Biomedical subjects

S D Worley

Publications and source records attributed to S D Worley.

At least 19 recordsLinked to original sources

PubMed2006

N-halamine biocidal coatings.

Novel N-halamine siloxane and epoxide coatings are described. The coatings can be rendered biocidal by exposure to dilute bleach. Once the bound chlorine is lost from the coatings, it can be regenerated by further exposure to dilute bleach. Synthetic schemes and biocidal efficacy data are presented. The stabilities of the bound chlorine on the surfaces are also addressed. Substrates employed include sand, textiles, and paint. Potential uses for the technology are discussed.

Coated Materials, Biocompatible↗

PubMed2006

Mechanism of formation of biocidal imidazolidin-4-one derivatives: an Ab initio density-functional theory study.

N-halamine chemistry has been a research topic of considerable importance in these laboratories for over 2 decades because N-halamine compounds are very useful in preparing biocidal materials. To understand the utility of these compounds, the stabilities and mechanism of halogenation of cyclic N-halamine compounds should be resolved. The important precursor biocidal compound, 2,2,5,5-tetramethylimidazolidin-4-one (TMIO) was considered as a model in this theoretical study. The thermodynamic and kinetic products of monohalogenation were investigated along with tautomerization of TMIO and succinimide theoretically at the level of B3LYP/6-311+G(2d,p). Solvation effects (water and chloroform) were included using the CPCM solvation model with UAKS cavities. Several mechanisms have been proposed for the chlorine migration from the 3-position (kinetic product) to the 1-position (thermodynamic product) of the TMIO ring. The results are in agreement with experimental NMR data.

Crystallography, X-Ray↗

PubMed2006

Synthesis and antimicrobial applications of 5,5'-ethylenebis[5-methyl-3-(3-triethoxysilylpropyl)hydantoin].

A novel, durable, long lasting, N-halamine siloxane monomer precursor, 5,5'-ethylenebis[5-methyl-3-(3-triethoxysilylpropyl)hydantoin] has been prepared and characterized by (1)H-NMR and FTIR for the purpose of functionalizing the surfaces of various materials. In this work, the precursor N-halamine moiety was attached by siloxane covalent bonding to surfaces of cotton fibers. Simulated laundering tests indicated that the chlorinated N-halamine structure could survive many repeated home launderings. The materials were rendered biocidal after exposure to oxidative halogen solutions, i.e. dilute household bleach. Once chlorinated, these materials were biocidal against Staphylococcus aureus and Escherichia coli. Upon loss of the halogen from either long-term use or consumption by the microbes on the surfaces, they could be simply recharged by further exposure to dilute bleach to regain biocidal activity.

Anti-Infective Agents↗

PubMed2005

N-halamine/quat siloxane copolymers for use in biocidal coatings.

A series of copolymers incorporating N-halamine siloxane and quaternary ammonium salt siloxane units has been prepared. The primary function of the quat units was to render the siloxane copolymers soluble in water. The copolymers have been coated onto cotton swatches and evaluated for biocidal efficacy against Staphylococcus aureus and Escherichia coli O157:H7. It was determined that both N-halamine and quat functional groups were effective against S. aureus, but only the N-halamine units were effective against Escherichia coli O157:H7. The copolymers should be useful for applications for which aqueous media is preferred over organic solvents to be used during coating procedures.

Anti-Bacterial Agents↗

PubMed2000

Synthesis and spectroscopy of N3P3X5OCH=CH2 (X = Cl, F, OCH3, OCH2CF3, N(CH3)2) and N3P3X4(OCH=CH2)2 (X = Cl, N(CH3)2). Correlations of ultraviolet photoelectron spectroscopy and nuclear magnetic resonance data to electronic and geometrical structure.

The syntheses of the vinyloxycyclotriphosphazene derivatives N3P3X5OCH=CH2 (X = OMe, OCH2CF3) and the N3P3(NMe2)4(OCH=CH2)2 isomeric mixture along with improved preparations of N3P3X5OCH=CH2 (X = F, NMe2) are reported. The interactions between the vinyloxy function and the cyclophosphazene in these and the previously reported N3P3Cl5 (OCH=CH2) and N3P3F6-n(OCH=CH2)n (n = 1-4) have been examined by ultraviolet photoelectron spectroscopy (UPS) and NMR spectroscopy. The UPS data for the chloro and fluoro derivatives show a strong electron-withdrawing effect of the phosphazene on the olefin that is mediated with decreasing halogen substitution. The 1H and 13C NMR data for N3P3X5OCH=CH2 (X = F, Cl, OMe, OCH2CF3, NMe2) show significant changes as a function of the phosphazene substituent. There is a linear correlation between the beta-carbon chemical shift on the vinyloxy unit and the phosphorus chemical shift at the vinyloxyphosphorus centers. The chemical shifts of the different phosphorus centers on each ring are also related in a linear fashion. These relationships may be understood in terms of the relative electron donor-acceptor abilities of the substituents on the phosphazene ring. The 1H NMR spectra of the N3P3(NMe2)4(OCH-CH2)2 isomeric mixture allow for assignment of the relative amounts of cis and trans isomers. A model for the observed cis preference in the formation of N3P3Cl4(OCH=CH)2 is presented.

Journal Article↗

PubMed2000

Infection-resistant nonleachable materials for urologic devices.

Bacterial colonization is the primary clinical problem faced by the surgeon and medical device innovator. Despite the absence of effective systemic treatment, medical implants and devices have been deployed with increasing success over the past five decades. Infection-resistant materials (IRMs) are a relatively recent addition to the science of implant and device development. The first IRM utilized leachable antimicrobial agents. Nonleachable technologies are being developed, some of which have the potential to make organ replacement even more successful in the future.

Anti-Bacterial Agents↗

PubMed1997

Inactivation of rotavirus by new polymeric water disinfectants.

Two new insoluble polymeric materials were evaluated for their efficacies in inactivating rotavirus in flowing water in a biocidal filter application. The two polymers are N-chloro and N-bromo derivatives of a poly-styrene hydantoin prepared from commercial poly-styrene. The studies were conducted for rotavirus in halogen demand-free water at pH 7.0, 25 degrees C and Environmental Protection Agency (EPA) Test Water no. 2 at pH 9.0, 4 degrees C which contained heavy halogen demand. The range of flow rates studied was 0.16-1.22 ml s-1 corresponding to contact times in the range of 4-24 s. Both of the polymers were effective in inactivating rotavirus, the N-bromo derivative providing a 4-6 log reduction under the test conditions. The materials may be useful as supplemental filters for hand-held water purification units.

Disinfectants↗

PubMed1994

Interaction of methyl benzoate as a model odorant with a series of free-base amino acids and some amino-acid hydrochlorides.

The interactions of methyl benzoate as a model odorant with a series of free-base amino acids: lysine, tryptophan, arginine, proline, histidine, cysteine, leucine, threonine and phenylalanine, were studied by gas-phase adsorption on solid amino-acid samples. DL-, D- and L-isomers were investigated for all of the amino acids with the exception of cysteine where only DL- and D- were studied. Langmuir adsorption isotherms show that the strongest interactions are with lysine. Correlation of the relative interaction strength with the chemical structures suggests that binding is strongest to the remote amino groups in the amino-acid side-chain and involves a nucleophilic attack of a lone pair of electrons on the epsilon-nitrogen of lysine to the carbon of the carbonyl group of the methyl benzoate. This suggestion is supported by studies on hydrochlorides of lysine where the side-chain amino groups are protonated and thus cannot participate in a lone-pair interaction. Arginine mono-hydrochloride was found to adsorb more methyl benzoate than even the lysine free-base, an observation which is not fully understood.

Amino Acids↗

PubMed1992

Efficacies of Novel N-Halamine Disinfectants against Salmonella and Pseudomonas Species.

Six novel N-halamine compounds of potential importance as disinfectants to the food-processing industry were tested against Salmonella enteritidis, Salmonella gallinarum, Salmonella typhimurium, and Pseudomonas fluorescens in aqueous solution. Inactivation times for 10-fold reductions were determined as a function of water quality at pH 6.5 and 25 degrees C. Phenol coefficients for the efficacies of the compounds against S. enteritidis have been reported also. When both stability and efficacy data are considered, as well as cost of production, two compounds, 1,3-dichloro-2,2,5,5-tetramethylimidazolidin-4-one and 1-chloro-2,2,5,5-tetramethylimidazolidin-4-one, offer the greatest potential as biocides for the food-processing industry.

Journal Article↗

PubMed1991

Effect of organic N-halamines on selected membrane functions in intact Staphylococcus aureus cells.

Two N-halamine compounds, 3-chloro-4,4-dimethyl-2-oxazolidinone and 1,3-dichloro-4,4,5,5-tetramethyl-2-imidazolidinone, were compared with free chlorine as to their effects on selected membrane functions of intact Staphylococcus aureus cells. Free chlorine was found to cause a loss of permeability control, as measured by the efflux of potassium from the cells and a dramatic increase in hydrogen ion permeability, and to affect cell respiration in a nonreversible fashion, as measured by oxygen uptake. The two N-halamines were found to have very little effect on permeability to either potassium or hydrogen ions but were both found to dramatically inhibit respiration in a reversible manner. It is proposed that the first step in the disinfection process by these N-halamines is an inhibition of respiratory enzymes that, if not reversed, ultimately leads to a loss of cell viability.

Cell Membrane↗

PubMed1990

Potential uses of combined halogen disinfectants in poultry processing.

Five organic N-halamine compounds (combined halogen disinfectants) were compared for their bactericidal activities against Salmonella typhimurium under controlled pH and temperature. All five compounds were effective as bactericides in demand-free buffers ranging from pH 5.0 to 9.0 and treatment temperatures from 4 to 48 C. The range of contact times necessary for a 99.9999% inactivation of viable cells was from .22 to 29 min, depending on the halogen concentration, temperature, and pH of the demand-free buffer. Two of the compounds (3-chloro-4,4-dimethyl-2-oxazolidinone and 1,3-dichloro-4,4,5,5-tetramethyl-2-imidazolidinone) were found to have considerable promise in high-temperature applications, and a third compound (1-bromo-3-chloro-4,4,5,5-tetramethyl-2-imidazolidinone) was more suitable for low-temperature treatments.

Animals↗

PubMed1990

Combined halogen disinfectants in poultry processing.

Three organic N-halamine compounds (combined halogen disinfectants) were compared with free chlorine (as calcium hypochlorite) as bactericides against Salmonella typhimurium and unidentified normal poultry bacterial flora under controlled conditions of pH, temperature, and halogen demand similar to those encountered in poultry processing. Two of the compounds (3-chloro-4,4-dimethyl-2-oxazolidinone and 1,3-dichloro-4,4,5,5-tetramethyl-2-imidazolidinone) at a concentration of 50 mg/L were found to cause a 99.9999% decline in viable organisms in less than 1 min at 48 C, whereas a third compound (1-bromo-3-chloro-4,4,5,5-tetramethyl-2-imidazolidinone) was found to be less suitable (5.6 min to 99.9999% decline under the same conditions).

Animals↗

PubMed1988

Inactivation of Giardia lamblia and Giardia canis cysts by combined and free chlorine.

Free chlorine and a combined organic N-chloramine (3-chloro-4,4-dimethyl-2-oxazolidinone, compound 1) were compared for efficacy as disinfectants against an admixture of cysts of Giardia lamblia and Giardia canis in water solution under a variety of test conditions; variables were pH, temperature, and water quality. In general, compound 1 was found to reduce the giardial excystation in the solutions at lower concentration or shorter contact time at a given total chlorine concentration than did free chlorine.

Analysis of Variance↗

PubMed1988

Is free halogen necessary for disinfection?

The principle of Le Chatelier was used in demonstrating that 3-chloro-4,4-dimethyl-2-oxazolidinone (compound 1) itself kills Staphylococcus aureus rather than the very small amount of free chlorine in hydrolysis equilibrium with compound 1. On the other hand, when the N-bromo analog of compound 1 (compound 1B) was used as the disinfectant, the mixture of combined compound 1B and free bromine formed in the hydrolysis equilibrium provided disinfection. When the hydrolysis equilibrium for 1B was suppressed to the level at which a negligible amount of free bromine remained in solution, combined compound 1B was much more efficacious than combined compound 1 at killing S. aureus.

Bromine↗

PubMed1987

Syntheses and antibacterial activity of new N-halamine compounds.

The syntheses of three new N,N'-dihalamine compounds in the class of tetramethylimidazolidinones are described. The stabilities and disinfection efficacies against Staphylococcus aureus of the compounds in water solution are compared with those for 3-chloro-4,4-dimethyl-2-oxazolidinone which has been studied extensively in recent years in these laboratories and elsewhere. The new compounds exhibit considerable promise as general-purpose disinfectants, particularly in applications for which long-term stability is necessary.

Disinfectants↗

PubMed1987

Bactericidal properties of an organic N-chloramine formed in situ.

Agent I (3-chloro-4,4-dimethyl-2-oxazolidinone) formed in situ was compared with pre-formed agent I as a disinfectant against Staphylococcus aureus. In situ formation involved combining the non-chlorinated oxazolidinone precursor with calcium hypochlorite to form 5 and 10 mg/l total chlorine concentrations of agent I. The variables included in the study were temperature, pH and concentration. Overall the bacteria were killed more rapidly at 22 degrees than at 4 degrees C. The in situ formation appeared to occur most rapidly at pH 7.0, slightly slower at pH 9.5, and very slowly at pH 4.5 as evidenced by the presence of residual free chlorine. In the in situ experimental runs the 5 and 10 mg/l concentrations were equally effective in obtaining a six log decline in cfu/ml. This study indicates the potential for using the organic N-chloramine as a general purpose disinfectant while omitting the laboratory synthesis of the final product.

Chemical Phenomena↗

PubMed1987

Inactivation of Legionella pneumophila by hypochlorite and an organic chloramine.

The susceptibility of a strain of Legionella pneumophila to disinfection by an organic halamine, free chlorine, and a mixture of the organic halamine and free chlorine was assessed. The organic halamine was found to have superior stability in solution and to exhibit adequate disinfectant potential over a period of 1 month of repeated reinoculations of fresh bacteria. The combined halamine exhibited great potential for use in maintaining closed-cycle cooling water systems free of L. pneumophila.

Calcium↗

PubMed1987

Bactericidal activities of selected organic N-halamines.

The bactericidal efficacies of three organic N,N'-dihalamine disinfectants in the class of compounds termed imidazolidinones were determined for combinations of pH, temperature, and water quality treatments by using Staphylococcus aureus and Shigella boydii as test organisms. The compound 1,3-dibromo-4,4,5,5-tetramethyl-2-imidazolidinone was found to be the most rapidly acting bactericide, especially under halogen-demand-free conditions. The mixed N,N'-dihalamine 1-bromo-3-chloro-4,4,5,5-tetramethyl-2-imidazolidinone was found to be intermediate in terms of rate of disinfection, while the compound 1,3-dichloro-4,4,5,5-tetramethyl-2-imidazolidinone was observed to be the slowest acting bactericide. When overall effectiveness was judged on the basis of stability of the disinfectants along with rates of disinfection, the mixed halamine was considered to exhibit great potential for use as a disinfectant in an aqueous solution.

Chemical Phenomena↗