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Nowadays, the search for and development of new forms of materials with biocides is an actual problem of the modern science of nanosized materials due to the problem of microbiological contamination, which can be solved by using nanocontainers carrying biocides. Depending on the morphology of the nanocontainers and the filled active agents, it is possible to create coatings with specially designed self-healing functionality or multifunctional properties. The purpose of this work was to produce submicro-containers (SMCs) with a shell of SiO2 nanoparticles and a core of polymerized 3- (trimethoxysilyl) propyl methacrylate filled with 5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) in an oil in water (O/W) emulsion. The chemical nature of the individual components of the system and nano-capsules were investigated using NMR spectroscopy. The size and zeta potential of the SMCs were measured by a dynamic light scattering method (d = 170&ndash, 180 nm, polydispersity index PDI = 0.125 and zeta-potential = 55 mV), the morphology of their outer surface was determined using SEM. The results of NMR analysis showed that during the addition of the biocide into the SMCs, its chemical structure is retained, as is its activity. Minor changes in the chemical shifts of the 1H NMR spectra of the SMCs with DCOIT, as well as of the biocide itself, confirm the inclusion of DCOIT inside the SMCs.

This paper is devoted to the investigation of N-isopropylacrylamide-based microgels as potential drug delivery systems and other pharmaceutical applications. Surfactant free emulsion polymerization (SFEP) and emulsion polymerization techniques were employed to copolymerize PNIPAM with acrylic acid (AA), with 3-acrylamidophenylboronic acid (3-APB) and (3-acrylamidopropyl)trimethylammonium bromide (ATMA), and with 1-vinylimidazole (VI). The resultant microgel particles exhibited multi-responsive behaviour being sensitive to changes in temperature, pH. The PNIPAM-co-3-APB-ATMA microgels were sensitive to concentration of glucose, whilst the PNIPAM-co-VI microgels were sensitive to certain metals, copper in particular. The microgel containing AA exhibited characteristic temperature-sensitive behaviour with volume a phase transition temperature (VPTT) in the range of 35°–40 °C and showed pH-sensitive features as the particles collapsed at low and swelled at high pH values. The microgels containing various concentration of VI were also examined on sensitivity to temperature and pH changes. The investigation of such microgels with increasing temperature showed similar behaviour to those containing AA as the microgel particles shrunk continuously and the LCST has been shifted to higher temperatures (in the range of 35°–45 °C). The particle size of these microgels was also investigated as a function of pH; the microgel particles swelled at low and collapsed at high pHs. The particle size of the PNIPAM-co-3-APB-ATMA microgels was investigated both as a function of temperature and glucose concentration. The microgels showed typical behaviour of PNIPAM microgels copolymerized with functional monomer (3-APB and ATMA) by continuous shrinking with increasing temperature and shifted LCST towards higher temperatures. Additionally, these microgels showed swelling behaviour with the increase of glucose concentration at physiological conditions, i.e. particles swelled in the range of glucose concentration between 0.1 and 10 mmol/L at 35 °C and pH 7.5. The behaviour of these microgels was also investigated at 35 °C and pH 8.5 as a function of glucose concentration. Although the swelling of the particles was slightly larger at pH 8.5, considerable swelling was also observed at pH 7.5 making them the first microgel system to be glucose sensitive at physiological pH and temperature. Swelling of the particles at the pH level of human blood (in range of 7.35–7.45) as well as having lower critical solution temperature in the range of temperature of the human body gives an opportunity to develop these microgel particles further as potential drug-delivery agents.

The synthesis and properties of submicrocontainers with a shell of nanoparticles of silicon dioxide and a core of polymerized 3-(Trimethoxysilyl) propyl methacrylate loaded with 5Dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) are considered. The resulting containers were characterized by scanning electron microscopy SEM, laser correlation spectroscopy and thermogravimetric analysis. The obtained submicrocontainers show low polydispersity with a small increase in size in comparison with the initial droplet size of the Pickering emulsion. The Zeta potential of the final containers was sufficiently negative at pH7 to be stable. The maximum release of encapsulated biocide was observed over approximately 24–27 h with a lease of about 78% of the encapsulated biocide during 3.5 h. The effectiveness of the encapsulated biocide by the Pickering emulsion technique was studied by tests on the growth rate of a microfungi colony (Aspergillus niger, Aspergillus awamori) and the growth rate of the bacteria Bacillus cereus. The test shows that the submicrocontainers of DCOIT facilitate a growth inhibition of 70% against 52% for the free biocide after 5 days, this is due to the fact that free biocide loses its activity promptly, while the encapsulated biocide is released gradually, and thus retains its effectivity for a longer time.

Polymer/surfactant mixtures have a wide range of industrial and technological applications, one of them being the use in microencapsulation and emulsion stabilization processes. These mixtures are able to form adsorption layers at the surface of oil droplets and so affect the emulsion stability, which depends on the polyelectrolyte/surfactant nature, concentrations ratio, method of the emulsification, etc. Polyelectrolytes alone show low surface activity in contrast to surfactants, which adsorb at the water/oil interface, making the droplets charged, but they are insufficient to stabilize emulsions. When an oppositely-charged polymer is added to the surfactant solution, a steric barrier is formed, which prevents coalescence and enhances the stability. The present review is devoted to the recent studies of the use of polymer/surfactant mixtures for the encapsulation of active ingredients and stabilization of single and double emulsions. Active ingredients are added to the oil phase prior to emulsification so that any subsequent dissolution of the core, like in other encapsulation protocols, can be omitted. By measuring the interfacial tension and dilational rheology it is possible to find optimum conditions for the emulsion formation and hence for encapsulation. Therefore, such systems have become a prominent approach for the encapsulation of active ingredients.