Shape-dependent antimicrobial activities of silver nanoparticles.

Purpose: An important application of silver nanoparticles (Ag NPs) is their use as an antimicrobial and wound dressing material. The aim of this study is to investigate the morphological dependence on the antimicrobial activity and cellular response of Ag NPs. Materials and methods: Ag NPs of various shapes were synthesized in an aqueous solution using a simple method. The morphology of the synthesized Ag NPs was observed via TEM imaging. The antimicrobial activity of the Ag NPs with different morphologies was evaluated against various microorganisms (Escherichia coli [E. coli], Staphylococcus aureus [S. aureus], Pseudomonas aeruginosa [P. aeruginosa]). The antimicrobial activity of the Ag NPs was also examined according to the concentration in terms of the growth rate of E. coli. Results: The TEM images indicated that the Ag NPs with different morphologies (sphere, disk and triangular plate) had been successfully synthesized. The antimicrobial activity obtained from the inhibition zone was in the order of spherical Ag NPs > disk Ag NPs > triangular plate Ag NPs. In contrast, fibroblast cells grew well in all types of Ag NPs when the cell viability was evaluated via an MTT assay. An inductively coupled plasma mass assay showed that the difference in the antimicrobial activities of the Ag NPs was closely associated with the difference in the release rate of the Ag ions due to the difference in the surface area of the Ag NPs. Conclusion: The morphological dependence of the antimicrobial activity of the Ag NPs can be explained by the difference in the Ag ion release depending on the shape. Therefore, it will be possible to control the antimicrobial activity by controlling the shape and size of the Ag NPs.

Nasal versus oral midazolam sedation for pediatric dental patients.

PURPOSE: The purpose of this study was to evaluate and compare intranasal (IN) and oral (PO) midazolam for effect on behavior, time of onset, maximum working time, efficacy, and safety for patients requiring dental care. METHODS: Forty anxious subjects (20 IN, 20 PO, Frankl Scale 3 and 4, ages 2-6 years, ASA I and II) were sedated randomly with either IN (0.3 mg/kg) or PO (0.7 mg/kg) midazolam. The dental procedure under sedation was videotaped and rated by a blinded and calibrated evaluator using Houpt's behavior rating scale. RESULTS: There was no statistical difference for overall behavior (F3,27 = 0.407; P = .749). The planned contrasts showed significant interactions between time and route (IN vs PO) between 25 and 30 minutes after starting sedation. The time of onset (P = .000) and the working time (P = .007) were significantly different between IN and PO midazolam. There were no statistically significant differences in vital signs (O2 sat, HR, RR, BP) between PO and IN (P = .595). IN subjects showed more movement and less sleep toward the end of the dental procedures, and faster onset time but shorter working time than PO. Vital signs were stable throughout the procedures with no significant differences. CONCLUSIONS: Mean onset time was approximately 3 times faster with IN administration compared to PO administration. Mean working time was approximately 10 minutes longer with PO administration than it was with IN administration. Overall behavior under PO and IN was similar. However, more movement and less sleep were shown in subjects under IN than those under PO toward the end of the dental session. All vital signs were stable throughout the procedures and showed no significant differences between PO and IN administration.