Tuning the Properties of Silver Monolayers for Biological Applications
Huiliang Cao in Silver Nanoparticles for Antibacterial Devices, 2017
For biological applications, silver nanoparticle coatings immobilised on monolayers of cationic polyelectrolytes seem to be the most promising. Polyelectrolytes are charged molecules consisting of ionisable groups, which release counterions when desolating in polar solvents such as water (Morga and Adamczyk 2013). Because of the growing applications of polyelectrolytes, especially in medicine, many techniques have been exploited to manufacture monolayer and multilayer films of desired coverage and structure. Thin polyelectrolyte films have been fabricated using various techniques such as Langmuir–Blodgett or self-assembly. One of the most promising approaches of surface modification using polyelectrolytes is the LBL assembly technique, which has become a powerful tool for fabricating thin materials with precise control of film composition and structure (Morga and Adamczyk 2013). It is worth mentioning that most cationic polyelectrolytes are building blocks used for the preparations of microcapsules applied in drug delivery systems (Antipov and Sukhorukov 2004).
Elements of Polymer Science
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
A classification of polymers especially useful in the case of water-soluble polymers is based on the electric charge born by the macromolecule. Electrically neutral water-soluble polymers include various polysaccharides, mostly cellulose ethers, polyacrylamides, and certain polyethers, such as poly(ethylene glycols). Polyelectrolytes are water-soluble polymers with many electrically charged groups per molecule. They form polyions on dissociation. These polyions may be polyanions with negative charges as in dissociated poly(acrylic acid) - or polycations as in protonated poly(vinylamine), . They may also be polysalts, as in the sodium salt of poly(acrylic acid), . Polyions should be distinguished from macroions, which carry only one ionic group, usually at one chain end. Water-insoluble polymers with relatively few ionic groups in the chain are known as ionomers. PREPARATIONS OF MACROMOLECULAR COMPOUNDS
Nanoparticle Synthesis and Administration Routes for Antiviral Uses
Devarajan Thangadurai, Saher Islam, Charles Oluwaseun Adetunji in Viral and Antiviral Nanomaterials, 2022
The production of micelles is based on the critical micellar concentration (CMC), which should be reached by phospholipids and polymers in water media to the formation of the hydrophobic core and the hydrophilic shell (Manaia et al. 2017). To produce nanofilms, the Layer-by-Layer (LbL) methodology stands out, created by Decher (1997). Basically, this methodology consists of immersing a substrate in cationic and anionic solutions, which causes an electrostatic self-assembly. For this purpose, polyelectrolytes, polymers that contain ionic groups in their repetitive units, are used. These ionic groups in aqueous solution are partially ionized, and thus, different charge densities in the polymer are obtained (Decher et al. 1992a,b, 1994; Faria-Tischer and Tischer 2012; Medeiros et al. 2013).
The development of stimuli-responsive polymeric micelles for effective delivery of chemotherapeutic agents
Published in Journal of Drug Targeting, 2018
Yimu Li, Aihua Yu, Lingbing Li, Guangxi Zhai
Polyelectrolytes are a typical category of pH-responsive polymers with large amount of ionic functional groups, such as carboxyl groups and amide groups. The ionisation degree of these functional groups will change as the variation of environmental pH and consequently, phase transformation of polyelectrolytes will be triggered, which greatly influence the solubility of polyelectrolytes. When micelles consisted of polyelectrolytes are transported from slightly alkaline normal tissues to acidic tumour tissues, this kind of pH-responsive solubility change of polyelectrolytes may lead to structure collapsing of micelles and cargo release from the core of the micelles. Recently, many kinds of pH-responsive polyelectrolyte based polymeric micelles have been developed through the electrostatic interactions among multiple kinds of polyelectrolytes or between polylectrolytes and drugs [11–16,53].
Recent advances in polymeric materials for the delivery of RNA therapeutics
Published in Expert Opinion on Drug Delivery, 2019
David Ulkoski, Annette Bak, John T. Wilson, Venkata R. Krishnamurthy
All polymers that bear cationic and/or anionic charges under physiological conditions can be considered polyelectrolytes. In contrast, zwitterionic polymers such as polyampholytes consist of both cationic and anionic groups along the main or side chain. Charge stoichiometry of polyions can be balanced the produce neutral, cationic, or anionic character. The interactions between acidic and basic groups establish zwitterionic properties that minimize the net charge to mitigate charge-related toxicities that exist with purely cationic polyelectrolytes [237]. These polymers are typically responsive to multiple stimuli, converting between anti-polyelectrolyte or polyelectrolyte characteristics within different environmental conditions. When the zwitterionic linkages are subjected to intracellular pH, bond dissociation and net charge increase can occur, allowing for endosomal escape and payload release [238–240].
Surface-modified polymeric nanoparticles for drug delivery to cancer cells
Published in Expert Opinion on Drug Delivery, 2021
Arsalan Ahmed, Shumaila Sarwar, Yong Hu, Muhammad Usman Munir, Muhammad Farrukh Nisar, Fakhera Ikram, Anila Asif, Saeed Ur Rahman, Aqif Anwar Chaudhry, Ihtasham Ur Rehman
When two oppositely charged polyelectrolytes are mixed, they construct a complex structure of polyelectrolyte nanoparticles. The stability of these nanoparticles is dependent on the charge density and stiffness of polyelectrolyte chains [132]. Different single and multi-layered nanoparticles have fabricated by electrostatic interaction of polyelectrolytes. This method is termed as a layer-by-layer deposition. In this procedure, excess polyelectrolyte solution with opposite charges was added to a colloidal dispersion to form coated nanoparticles (Figure 4d). It shows the reversal of surface charges in coated nanoparticles. The coated nanoparticles were then centrifuged and washed. Further, a second polyelectrolyte solution with opposite charges was added to coated nanoparticles and obtained double-layered electrolyte nanoparticles. Again, charge reversibility was observed in these nanoparticles. Similarly, multi-layered nanoparticles can be formulated by repeating this process [133]. Benefits of layer-by-layer deposition include good control on the thickness of polymer coatings by altering the number of layers and solution conditions, formulation of multicomponent polyelectrolyte nanoparticles from a variety of polymers, and fabrication of nanoparticles with distinguished morphologies and tailored composition [134]. We prepared chitosan–poly(acrylic acid) (CS–PAA) polyelectrolyte nanoparticles via electrostatic interaction between negatively charged PAA and positively charged CS groups [135,136].