A. G. Skirtach

Polyelectrolyte microcapsules for biomedical applications

In this paper we review the recent contributions of polyelectrolyte microcapsules in the biomedical field, comprising in vitro and in vivodrug delivery as well as their applications as biosensors.

On the mechanical stability of polymeric microcontainers functionalized with nanoparticles

We present key factors that influence the mechanical stability of polyelectrolyte/nanoparticle composite microcontainers and their encapsulation behavior by thermal shrinkage. Poly(diallyldimethylammonium chloride) (PDADMAC), poly(styrenesulfonate) (PSS) microshells and citrate-stabilized gold nanoparticles are used. The presence of nanoparticles in the microshell renders the encapsulation process by heat-shrinking more difficult. The encapsulation efficiency is found to decrease as the concentration of material to be encapsulated increases. Increasing nanoparticle content in the microshell or the concentration of dextran increases the likelihood of getting fused and damaged capsules during encapsulation. On the other hand, mechanical studies show that doping microshells with gold nanoparticles significantly increases their stiffness and resistance to deformation. Internalization of capsules by cells supports that the incorporation of metal nanoparticles makes the shells more resistant to deformation. This work provides information of significant interest for the potential biomedical applications of polymeric microshells such as intracellular storage and delivery.

Mucosal irritation potential of polyelectrolyte multilayer capsules

Polyelectrolyte multilayer capsules have recently gained interest as carriers for drug delivery. When envisioning mucosal administration, one is focused with potential concerns such as tissue irritation and tissue damage, induced by the carrier itself. In this paper we demonstrate the use of a slug-based (Arion lusitanicus) assay to evaluate the mucosal irritation potential of different types of polyelectrolytes, their complexes and multilayer capsules. This assay allows to assess in a simple yet efficient way mucosal tissue irritation without using large numbers of vertebrates such as mice, rabbits or non-human primates. We found that although single polyelectrolyte components do induce tissue irritation, this response is dramatically reduced upon complexation with an oppositely charged polyelectrolyte, rendering fairly inert polyelectrolyte complexes. These findings put polyelectrolyte multilayer capsules further en route towards drug delivery applications.

Preparation of polyelectrolyte microcapsules with silver and gold nanoparticles in a shell and the remote destruction of microcapsules under laser irradiation

A number of methods are proposed for encapsulating silver and gold nanoparticles into shells of polyelectrolyte microcapsules for the purpose of increasing the sensitivity of microcapsules to laser radiation. It is shown that capsules with nanocomposite shells can be remotely damaged under laser radiation with different powers and wavelengths. The sensitivity of capsules with silver and gold nanoparticles in shells to this radiation can be controlled by varying the conditions used for the preparation of the capsules. The release of the encapsulated material under laser radiation makes these systems promising for use as microcontainers intended for the target delivery of drugs in an organism.

Permeability adjustment of polyelectrolyte micro-and nanocapsules by laser irradiation

Laser radiation was used for permeability increase up to destroy of polyelectrolyte capsules. Silver and gold nanoparticles was synthesized and incorporated into capsule shells to attain the sensitivity of microcapsules to laser radiation. Lasers of different power and wavelength were used. The sensitivity of nanocomposite shell to laser radiation can be controlled by nanoparticle shape, content and distribution into the shell.

Multifunctional microcontainers with tuned permeability for delivery and (bio)chemical reactions

Publisher Summary Small molecules could be easily handled, stored, delivered, and released from polyelectrolyte capsules. In order to make polyelectrolyte capsule a universe delivery platform, its permeability needs to be controlled. On the one hand, for efficient small-molecule encapsulation, the permeability of capsules should be significantly decreased. On the other hand, once the capsule reaches its target, the release of encapsulated materials needs to be triggered. These two functions—reducing permeability of capsules for encapsulation and subsequent release, collectively called tuning capsule permeability—are the subject of this chapter. This chapter demonstrates the possibility of entraping water-soluble molecular species into polyelectrolyte capsules modified by low-permeable dense polymers, e.g. polypyrrole, and various schemes for subsequent release of encapsulated materials. Future applications of polyelectrolyte capsules, such as carriers for gases, volatiles and, biomedically relevant molecules in pharmacy, food and gas industries, agriculture, and cosmetology, are also discussed.