Liposomes
Danilo D. Lasic in 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.
Cationic Surfactants and Quaternary Derivatives for Hair and Skin Care
Randy Schueller, Perry Romanowski in Conditioning Agents for Hair and Skin, 2020
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.
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.
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).
Alkyl rhamnosides, a series of amphiphilic materials exerting broad-spectrum anti-biofilm activity against pathogenic bacteria via multiple mechanisms
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2018
Guanghua Peng, Xucheng Hou, Wenxi Zhang, Maoyuan Song, Mengya Yin, Jiaxing Wang, Jiajia Li, Yajie Liu, Yuanyuan Zhang, Wenkai Zhou, Xinru Li, Guiling Li
The synthesis of N-dodecyl rhamnose amine quaternary ammonium salt was divided into two steps. In the first step, white needle crystals (pure N-dodecyl rhamnose amine) were obtained after recrystallization in 80.2% yield. The second step is quaternization reaction. In order to accelerate the quaternization reaction, a large excess of methyl iodide was added into the mixture, n (rhamnose amine):n (methyl iodide) = 1:4. Due to the relatively low boiling point of methyl iodide, the excess of methyl iodide could be distilled off with the solvent after the reaction. The yield of the second step was 94.5%. So, the overall yield of N-dodecyl rhamnose amine quaternary ammonium salt, which was a sticky brown syrup-like substance, was 75.8%. The chemical formula of the 12N+-Rha was confirmed by the molecular ion peak in mass spectra (m/z 360.44 [M–I]+, as calculated m/z for C20H42N+O4 is 360.55[M–I]+) (Figure 3).
Related Knowledge Centers
- Ammonium
- Detergent
- Organic Chemistry
- Ph
- Polymer
- Organyl Group
- Ion
- Salt
- Polyquaternium
- Antimicrobial