China
Africa
Explore chapters and articles related to this topic
Cationic Surfactants and Quaternary Derivatives for Hair and Skin Care
Published in Randy Schueller, Perry Romanowski, Conditioning Agents for Hair and Skin, 2020
Matthew F. Jurczyk, David T. Floyd, Burghard H. Grüning
By general definition, quaternary ammonium salts are "a type of organic compound in which the molecular structure includes a central nitrogen atom joined to four organic groups as well as an acid radical" (1). At least one of these substitution groups is typically hydrophobic in nature. Quaternaiy derivatives based on fatty acids, proteins, sugars, and silicone polymers are all used in the cosmetic industry. Quaternary ammonium salts are cationic surface-active compounds and adsorb readily onto surfaces such as hair and skin.
Organic Chemicals
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
Detergents are substances that allow the penetration of water into lipid areas that are non-water-soluble. Hydrocarbons such as petrol and mineral oils are completely insoluble in water while acids such as acetic or sulfuric acids are miscible with water. This solubility is connected with the fact that both are polar compounds. Decomposition of fats and oils occurs naturally by means of alkalis, yielding the alkali metal salts of fatty acids, the soaps, or artificially by synthetic aliphatic hydrocarbons attaching to acids. The attaching of acids makes them polar and more hydrophilic. There are anionic, cationic, and nonionic substances. The anions, especially the natural ones, are the least toxic and often tolerated by most of the chemically sensitive. Natural soaps are sodium salts of stearic and palmitic acid while soft soaps consist of potassium salts of these acids. The most important synthetic anionic soaps include sodium alkylbenzene sulfonate, sodium alkyl sulfonate, and sodium alkyl sulfate. These, in themselves, may cause less environmental damage with degradation occurring in 10 days versus other synthetic detergents.399 However, these synthetics may be troublesome to the chemically sensitive individual. Cationic detergents (positively charged), for example, quaternary ammonium salts, are poisonous to microorganisms and can be used for disinfection. These substances are generally not very harmful to humans, but we have seen some chemically sensitive individuals react to them. At the EHC-Dallas, we use benzalkoniums as disinfectants because of their lesser reactivity in the chemically sensitive.
Liposomes
Published in Danilo D. Lasic, LIPOSOMES in GENE DELIVERY, 2019
The majority of positive charges of cationic lipids are based on (poly)amines and quaternary ammonium salts. Not many specific details are known about the pK values of these cationic lipids and counterion associations with the bilayers. Amines are weak bases and upon interaction with acids yield aminium salts. When the central nitrogen atom is charged but is not attached to a hydrogen atom, the compound is called a quaternary ammonium salt. Quaternary ammonium salts and guanidine based compounds are very strong bases and pKa values are above 12. Tertiary amines (RR′R″N, where R is an alkyl group) are less basic than secondary (RR′NH) and primary (RNH2) amines. For simple alkyl amines pKa values are typically above 10 for primary and secondary amines and above 9 for tertiary. Arylamines are weaker bases and aromatic amines are very weak bases. The presence of double bonds and nearby charges, however, can reduce the pKa values and in dense networks, such as in dendrimers the pKa values may be below 6. Amides (one R is oxygen) are very weak bases. In addition to unknowns about the pK values of various polyamines conjugated to hydrophobic parts also the surface pH is not well defined. Positively charged surface attracts hydroxyl ions and surface pH increases. If one performs simple electrostatic evaluation this increase can be up to 3 pH units in low salt conditions. However, this crowding of hydroxyls also drastically reduces their activity which may compensate for the increased concentration and the real surface pH has not been yet precisely determined.
Tailoring the monomers to overcome the shortcomings of current dental resin composites – review
Published in Biomaterial Investigations in Dentistry, 2023
Jingwei He, Lippo Lassila, Sufyan Garoushi, Pekka Vallittu
Although the quaternary ammonium group has strong and broad-spectrum antibacterial activity, its hydrophilic structure can increase the water sorption of DRCs and influence the water resistance of DRCs. Moreover, the antibacterial activity of quaternary ammonium methacrylate-containing DRCs can be reduced due to the electrostatic interactions between quaternary ammonium salts and proteins in saliva [125,126]. Therefore, other bactericidal structures, such as heterocyclic rings [127–129] and natural bactericidal structures [130–135], were chosen to be connected with the (meth)acrylate group and then applied in dentistry as immobilizable bactericides (as shown in Figure 15). All these monomers endowed DRCs with antibacterial activity without sacrificing physicochemical properties [127–135], thus showing great potential for clinical applications.
Bioprospecting of aqueous phase from pyrolysis of plant waste residues to disrupt MRSA biofilms
Published in Biofouling, 2023
Srividhya Krishnan, Subramaniyasharma Sivaraman, Sowndarya Jothipandiyan, Ponnusami Venkatachalam, Saravanan Ramiah Shanmugam, Nithyanand Paramasivam
Moreover, S. aureus has acquired drug resistance against a wide class of antibiotics, and Methicillin Resistant Staphylococcus aureus (MRSA) are wide spread (Kouyos et al. 2013). Currently, vancomycin, telavancin, ceftaroline, daptomycin are some of the commonly prescribed classes of antibiotics used for the treatment of bacterial infections by binding to the penicillin binding protein sites (Verma et al. 2021). It was reported that almost 40% of the S. aureus isolates from hospital environments were recently identified as MRSA (Shiadeh et al. 2022). In the U.S., the Centre for Disease Control and Prevention (CDC) has estimated that close to 80,000 infections and 11,000 deaths are caused by MRSA every year (Grigg et al. 2018). More than 100,000 deaths were reported in 2019 due to MRSA infections (Shiadeh et al. 2022). Several possible mechanisms on the acquirement of antibiotic resistance by MRSA have been proposed in the literature. One such mechanism involves the modification in the penicillin binding protein sites (PBP2a) present in the cell membrane of the bacteria thereby preventing antibiotic binding (Yuan et al. 2011). There are several small molecule inhibitors that have been developed to treat the MRSA infection, among which, quaternary ammonium salts with oxadiazoles moiety were found to be effective against MRSA variants. Quaternary ammonium salts damage the membrane potential and affects the cytoplasmic components (Verma et al. 2021).
Antimicrobial and antifouling polymeric coating mitigates persistence of Pseudomonas aeruginosa biofilm
Published in Biofouling, 2019
Brenda G. Werner, Julia Y. Wu, Julie M. Goddard
Much of the research in antimicrobial coatings focus on embedding small molecule antimicrobials in a polymer matrix (Nablo et al. 2005; Banerjee et al. 2011; Bastarrachea et al. 2015). While effective, the necessary leaching of the antimicrobial agent for efficacy means that (in addition to significant concerns about environmental toxicity and development of resistant organisms) coatings will lose efficacy after repeated use. There would therefore be significant benefit to an antimicrobial coating in which the antimicrobial agent is bound as part of the polymer structure, therefore unlikely to leach, and has broad spectrum efficacy against foodborne pathogens. The authors’ group and others have demonstrated the potential of N-halamine based polymers in controlling microbial growth, but their reliance on halogenation to be effective renders them ineffective under conditions of high organic load (Hui and Debiemme-Chouvy 2013; Bastarrachea et al. 2014; Demir et al. 2015; Cerkez et al. 2016; Cossu et al. 2017). Quaternary ammonium salts (QAS) can be incorporated into a polymer coating with retained antimicrobial activity, but the charged nature of QAS may actually promote fouling. Recent work (Majumdar et al. 2008; Liu et al. 2013; Bastarrachea and Goddard 2015, 2016) has shown that polymer chemistry can be tailored so that these cationic amine-containing polymer coatings have no net charge and subsequently exhibit both antimicrobial and non-fouling properties.