticles are synthesized by three different methods and embedded within mesoporous silica and organosilica frameworks by different surfactant-templated procedures to produce three types of core-shell nanoparticles. Magnetite nanoparticles (15 nm in diameter) are embedded within mesoporous silica nanoparticles to produce cell-like material with predominantly one magnetite nuclei-resembling core per nanoparticle, with final particle diameter of ca. 150 nm, specific surface area of 573 m2/g and hexagonally structured tubular pores (2.6 nm predominant diameter), extended throughout the volume of nanoparticles. Two forms of spherical core-shell nanoparticles composed of magnetite cores embedded within mesoporous organosilica shells are also obtained by employing ethylene and ethane bridged organobisalkoxysilane precursors. The obtained nanomaterials are characterized by high surface area (978 and 820 m2/g), tubular pore morphology (2 and 2.8 nm predominant pore diameters), different diameters (386 and 100-200 nm), in case of ethylene- and ethane-composed organosilica shells, respectively. Different degree of agglomeration of magnetite nanoparticles was also observed in the obtained materials, and in the case of utilization of surfactant-pre-stabilized magnetite nanoparticles for the syntheses, their uniform and non-agglomerated distribution within the shells was noted.

Diatoms represent a natural source of mesoporous silica whose applications range from biomedical to photonic fields. Porous hierarchically organized micro structures, the biosilica shells called frustules, can be obtained by removal of the organic biological matter from the unicellular living algae. Diatoms frustules have been investigated as scaffold for bone tissue growth taking advantage of their nanostructured surface and of the possibility to chemically modify the biosilica. Here we report on an easy way to calcium-doped biosilica supports for bone tissue regeneration by in vivo feeding the algae. FTIR and EDX analyses confirmed the incorporation of calcium into the mesopouros biosilica. Cell viability studies showed an ameliorative effect on the Saos-2 cells spreading compared with the cells grown on non-doped biosilica supports.

Human dental pulp stem cells (DPSCs) can differentiate, showing potential for regenerative medicine. Designing artificial surfaces with properties appropriate for the initiation of extracellular matrix (ECM) adsorption and organization is a critical step in tissue engineering and can greatly impact protein adhesion. Sulfonated polystyrene (SPS), used as a scaffold for tissue development, stimulates protein adsorption due to the increased negative charge of sulfonate.

Graphene and graphene oxide (GO) sheets enhance stem cell growth and differentiation because they are soft membranes with “high in-plane” stiffness and have the potential to be transferable and implantable platforms. This project functionalized GO and reduced GO (RGO) with gold or silver nanoparticles, mixing with SPS to investigate their combined impact on DPSC differentiation and protein adsorption, hypothesizing that this combination supplies more charges to better absorb the proteins to the surface and stimulate differentiation.

Results indicate that proteins of cells plated on the gold-RGO/SPS surfaces were the most highly adsorbed and most densely packed. Additionally, the cell moduli data indicated that the metal-RGO solutions substantially induced a change in modulus even more than Dexamethasone, a glucocortoid known to enhance this process in DPSCs. This suggests that the metal-RGO solutions may be instrumental in osteogenic induction.

In recent years, tissue engineering has been utilized as an alternative approach to organ transplantation. Success rate of tissue regeneration influenced by the biomaterials, cell sources, growth factors and scaffold fabrication. Design and precise fabrication of scaffolds are required to support cells to expand and migrate to 3D environment. Common scaffold fabrication techniques use heat, adhesives, molds or light. In this research, “inverse-photolithography” which is a light based fabrication technique was used to generate the scaffolds. In order to control the interior architecture of the scaffold “a single vertical strut” and “a y-shape” were fabricated with the 3D printer by using the dissolvable filament. Then, the strut and the y-shape were immersed into the photo-curable solution which is poly(ethylene glycol) diacrylate (PEGDA) and photo-initiator mixture. UV light with the 365nm wavelength was placed up-side down under the solution. Photo-curable mixture was exposed to the UV light for 3 minutes to cure the entire scaffold. Solidified scaffold with the strut and y-shape inside was kept in the limonene solution. Limonene penetrated through the open ended strut and y-shape and it dissolved the 3D printed strut and y-shape away leaving the fabricated PEGDA based scaffolds. This preliminary research showcases, the 3D scaffolds with the controlled interior design, can be fabricated with the “inverse-photolithography” technique.

Herein, we demonstrate a facile, rapid, and scalable method to fabricate polymer-based gratings for surface-enhanced Raman spectroscopy (SERS) sensors. To accomplish this, epoxy nanostripe arrays on silicon substrates were prepared using thermal annealing and UV-cross-linking. After preparation of the nanostripe arrays, the surface was briefly treated with oxygen plasma, which decreased the surface energy and enabled the growth of AgNPs on the polymer surface using a simple, low-cost, aqueous-based synthesis procedure. The SERS substrates exhibited a detection limit of ∼1 pM using rhodamine 6G (R6G). In addition, preliminary work with E. coli DH5 showed that the nanoimprinted substrates can be used to obtain Raman spectra of washed bacteria cells.

Medical products comprised of devices and drugs have been known as a combination product. The biodegradable collagen (Col) sponges impregnated with recombinant human bone morphogenetic protein can make bone formation hasten. It is expected further features by a combination of various growth factors and artificial bone materials. The binding properties of such factors to Col and hydroxyapatite (HAp) have not been elucidate to achieve a controlled release. In this study, we investigated artificial periosteum-like membranes made from tilapia fish Col and HAp composites as a drug carrying support. The Col-HAp composites with three different compositions in weight ratio of 2:8, 5:5 and 8:2 were made and crosslinked by irradiation of gamma-ray in wet condition. The tensile strengths of the membranes in wet or dry were depended on the compositions; however the strengths of the membranes in wet were apparently weaker at 1/10 or less than those in dry at a maximum 90 MPa. The adsorption ability of proteins, bovine serum albumin (BSA) or lysozyme (LSZ), on the membranes exhibited different tendency; the membranes including higher weight ratio of HAp adsorbed BSA rather than LSZ. These results indicated that the artificial Col-HAp membranes would be the suitable materials for biomedical device as combination products.

The kinetics of silver nanoparticles release from chitosan spheres is addressed experimentally and theoretically in this work. From the experimental viewpoint, the study of silver nanoparticles release is performed by measuring the time-dependent UV-Vis spectra of solutions where spheres were dispersed. The UV-VIS spectra intensity reflects the concentration of nanoparticles in the solution. Despite simple expressions for drug release are found in the literature, as those that relate the amount of drug release with the square root of time, a proper modeling might require the inclusion of several phenomena such as the presence of stagnant layers, swelling or erosion of the matrix, accumulation of particles in the medium, amongst others. The experiments show that chitosan/silver nanoparticles complexes are actually released, indicating that both swelling and erosion of the matrix takes place during the release process. The simplest model for drug release, i.e., the Higuchi’s model, fits the observed results surprisingly well, which is a relevant result due to the lack of mathematical modeling for the release of nanoparticles.

Surfactant-free oil-in-water-in-oil (O/W/O) emulsions were successfully prepared through a facile approach using natural ingredients (biopolymers and crystalline fat particles) as stabilizers. Microstructure (PLM, cryo-SEM and confocal microscopy) and diffusive NMR studies revealed that emulsions with ultra-high loading of internal oil droplet phase with high storage stability could be easily prepared in absence of low-molecular weight synthetic surfactants. The internal oil droplets were stabilized by the presence of interfacial layers of gelled biopolymers while the encased water droplets were stabilized by a combination of interfacial crystal accumulation (Pickering stabilization) and network stabilization created by bulk crystallization of fat particles. Small (oscillatory shear rheology) and large (force-displacement measurements) deformation studies were used to gain important insights into the ‘structure-properties’ links. Furthermore, on monitoring the stability of these emulsions in terms of droplet size changes and diffusion of the internal oil phase (over a period of 3 months), they showed exceptional stability with absence of any droplet coalescence and minimal oil diffusion to the external phase. Such complex colloids stabilized by natural ingredients could find important industrial applications in development of novel products in bio-related fields of pharmaceuticals, cosmetics and foods.

Lignocellulosic biofuels have been identified as a possible solution to contribute to the world’s demands in energy and environmental sustainability. However, the fundamental understanding of the physical and chemical traits hindering key reactions during biomass to biofuel conversion processes has been limited by the lack of suitable tools and by the large natural variability in such systems. Reaction wood constitutes a good model system to study variations of cellulose content, given the increase in cellulose content in the cell walls of the region under tension in the plant during growth. In this work, we use confocal Raman mapping and Pulsed Force Mode Atomic Force Microscopy (PFM) to explore the effect of variation in cellulose content on the structure and composition of the plant cell wall at the nanoscale. Using statistical analysis on Raman datasets, the characteristic peaks for cellulose and lignin are examined to reveal changes in peak positions across the different scanned regions of the cross section. PFM is used to study local mechanical properties of the different layers of the cell wall. Our approach facilitates the correlation of structure-composition traits of the plant cell wall for a more fundamental understanding of processes involved in biofuel research.

We fabricated a novel open-air channel with high efficient capillary-driven system inspired by a coastal animal “wharf roach”. The animal has open-air channels on its legs to transport water spontaneously using by capillary force. We abstracted principles controlling this phenomenon and applied it to artificial open-air channels, aiming at manipulating liquids without external energies. After surface modification for high surface free energy, the inspired open-air channels were able to transport water against gravity as well as the open-air channels of wharf roach by capillary effect of surface microstructures and chemistries. Topographical variation in micrometer-scaled patterns induced transport velocities improvement due to the enhancement of spreading intervals between the microstructure and wettability. Considering topography of micropatterned surfaces, the open-air channels with controllable transport velocity are applicable to capillary-driven microfluidics and lab-on-a-chips.

Insects are recognized with their ability to efficiently move, operate, and function, and hence are inspiration for the design of micromechanical systems. This work deals with the structural, mechanical, and frictional characterization of the leg joint articulations of the katydid (Orthoptera: Tettigoniidae). For the katydids, the tibia joints were found to show a nanosmooth texture while the femur joint had a micro/nanotextured surface characteristics. The nanotexture was a two-tone periodic patterns with the hierarchical structures involving cylindrical ridges that are covered with nanoscale lamellar patterns perpendicular to the long axis and valleys between ridges that are decorated with the hillock patterns. The tibia and femur contact regions showed the reduced elastic modulus (E r) values ranging from 0.88 ± 0.01 GPa to 3.90 ± 0.11 GPa. The friction coefficient (μ) value of 0.053 ± 0.001 was recorded for the sliding contact of the tibia joint against the femur joint in air under dry conditions. The low friction values are attributed to the reduced real area of contact between the joint pair due to the coupling of the nanosmooth surfaces against the hierarchically nanotextured surfaces.

Inspired by sea sponges, porous Al2O3/starch composite sponges were designed and fabricated as a new controlled release system enabling mechano-triggered logic delivery of molecules. Results of material characterization indicate that the all the composite sponges had a high macro-porosity of >80%, and dehydrated sponges revealed favorable pore structure for drug loading and retaining. The composite sponges have moisture-dependent mechanical properties and samples with appropriate moisture contents revealed high resilience and mechanical robustness under cyclic deformation. Based on the unique mechanical properties of the composite sponge, mechanically modulated, nano-gram precision delivery of model molecules was achieved in an AND logic manner gated by both moisture and compressive strain.