Natural steroid-based cationic copolymers cholesterol/diosgenin-r-PDMAEMAs and their pDNA nanoplexes: impact of steroid structures and hydrophobic/hydrophilic ratios on pDNA delivery

Using natural-based lipids to construct biocompatible, controllable and efficient nanocarriers and elucidating their structure–function relationships, was regarded as an important area for creating sustainable biomaterials.

Structural Polymorphism of Single pDNA Condensates Elicited by Cationic Block Polyelectrolytes

DNA folding is a core phenomenon in genome packaging within a nucleus. Such a phenomenon is induced by polyelectrolyte complexation between anionic DNA and cationic proteins of histones. In this regard, complexes formed between DNA and cationic polyelectrolytes have been investigated as models to gain insight into genome packaging. Upon complexation, DNA undergoes folding to reduce its occupied volume, which often results in multi-complex associated aggregates. However, when cationic copolymers comprising a polycation block and a neutral hydrophilic polymer block are used instead, DNA undergoes folding as a single molecule within a spontaneously formed polyplex micelle (PM), thereby allowing the observation of the higher-order structures that DNA forms. The DNA complex forms polymorphic structures, including globular, rod-shaped, and ring-shaped (toroidal) structures. This review focuses on the polymorphism of DNA, particularly, to elucidate when, how, and why DNA organizes into these structures with cationic copolymers. The interactions between DNA and the copolymers, and the specific nature of DNA in rigidity; i.e., rigid but foldable, play significant roles in the observed polymorphism. Moreover, PMs serve as potential gene vectors for systemic application. The significance of the controlled DNA folding for such an application is addressed briefly in the last part.

INFLUENCE OF FLOCCULANT TYPE ON STRENGTH CHARACTERISTICS OF FLOCS IN CLAY-SALT SUSPENSIONS

The results of studies on the effect of the flocculant type on the strength characteristics of floccules in clay-salt suspensions, obtained using a laser analyzer of particle size Lasentec D600L FBRM systems were presented in the article. The coefficients of strength and reduction of aggregates formed by polyacrylamide and its anionic and cationic copolymers were determined. Increasing the speed of mixing by using of polymers various types leads to the destruction of the formed aggregates in the flocculated suspension. The size of flocs induced by a cationic flocculant is reduced from 250 to 110 mm, for anionic and non-ionic flocculants - from 500 to 250 mm. The dependence of floc strength on the macromolecules adsorption mechanism on a solid surface was established. The decrease in hydrodynamic effects entails the partial restoration of floccules. It was shown that the recovery of flocs for all studied polymers was limited, which indicates a significant irreversibility of the aggregates destruction process. When using cationic flocculant, the ability to restore the aggregates is 2.5 times lower compared to anionic and non-ionic polymers. For nonionic and anionic polymers, the dependence of flocs coefficients of strength and recovery on the flocculant dosage was established. Dosage of cationic polymer does not affect these indicators. The dynamics of flocculation, destruction and reflocculation processes using various flocculants was considered. The influence of the charge type and polymer consumption on the mechanism of particles interaction was established. The potential possibility of using the obtained results to improve the technology of potassium chloride production at the stages of thickening and dehydrating clay-salt sludge was shown.

Antibacterial properties of synthesized cyclic and linear cationic copolymers

Antibacterial activities of cationic cyclic copolymers compared to those of their linear counterparts were investigated.

Influence of Polymer Composition and Substrate on the Performance of Bioinspired Coatings with Antibacterial Activity

A series of methacrylic copolymers bearing thiazolium cationic groups and catechol moieties were evaluated as antibacterial coatings on a variety of materials including aluminum and plastics such as polycarbonate, poly(methyl methacrylate), and silicone rubber. The thermal properties of the copolymers were first studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The cationic copolymers were thermally stable up to 200 °C and presented glass transition temperatures values well above 100 °C; thus, an acceptable thermal behavior for typical biomedical applications. The cationic copolymers with variable content of the adhesive anchoring N-(3,4-dihydroxyphenethyl) methacrylamide (DOMA) units were coated onto the metal and polymeric substrates by drop casting and the adhesive properties of the obtained coatings were further evaluated as a function of DOMA content and substrate. Optical profilometry, attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectra, and antimicrobial studies reveal that the coatings adhere stronger to metal substrates than to the polymeric substrates. The copolymers with higher content of DOMA, 24 mol.%, resist solvent erosion treatment when coated onto all substrates and exhibit antimicrobial activity against Gram-positive S. aureus bacteria after this erosion treatment. In contrast, copolymers with low content, 9 mol.% of DOMA, only remain attached onto the aluminum metal substrate after solvent treatment, while on polymeric substrates the coatings are almost removed and do not show any efficacy against S. aureus bacteria.

Stabilization of Silver Nanoparticles by Cationic Aminoethyl Methacrylate Copolymers in Aqueous Media—Effects of Component Ratios and Molar Masses of Copolymers

The ability of aminoethyl methacrylate cationic copolymers to stabilize silver nanoparticles in water was investigated. Sodium borohydride (NaBH4) was employed as a reducing agent for the preparation of silver nanoparticles. The objects were studied by ultraviolet-visible (UV-vis) spectroscopy, dynamic light scattering (DLS), analytical ultracentrifugation (AUC) and scanning electron microscopy (SEM). Formation of nanoparticles in different conditions was investigated by varying ratios between components (silver salt, reducing agent and polymer) and molar masses of copolymers. As a result, we were successful in obtaining nanoparticles with a relatively narrow size distribution that were stable for more than six months. Consistent information on nanoparticle size was obtained. The holding capacity of the copolymer was studied.