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Role of Surfactant in Other Organs
Published in Jacques R. Bourbon, Pulmonary Surfactant: Biochemical, Functional, Regulatory, and Clinical Concepts, 2019
Adsorption is a particularly common process, especially of the weak physical type where van der Waals’ forces may hold layers several hundred molecules in thickness in loose association with the surface. Much stronger adsorption can be effected when one of the chemical groups (moieties) in the molecule forms a chemical bond with the surface known as chemisorption.1,2 This is still not obvious to an observer unless the two ends of the adsorbed molecule are of widely differing character, especially in their affinity for water, as one finds between the polar and nonpolar moieties of surfactant molecules. The attachment of a surfactant molecule by, for instance, electrostatic attraction between the polar moiety and a fixed charge on the surface orientates the molecule with its nonpolar group facing outward. This effects a total “change of personality” in which a highly wettable surface such as glass or cotton can be rendered hydrophobic and water repellent. Thus, droplets of water which would have spread spontaneously on clean glass now “bead up” to display a contact angle which provides a convenient index of the change in surface energy upon adsorption.3
Chemical, Biochemical, and Medicinal Properties of the Diphosphonates
Published in Richard L. Hilderbrand, The Role of Phosphonates in Living Systems, 2018
Marion D. Francis, Raymond R. Martodam
The chemisorption of the diphosphonates to calcium phosphate nuclei during their formation leads to a physical chemical inhibition of crystal growth of apatite. This effect produces an apparent increase in solubility of hydroxyapatite and can block apatite deposition as in calculus formation (see Section III.C). The possible role of chemisorption as it relates to biological mineralization of mammalian hard tissue is discussed below.
Polymer–Silver Nanocomposites: Preparation, Characterisation and Antibacterial Mechanism
Published in Huiliang Cao, Silver Nanoparticles for Antibacterial Devices, 2017
After the preparation of Ag NPs, the nanoparticles can be modified via ligand exchange reactions wherein the capping molecules of the obtained nanoparticle surface are instead of a polymer, or via chemical alteration of the capping molecule. Sodium citrate and various cationic surfactants, such as cetyltrimethylammonium bromide (Jana et al. 2001), benzyldimethyl hexadecylammonium chloride (Nikoobakht and El-Sayed 2003; Park et al. 2010) and cetylpyridinium chloride monohydrate (Bronstein et al. 2000; Setua et al. 2010), are commonly used as capping molecules. However, these capping molecules are labile with weakly chemisorption to the nanoparticle surface. As a result, ligand exchange reactions become a general strategy for surface modification of nanoparticles with polymer grafts (Figure 5.2). The capping molecules are substituted through covalent binding of the graft to the nanoparticle surface or physisorption of the polymer graft. The effectiveness of this displacement depends on the affinity of the polymer graft with the nanoparticle surface. Therefore, postsynthetic modification of Ag NPs is a typical method for polymer grafts that display strong binding affinity to the nanoparticle surface. For example, thiol-functionalised polymer grafts are widely used in the surface modification of plasmonic nanoparticles, because the high affinity of the thiol to Ag makes the terminus of the polymer easily graft to the Ag NPs surface (Love et al. 2006; Rucareanu et al. 2008).
A γ-cyclodextrin-based metal–organic framework (γ-CD-MOF): a review of recent advances for drug delivery application
Published in Journal of Drug Targeting, 2022
Asma Hamedi, Anastasia Anceschi, Alessia Patrucco, Mahdi Hasanzadeh
Since CD-MOF-1 is susceptible to an aqueous environment, the improvement of the water-stability of CD-MOF-1 for loading drug molecules is gaining attention. Liu et al. [39] synthesised CD-MOFs with microwave irradiation and PEG 20000 was used as the size modulator. The control of size and morphology were obtained and optimised controlling the reaction time, temperature, and solvent ratio during the synthesis process. Fenbufen was selected to investigate the drug loading behaviour in micro and nano-MOF. Rapid adsorption over the first h was exhibited with a loading of 196 mg/g. After 2 h the equilibrium was reached. The adsorption kinetics were fitted with a pseudo-second-order kinetic model suggesting that the drug adsorption is mainly associated with chemisorption behaviour.
Surgical applications of intracorporal tissue adhesive agents: current evidence and future development
Published in Expert Review of Medical Devices, 2020
Nicholas Gillman, David Lloyd, Randy Bindra, Rui Ruan, Minghao Zheng
In the context of adhesion, molecular bonding is divided into chemisorption and physisorption. Chemisorption refers to interactions between adhesive compounds and a biological surface that results in primary bond formation such as covalent and ionic bonds. Common interactions including amide [16,17] and Schiff base formation [18]. Physisorption refers to interactions between molecules and compounds resulting in secondary bond formation, with common interactions including π-π stacking, hydrogen bonding, dipole–dipole interactions and Van der Waals instantaneous dipoles. These forces create weak interactions at the tissue surface which can reinforce adhesive and cohesive strength [19]. In terms of cohesive strength, the density of crosslinking plays a predominant role [20]. Common interactions include amide linkages and covalent imine bond formation between carbonyl and amide functional groups (Schiff base formation) [18,21].
Arabian Primrose leaf extract mediated synthesis of silver nanoparticles: their industrial and biomedical applications
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2020
Shruti Nindawat, Veena Agrawal
From the results obtained, it is clear that the rate of Ah-AgNPs catalysed reaction is very fast. This might be due to the smaller size, spherical shape and crystal structure of nanoparticles which are chemically active and prone to dissolve easily producing catalytically active sites. This results in the availability of large number of binding sites for the chemisorption of reactants thereby enhancing the reaction rate [40].