Liquid-crystal enabled electrophoresis: Scenarios for driving and reconfigurable assembling of colloids

We demonstrate several examples of driving and steering of colloids when dispersed in nematic liquid crystals. The driving mechanism is based on the principle of nonlinear electrophoresis which is mediated by the asymmetry in the structure of the defects that the inclusions generate in the host elastic matrix. The steering mechanism originates in the photoactivation of the anchoring conditions of the nematic liquid crystal on one of the enclosing plates. As experimental realizations we first review a scenario of water microdroplets being phoretically transported for cargo release and chemical reaction. Steering is illustrated in terms of the reconfigurable assembly of colloidal particles, either in the form of asters or rotating-mills, commanded by predesigned patterns of illumination

Structural modulation of the biological activity of gold nanoparticles functionalized with a carbonic anhydrase inhibitor

Gold nanoparticles (AuNPs) have gained attention for their potential and application in different fields, e.g. nanomedicine. This study explores the surface functionalization of AuNP with inhibitors of carbonic anhydrases (CAs, EC 4.2.1.1). Some CA transmembrane isoforms have been recognized as therapeutic targets for the treatment of hypoxic tumors. Embedding a CA inhibitory function onto a nanosized unit has been proved to enable selective targeting of transmembrane isoforms. We report the preparation in aqueous media, the characterization and CA inhibition tests of AuNPs coated with a sulfonamide (SA) derivative, already known for its inhibitory activity toward CAs. The physico-chemical characterization of SA-coated AuNPs was performed with a combination of scattering and spectroscopic techniques. We detect a threshold effect of the SA concentration on the final hydrodynamic and core sizes of the capped nanoparticles and on their stability over aggregation. These modified nanoparticles were assayed for inhibition of some CA transmembrane isoforms (CA IX and XII) as well as of two cytosolic isoforms (CA I and II), and show interesting inhibitory efficiency in the submicromolar range and some selectivity for transmembrane isoforms