Reality Check for Nanomaterial‐Mediated Therapy with 3D Biomimetic Culture Systems

The recent progresses in tissue engineering and nanomaterial‐based therapeutics/theranostics have led to the ever increasing utilization of 3D in vitro experimental models as the bona fide culture systems to evaluate the therapeutic/theranostic effects of nanomedicine. Compared to the use of conventional 2D culture platforms, 3D biomimetic cultures offer unmatched advantages as relevant physiological and pathological elements can be incorporated to allow better characterization of the engineered bio‐nanomaterials in the targeted tissue‐specific microenvironment. In this Feature Article, the current state‐of‐the‐art 3D in vitro models that have been developed for the evaluation of biosafety and efficacy of nano‐ therapeutics/theranostics targeting the colon, blood–brain barrier (BBB), lungs, skin tumor models to bridge the nanomedicine bench to pre‐clinical ravine are reviewed. Furthermore, the critical physicochemical parameters of the bio‐nanomaterials that govern its transport and biodistribution in a complex 3D microenvironment will be highlighted. The major challenges and future prospects of evaluating nanomedicine in the third dimension will also be discussed.     

Irreversible pressure-induced transformation of boron nitride nanotubes

We have used Raman spectroscopy to study the behavior of multi-walled boron nitride nanotubes and hexagonal boron nitride crystals under high pressure. While boron nitride nanotubes show an irreversible transformation at about 12 GPa, hexagonal boron nitride exhibits a reversible phase transition at 13 GPa. We also present molecular dynamics simulations which suggest that the irreversibility of the pressure-induced transformation in boron nitride nanotubes is due to the polar nature of the bonds between boron and nitrogen.     

Double-walled carbon nanotubes under hydrostatic pressure: Raman experiments and simulations

We have used Raman spectroscopy to study the behavior of double-walled carbon nanotubes (DWNT) under hydrostatic pressure. We find that the rate of change of the tangential mode frequency with pressure is higher for the sample with traces of polymer compared to the pristine sample. We have performed classical molecular dynamics simulations to study the collapse of single (SWNT) and double-walled carbon nanotube bundles under hydrostatic pressure. The collapse pressure (pc) was found to vary as 1/R3, where R is the SWNT radius or the DWNT effective radius. The bundles showed approximately 30% hysteresis and the hexagonally close packed lattice was completely restored on decompression. The pc of a DWNT bundle was found to be close to the sum of its values for the inner and the outer tubes considered separately as SWNT bundles, demonstrating that the inner tube supports the outer tube and that the effective bending stiffness of DWNT, D(DWNT) - 2D(SWNT).     

The Influence of the Thickness and Areal Density on the Mechanical Properties of Carbon Fibre Reinforced Aluminium Laminates (CARAL)

A novel composite material consisting of a laminate of several thin aluminium sheets bonded with layers of carbon fibre mat/epoxy resin. Carbon fibre reinforced aluminium laminates (CARAL) offer specific advantageous properties such as better strength, fatigue, impact, corrosion resistance, fire resistance and weight savings. CARAL is a kind of fibre metal laminate system. In the present work, CARAL was prepared and experimental tests were conducted to evaluate the influence of the thickness and areal density on the mechanical properties of CARAL. Mechanical properties such as, the tensile strength and flexural strength of the laminates were increased with the increase in thickness and areal density. CARAL with four aluminium layers and three carbon fibre mat layers have superior strength than the laminates with lesser number of layers due to thickness of laminates and areal density.     

Synthesis and characterization of biodegradable poly (ethylene glycol) and poly (caprolactone diol) end capped poly (propylene fumarate) cross linked amphiphilic hydrogel as tissue engineering scaffold material

Biodegradable poly (caprolactone diol-co-propylene fumarate-co-ethylene glycol) amphiphilic polymer with poly (ethylene glycol) and poly (caprolactone diol) chain ends (PCL-PPF-PEG) was prepared. PCL-PPF-PEG undergoes fast setting with acrylamide (aqueous solution) by free radical polymerization and produces a crosslinked hydrogel. The cross linked and freeze-dried amphiphilic material has porous and interconnected network. It undergoes higher degree of swelling and water absorption to form hydrogel with hydrophilic and hydrophobic domains at the surface and appreciable tensile strength. The present hydrogel is compatible with L929 fibroblast cells. PCL-PPF-PEG/acrylamide hydrogel is a candidate scaffold material for tissue engineering applications.     

Preparation and Properties of Cellulose/Tamarind Nut Powder Green Composites

Using biopolymer cellulose as the matrix and tamarind nut powder (TNP) obtained from agricultural waste of tamarind nuts as the filler, the green composites were made. Cellulose was dissolved in environmental friendly solvent of aq. 8 wt. % Lithium hydroxide and 15 wt. % urea which was precooled to ?12 ° C. To the cellulose solutions, TNP was added in 5 wt. % to 25 wt. % of cellulose separately. Each solution was evenly spread on glass plates and the wet composites were prepared by regeneration method using ethyl alcohol coagulation bath. The wet films were dried in air at room temperature. The dried composite films were characterized by FTIR spectroscopy, X-ray diffraction, thermogravimetric analysis and also tested for their tensile properties. The tensile strength and the % elongation at break of the composites were higher than those of the matrix and increased with TNP content. While the matrix had a tensile strength of 111.8 MPa, the cellulose/TNP composite loaded with 25 wt.% TNP possessed a tensile strength of 125.4 MPa (12% increase). Though the thermal stability of the composites was lower than cellulose matrix, all the composites were stable up to a temperature of 350 °C.     

Small upconverting fluorescent nanoparticles for biomedical applications

Fluorescent labels have been widely used for biological applications, primarily in imaging and assays. Traditional fluorophores such as fluorescent dyes are mainly based on downconversion fluorescence, which have several drawbacks such as photobleaching, high background noise from autofluorescence, and considerable photodamage to biological materials. Upconverting fluorescent nanoparticles emit detectable photons of higher energy in the near-infrared (NIR) or visible range upon irradiation with an NIR light in a process termed 'upconversion.' They overcome some of the disadvantages faced by conventional downconversion labels, thus making them an ideal fluorescent label for biological applications. This review looks at the development of these particles, critically examines the reported applications, and discusses their future in biomedicine.     

Polymerization of Diphenylcarbodiimide Catalysed by Fullerene-60

In the presence of fullerene-60 as a catalyst, the formation of diphenylcarbodiimide (DPCD) from phenylisocyanate followed by its polymerization into a hexamer in xylene at refluxing temperature was carried out. The product was analysed by FAB-Mass spectrometry, FT-IR, UV-Vis and HPLC techniques.     

A SiC MEMS Resonant Strain Sensor for Harsh Environment Applications

In this paper, we present a silicon carbide MEMS resonant strain sensor for harsh environment applications. The sensor is a balanced-mass double-ended tuning fork (BDETF) fabricated from 3C-SiC deposited on a silicon substrate. The SiC was etched in a plasma etch chamber using a silicon oxide mask, achieving a selectivity of 5:1 and etch rate of 2500 Aring/min. The device resonates at atmospheric pressure and operates from room temperature to above 300degC. The device was also subjected to 10 000 g shock (out-of-plane) without damage or shift in resonant frequency. The BDETF exhibits a strain sensitivity of 66 Hz/muepsiv and achieves a strain resolution of 0.11 muepsiv in a bandwidth from 10 to 20 kHz, comparable to state-of-the-art silicon sensors     

Prediction of Heat of Vapourization of Moisture from Cereal Grains - A Modelling Approach

The Henderson's EMC model in modified form was used to fit the EMC data given by Engels et al (1987) for brown, parboiled rice. The constants in the model were related to temperature. A method to find an expression for heat of vapourization of moisture from grain was developed and demonstrated using the EMC data of brown, parboiled rice. The heat of vapourization of moisture from rice was high at low moisture contents. For moisture contents above 25% (db), the moisture inside the grain behaved almost like free water.