Mach-Zehnder interferometer based integrated-photonic acetone sensor approaching the sub-ppm level detection limit.

The detection of acetone in the gaseous form in exhaled breath using an integrated sensor can provide an effective tool for disease diagnostics as acetone is a marker for monitoring human metabolism. An on-chip acetone gas sensor based on the principle of Mach-Zehnder interferometer is proposed and demonstrated. The sensing arm of the device is activated with a composite film of polyethyleneimine and amido-graphene oxide as the gas-sensitive adsorption layer. The composite film demonstrates good selectivity to acetone gas, can be used repeatedly, and is stable in long-term use. Room temperature operation has been demonstrated for the sensor with high sensitivity under a 20 ppm acetone environment. The detection limit can reach 0.76 ppm, making it feasible to be used for the clinical diagnosis of diabetes and the prognosis of heart failure.

Electrophoretic deposition of collagen/chitosan films with copper-doped phosphate glasses for orthopaedic implants.

Coatings with bioactive properties play a key role in the success of orthopaedic implants. Recent studies focused on composite coatings incorporating biocompatible elements that can increase the nucleation of hydroxyapatite (HA), the mineral component of bone, and have promising bioactive and biodegradable properties. Here we report a method of fabricating composite collagen, chitosan and copper-doped phosphate glass (PG) coatings for biomedical applications using electrophoretic deposition (EPD). The use of collagen and chitosan (CTS) allows for the co-deposition of PG particles at standard ambient temperature and pressure (1 kPa, 25 °C), and the addition of collagen led to the steric stabilization of PG in solution. The coating composition was varied by altering the collagen/CTS concentrations in the solutions, as well as depositing PG with 0, 5 and 10 mol% CuO dopant. A monolayer of collagen/CTS containing PG was obtained on stainless steel cathodes, showing that deposition of PG in conjunction with a polymer is feasible. The mass of the monolayer varied depending on the polymer (collagen, CTS and collagen/CTS) and combination of polymer + PG (collagen-PG, CTS-PG and collagen/CTS-PG), while the presence of copper led to agglomerates during deposition at higher concentrations. The deposition yield was studied at different time points and showed a profile typical of constant voltage deposition. Increasing the concentration of collagen in the PG solution allows for a higher deposition yield, while pure collagen solutions resulted in hydrogen gas evolution at the cathode. The ability to deposit polymer-PG coatings that can mimic native bone tissue allows for the potential to fabricate orthopaedic implants with tailored biological properties with lower risk of rejection from the host and exhibit increased bioactivity.

In vitro evaluation of the toxic effects of MgO nanostructure in Hela cell line.

MgO is an attractive choice for carcinogenic cell destruction in photodynamic therapy, as confirmed by manifold analysis. The prime focus of the presented research is to investigate the toxicity caused by morphologically different MgO nanostructures obtained by annealing at various annealing temperatures. Smart (stimuli-responsive) MgO nanomaterials are a very promising class of nanomaterials, and their properties can be controlled by altering their size, morphology, or other relevant characteristics. The samples investigated here were grown by the co-precipitation technique. Toxicity-dependent parameters were assessed in a HeLa cell model after annealing the grown samples at 350 °C, 450 °C, and 550 °C. After the overall characterization, an analysis of toxicity caused by changes in the MgO nanostructure morphology was tested in a HeLa cell model using a neutral red assay and microscopy. The feasibility of using MgO for PDT was assessed. Empirical modelling was applied to corroborate the experimental results obtained from assessing cell viability losses and reactive oxygen species. The results indicate that MgO is an excellent candidate material for medical applications and could be utilized for its potential ability to upgrade conventionally used techniques.