Silver nanoparticles have been used in numerous commercial products, including textiles, to prevent bacterial growth. Meanwhile, there is increasing concern that exposure to these nanoparticles may cause potential adverse effects on humans as well as the environment. This study determined the quantity of silver released from commercially claimed nanosilver and laboratory-prepared silver coated fabrics into various formulations of artificial sweat, each made according to AATCC, ISO and EN standards. For each fabric sample, the initial amount of silver and the antibacterial properties against the model Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria on each fabric was investigated. The results showed that silver was not detected in some commercial fabrics. Furthermore, antibacterial properties of the fabrics varied, ranging from 0% to greater than 99%. After incubation of the fabrics in artificial sweat, silver was released from the different fabrics to varying extents, ranging from 0 mg/kg to about 322 mg/kg of fabric weight. The quantity of silver released from the different fabrics was likely to be dependent on the amount of silver coating, the fabric quality and the artificial sweat formulations including its pH. This study is the unprecedented report on the release of silver nanoparticles from antibacterial fabrics into artificial sweat. This information might be useful to evaluate the potential human risk associated with the use of textiles containing silver nanoparticles.

Here we demonstrate the controllability on morphology of hydrothermal ZnO nanowires through the critical concentration for nucleation. When Zn ion concentration is relatively low, the nucleation process preferentially occurs on the (0001) plane, promoting nanowire growth. In contrast, for relatively high Zn ion concentration, the (101¯0) plane emerges, suppressing nanowire growth. The occurrence of this nucleation competition on the crystal planes as a function of concentration is caused by differences in the critical nucleation sizes between the (0001) plane and the (101¯0) plane. Furthermore, we found that the density of ZnO nanowires trend to decrease with increasing the growth time due to the lateral growth effect. Photoluminescence measurement of ZnO nanowires exhibited that the near band emission peak of 380 nm decreased with decreasing nanowire diameter while the broad emission peak below band gap appears the opposite trend because of surface to volume ratio effect.

Silk sericin (SS) is a by-product of silk production. In order to transform it into value-added products, sericin can be used as biodegradable and pH-responsive building block in drug delivery materials. To this end, amphiphilic substances were synthesized via the conjugation of hydrophobic polylactide (PLA) to the hydrophilic sericin using a bis-aryl hydrazone linker. PLA was esterified with terephthalaldehydic acid to obtain aromatic aldehyde terminated PLA (PLA-CHO). In addition, lysine groups of SS were modified with the linker succinimidyl-6-hydrazinonicotinamide (S-HyNic). Then, both macromolecules were mixed to form the amphipilic proteinpolymer conjugate in buffer-DMF solution. The formation of bis-aryl hydrazone linkages was confirmed and quantified by UV-Vis spectroscopy. SS-PLA conjugates self-assembled in water into spherical multicompartment micelles with a diameter of around 100 nm. Doxorubicin (DOX) was selected as a model drug for studying the pH-dependent drug release from SS-PLA 2 nanoparticles. The release rate of the encapsulated drug was slower than that of the free drug and dependent on pH; faster at pH 5.0 and resulted in a larger cumulative amount of drug released than at physiological pH of 7.4. The SS-PLA conjugate of high PLA branches showed smaller particle size and lower loading capacity than the one with low PLA branches. Both SS-PLA conjugates had negligible cytotoxicity whereas, after loading with DOX, the SS-PLA micelles were highly toxic for the human liver carcinoma immortalized cell line HepG2. Therefore the SS-based biodegradable amphiphilic material showed great potential as a drug carrier for cancer therapy.