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Ethionamide (ETH) is an important second-line antituberculosis drug used for the treatment of patients infected with multidrug-resistant Mycobacterium tuberculosis. Recently, we reported that the loading of ETH into thermally carbonized-porous silicon (TCPSi) nanoparticles enhanced the solubility and permeability of ETH at different pH-values and also increased its metabolization process. Based on these results, we synthesized carboxylic acid functionalized thermally hydrocarbonized porous silicon nanoparticles (UnTHCPSi NPs) conjugated with ETH and its antimicrobial effect was evaluated against Mycobacterium tuberculosis strain H37Rv. The activity of the conjugate was increased when compared to free-ETH, which suggests that the nature of the synergy between the NPs and ETH is likely due to the weakening of the bacterial cell wall that improves conjugate-penetration. These ETH-conjugated NPs have great potential in reducing dosing frequency of ETH in the treatment of multidrug-resistant tuberculosis (MDR-TB). (C) 2016 Elsevier Ltd. All rights reserved., Fundação para a Ciência e Tecnologia (FCT, Portugal) and FEDER (European Union) for funding through UID/MULTI/04378/2013, project grant IF/00092/2014 and IF2014 position. Thanks are also due to “Comissão de Coordenação e Desenvolvimento Regional do Norte (CCDR-N)/NORTE2020/Portugal 2020” for funding through project DESignBIOtechHealth (ref. Norte-01-0145-FEDER-000024). H.A.S. acknowledges financial support from the Academy of Finland (decision nos. 252215 and 281300), the University of Helsinki Research Funds, the Biocentrum Helsinki, and the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013, Grant No. 310892). The content is solely the responsibility of the authors and does not necessarily represent the official views of the FCT or CCDR-N, info:eu-repo/semantics/publishedVersion

Impediments to intestinal absorption, such as poor solubility and instability in the variable conditions of the gastrointestinal (GI) tract plague many of the current drugs restricting their oral bioavailability. Particulate drug delivery systems hold great promise in solving these problems, but their effectiveness might be limited by their often rapid transit through the GI tract. Here we describe a bioadhesive oral drug delivery system based on thermally-hydrocarbonized porous silicon (THCPSi) functionalized with a self-assembled amphiphilic protein coating consisting of a class II hydrophobin (HFBII) from Trichoderma reesei. The HFBII-THCPSi nanoparticles were found to be non-cytotoxic and mucoadhesive in AGS cells, prompting their use in a biodistribution study in rats after oral administration. The passage of HFBII-THCPSi nanoparticles in the rat GI tract was significantly slower than that of uncoated THCPSi, and the nanoparticles were retained in stomach by gastric mucoadhesion up to 3 h after administration. Upon entry to the small intestine, the mucoadhesive properties were lost, resulting in the rapid transit of the nanoparticles through the remainder of the GI tract. The gastroretentive drug delivery system with a dual function presented here is a viable alternative for improving drug bioavailability in the oral route.

This work reports on an electrochemical system which allows the control of surface wettability properties by voltage induced changes in contact angle (Θ) of ΔΘ ⩾ 50°. For this we used conductive TiO2 nanotubular layers that were modified with ferrocene coupled to the TiO2 surface via triethoxysilane. To enhance the hydrophobic character of the nanotubular TiO2 surface, also mixed organic monolayers namely perfluorotriethoxysilane, were explored. Formation of the ferrocene and mixed organic monolayer was confirmed by X-ray-photoelectron-spectroscopy (XPS). Contact angle combined with electrochemical measurements show that ferrocene in these monolayers can successfully be switched from Fe2+ to Fe3+ and that this change in the redox state considerably alters the wetting properties. Using a conductive nanotube substrate allows us to amplify this change by a factor of more than 10, and thus this surface can be used to trigger significant wetting alterations. Keywords: TiO2 nanotubes, Wetting, Self assembled monolayer, Ferrocene

Thermal stabilization is commonly used to stabilize porous silicon (PSi) for different applications. This chapter starts with an introduction to the history of different stabilization treatments, after which different thermal stabilization methods are described and discussed in detail. This chapter includes short overviews of how these stabilized PSi surfaces can be functionalized for biomedical applications.