61 research outputs found
Recommended from our members
Polymer surface modification for the attachment of bioactive compounds
This paper reviews recent advances in the covalent attachment of bioactive compounds to functionalized polymer surfaces including relevant techniques in polymer surface modification such as wet chemical, organosilanization, ionized gas treatments, and UV irradiation. Methods of analysis of biofunctionalized polymer surfaces, including spectral methods (X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, atomic force microscopy, and others) as well as non-spectral methods (contact angle, dye assays, biological assays, and zeta potential) are also considered. State-of-the-art techniques in covalent conjugation of bioactive compounds to the modified surfaces, such as usage of hydrophilic, bifunctional, and/or branched spacer molecules, are presented. Relevant bioconjugation reagents and chemistries are described and tabulated. Recently reported applications in areas such as biomedicine, biosensors, enzyme reactors, and textiles, all of which utilize a common set of surface bioconjugation techniques to address these diverse needs, are discussed. Finally, challenges to this emerging field of research are critically evaluated
Recommended from our members
Rechargeable antimicrobial surface modification of polyethylene
Polyethylene films were surface modified, to incorporate amine and amide functionalities, and subsequently were evaluated for their ability to recharge the antimicrobial N-halamine structures after contact with sodium hypochlorite, a common food-approved sanitizer. Surfaces were tested for chlorine retention and release, as well as antimicrobial activity against microorganisms relevant to food quality and food safety, including Escherichia coli K-12, Pseudomonas fluorescens, Bacillus cereus, and Listeria monocytogenes. N-Halamine functionalized polyethylene exhibited chlorine rechargeability, maintaining 5 to 7 nmol/cm2 N-halamine structures for six successive charges. The N-halamine functionalized films achieved a 4-log reduction for all organisms tested and maintained a greater than 3-log reduction for four successive uses, suggesting that the modified polyethylene films are capable of providing rechargeable antimicrobial activity. The modified films exhibited antimicrobial activity in aqueous suspensions (P \u3c 0.05) and reduced microbial growth in diluted broth (P \u3c 0.05), suggesting the potential for biocidal action even in the presence of organic matter. Such a rechargeable antimicrobial surface could supplement existing cleaning and sanitation programs in food processing environments to reduce the adhesion, growth, and subsequent cross-contamination of food pathogens, as well as food spoilage organisms
Recommended from our members
Plasma modification of polyolefin surfaces
In order to functionalize the surface of blown low-density polyethylene (LDPE) and cast polypropylene (CPP) films, and ultimately to maximize the attachment of active molecules onto them, the optimum treatment parameters of capacitively-coupled radio-frequency (13.56 MHz) oxygen plasma were investigated by using contact angle, toluidine blue dye assay, X-ray Photoelectron Spectroscopy (XPS) and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR). Contact angle values of LDPE and CPP samples decreased significantly after oxygen plasma treatment. They further decreased as the plasma power level increased. The treatment time had no substantial effect on contact angle value. The optimum treatment conditions for LDPE and CPP films for maximizing carboxyl functionality without causing observable surface changes were found to be 200 W/200 mTorr and 250 W/50 mTorr, respectively, when treated for 3 min. The maximum carboxyl group concentration obtained with LDPE and CPP films were 0.46 and 0.56 nmol/cm2, respectively. The percent of oxygen atoms on the surface of plasma-treated LDPE and CPP films was determined by XPS analysis to be 22.6 and 28.7%, respectively. The ATR-FTIR absorption bands at 1725–1700 cm−1 confirmed the presence of carboxylic acids on LDPE and CPP films. By exposing the plasma-treated sample to air rather than water and treating films repeatedly with oxygen plasma, a higher carboxyl group concentration could be obtained. Copyright © 2008 John Wiley & Sons, Ltd
Recommended from our members
Covalent attachment of lactase to low-density polyethylene films
Polymer films to which bioactive compounds such as enzymes are covalently attached offer potential for in-package processing of food. β-galactosidase (lactase) was covalently attached to surface-functionalized lowdensity polyethylene films. A two-stepwet chemical functionalization introduced 15.7 nmol/cm2 primary amines to the film surface. Contact angle, dye assays, X-ray photoelectron spectroscopy, and appropriate protein assays were used to characterize changes in film surface chemistry after each step in the process of attachment. Glutaraldehyde was used to covalently attach lactase to the surface at a density of 6.0 μg protein per cm2 via reductive amination. The bond between the covalently attached lactase and the functionalized polyethylene withstood heat treatment in the presence of an ionic denaturant with 74% enzyme retention, suggesting that migration of the enzyme into the food product would be unlikely. The resulting polyethylene had an enzyme activity of 0.020 lactase units (LU)/cm2 (approximately 4500 LU/g). These data suggest that enzymes that may have applications in foods can be covalently attached to inert polymer surfaces, retain significant activity, and thus have potential as a nonmigratory active packaging materials
- …