Preparation of novel antimicrobial-modified starch and its adsorption on cellulose fibers: Part I. Optimization of synthetic conditions and antimicrobial activities

Abstract

Antimicrobial-modified starch was synthesized by covalently bonding guanidine polymer (PHGH) with potato starch via coupling reaction. Orthogonal tests were applied to optimize the reaction conditions. The coupling efficiency could reach 90.21% at the optimal conditions: temperature, 70°C; time, 2 h; PHGH/starch, 120 wt.%; GDE/ starch, 8 wt.%; pH, 11. PHGH modified starches exhibited high antimicrobial activities against both E. coli and S. aureus. Shaking flask method was more suitable for current non-released modified starches than diffusion method to evaluate the antimicrobial activities. In the presence of 1.0 wt.% PHGH in wood fibers, the growth inhibition reached almost 100%. The AFM results also demonstrated that the antimicrobial mechanism of PHGH was to destroy the membrane of the cells.

Coating PHGH-Modified Starch on Papers to Induce Antimicrobial Properties

“…The significant losses of intracellular components from the bacterial cells caused the membrane to collapse, leading to a reduction in height to 100 nm. This was consistent with the previous findings (Guan et al 2007(Guan et al , 2008aZiaee et al 2010). The cell membrane of E. coli is composed of proteins and phospholipids.…”

“…Potato starches, glycerol diglycidyl ether (GDE), Luria-Bertani (LB) broth, LB agar, and phosphate buffered saline (PBS,pH 7.4) were all purchased from Sigma-Aldrich. Poly(hexemethylene guanidine hydrochloride) (PHGH) was synthesized according to the procedures described in previous work (Guan et al 2008a). …”

“…To create branched antimicrobial polymers, PHGH was grafted onto starch according to Guan et al (2008a). Initially, 2.4 g of GDE was added dropwise within 20 min to 200 mL of starch solution (10%, aqueous), while the pH was adjusted to 10 using 1 N NaOH.…”

“…After 30 min of reaction, 8 g of PHGH was added to the solution. The reaction continued prior to neutralizing with HCl (Guan et al 2008a). The grafting percentage of PHGH onto the starch was determined using a thermo-gravimetric analyzer (TGA) SDT Q600 (TA instruments, New Castle, DE, United States).…”

Fungicidal activity of AKWATON and in vitro assessment of its toxic effects on animal cells

“…Some studies have shown a fungicidal activity of PHMGH, but so far the mechanism has not been clearly understood. Guan et al (2008) stated that chemical products such as PHMGH act by destroying the plasma membrane of micro-organisms. Koffi-Nevry et al (2011) assessed the antifungal activities of a PHMGH-based disinfectant against 30 strains of fungi isolated from papaya.…”