Study on antibacterial activity of silver nanoparticles synthesized by gamma irradiation method using different stabilizers.

Colloidal solutions of silver nanoparticles (AgNPs) were synthesized by gamma Co-60 irradiation using different stabilizers, namely polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), alginate, and sericin. The particle size measured from TEM images was 4.3, 6.1, 7.6, and 10.2 nm for AgNPs/PVP, AgNPs/PVA, AgNPs/alginate, and AgNPs/sericin, respectively. The influence of different stabilizers on the antibacterial activity of AgNPs was investigated. Results showed that AgNPs/alginate exhibited the highest antibacterial activity against Escherichia coli (E. coli) among the as-synthesized AgNPs. Handwash solution has been prepared using Na lauryl sulfate as surfactant, hydroxyethyl cellulose as binder, and 15 mg/L of AgNPs/alginate as antimicrobial agent. The obtained results on the antibacterial test of handwash for the dilution to 3 mg AgNPs/L showed that the antibacterial efficiency against E. coli was of 74.6%, 89.8%, and 99.0% for the contacted time of 1, 3, and 5 min, respectively. Thus, due to the biocompatibility of alginate extracted from seaweed and highly antimicrobial activity of AgNPs synthesized by gamma Co-60 irradiation, AgNPs/alginate is promising to use as an antimicrobial agent in biomedicine, cosmetic, and in other fields.

Radiation synthesis and characterization of hyaluronan capped gold nanoparticles.

Gold nanoparticles (AuNPs) with diameter from 4 to 10nm, capping by hyaluronan (HA) were synthesized using a γ-irradiation method. The maximum absorption wavelengths at 517-525 nm of colloidal AuNPs/HA solutions were measured by UV-vis spectroscopy. The size and size distribution of AuNPs were determined from TEM images. The influence of various factors on the size of AuNPs particularly the concentration of Au3+ and HA, and dose rate were also investigated. Results indicated that higher dose rate and HA concentration favor smaller sizes of AuNPs whereas the size increases with Au3+ concentration. The colloidal AuNPs/HA solution was fairly stable more than 6 months under storage at ambient condition. The AuNPs stabilized by biocompatible HA with the size less than 10nm as prepared can potentially be applied in biomedicines and cosmetics.

Degradation of chitosan in solution by gamma irradiation in the presence of hydrogen peroxide.

Chitosan from squid pens with deacetylation degree (DD) of 70% and average molecular weight (Mw0) 90.5×103 in dilute lactic acid solution containing H2O2 (1%) was effectively degraded by irradiation with gamma 60Co radiation (1.33kGy/h) at doses in the range 4-16kGy. Based on the results of Mw measured by gel permeation chromatography (GPC), it was concluded that there was particularly strong synergy between H2O2 and radiation for degradation at the lower radiation doses studied. Radiation scission yields (Gs) were found out to be 2.2µmol/J and 0.2µmol/J for 5% chitosan with and without 1% H2O2, respectively. The DD of degraded chitosan measured from IR spectra was almost unchanged by the treatment.