Antibacterial polycaprolactone electrospun fiber mats prepared by soluble eggshell membrane protein–assisted adsorption of silver nanoparticles

Abstract

Antibacterial polycaprolactone (PCL) electrospun fiber mats were prepared by coelectrospinning PCL with soluble eggshell membrane protein (SEP) in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP), followed by adsorption of silver nanoparticles (Ag NPs) through hydrogen-bonding interaction between the amide groups of SEP and the carboxylic acid groups capped on the surfaces of Ag NPs. The PCL/SEP fiber mat was characterized by X-ray photoelectron spectroscopy, indicating the presence of some SEP on the fiber surface. The adsorption of Ag NPs was confirmed by transmission electron microscopy and quantitatively characterized by thermogravimetric analysis. The pH value of the silver sol used for adsorption is very important in view of the amount and dispersion state of Ag NPs adsorbed on the fibers. The Ag NP-decorated PCL/SEP fiber mats prepared at pH 3-5 exhibit strong antibacterial activity against both gram-negative Escherichia coli and gram-positive Bacillus subtilis. Antibacterial PCL fiber mats were also obtained similarly with the assistance of collagen (another protein) instead of SEP, showing that protein-assisted adsorption of Ag NPs is a versatile method to prepare antibacterial electrospun fiber mats.

Antibacterial thermoplastic polyurethane electrospun fiber mats prepared by 3-aminopropyltriethoxysilane-assisted adsorption of Ag nanoparticles

“…The time to the steady level is 5 h for B. sub. Similar trend was reported for Ag NP-decorated PCL/SEP fiber mats [24] . The antibacterial rates of Ag NP-decorated TPU/5% APS fiber mats prepared at pH = 3, 4 and 5 are summarized in Fig.…”

“…Coordination between Ag NPs and the lone pair of electrons of amino groups may also occur [35] , but is thought of minor importance because with the as-prepared silver sol at pH of 9.7 only few Ag NPs were adsorbed on TPU/5% APS fiber mat. Neat TPU fiber mat hardly adsorbs Ag NPs at pH of 9.7 and does adsorb a small amount of Ag NPs at pH = 3−5 because of the hydrogen-bonding interaction between the urethane or ester groups of TPU and the carboxyl groups capped on Ag NPs, similar to the case of PCL fibers [24] . Figure 4 shows the time course of Ag NP-decorated TPU/APS and Ag NP-decorated TPU fiber mats obtained at pH = 4 against E. coli and B. sub.…”

“…sub., revealing that the functionalization by APS can indeed increase the antibacterial performance of TPU fiber mat. Polymer nanocomposites containing Ag NPs usually show good antibacterial properties because of the excellent antibacterial activity of Ag NPs [24,36,37] . Compared with Ag NP-decorated nylon 6 fiber mat [36] and Ag NP-decorated PCL/SEP fiber mat [24] , the Ag NP-decorated TPU/APS fiber mats prepared in this work show similar performance against E. coli, and no colony of viable bacteria was found at a contact time of 2 h, although the Ag NP-adsorption mechanism is different.…”

“…The aqueous silver sol containing Ag NPs was prepared using the chemical reduction method reported in a previous work [24] . NaBH 4 was used as the reducing agent, while Na 3 C 6 H 5 O 7 ·2H 2 O was used as the stabilizing agent in the process.…”

“…The adsorption of Ag NPs onto the TPU/APS electrospun mats was achieved by filtration method [24,31] . 10 mL of silver sol adjusted freshly to pH = 3.0 or 4.0 or 5.0 by adding dropwise 1 mol/L HCl was filtered through the mat supported by an ordinary filter paper placed in a filtration funnel with diameter of 3 cm.…”