Polyhedral oligomeric silsesquioxanes (POSS) have attracted considerable attention in the design of novel organic-inorganic hybrid materials with high performance capabilities. Features such as their well-defined nanoscale structure, chemical tunability, and biocompatibility make POSS an ideal building block to fabricate hybrid materials for biomedical applications. This review highlights recent advances in the application of POSS-based hybrid materials, with particular emphasis on drug delivery, photodynamic therapy and bioimaging. The design and synthesis of POSS-based materials is described, along with the current methods for controlling their chemical functionalization for biomedical applications. We summarize the advantages of using POSS for several drug delivery applications. We also describe the current progress on using POSS-based materials to improve photodynamic therapies. The use of POSS for delivery of contrast agents or as a passivating agent for nanoprobes is also summarized. We envision that POSS-based hybrid materials have great potential for a variety of biomedical applications including drug delivery, photodynamic therapy and bioimaging.

Recently, inorganic nanomaterials have emerged as promising wettability modifiers to improve oil recovery. Among them, silica nanoparticles (SNPs) have gained a privileged place due to their outstanding properties. Several studies have reported the effectiveness of SNPs on this particular application. However, there is an increasing interest of understanding the parameters that may play an important role on oil recovery using nanofluids. The impact of particle size, particle concentration and types of nanoparticles on oil recovery have been reported. Nevertheless, to our knowledge, the influence of the surface charge has not been investigated. In this work, the effect of the surface charge of SNPs on oil recovery was studied. Silica nanoparticles with different charge profiles (negative, positive and slightly negative) were synthesized and characterized using transmission electron microscopy, FT-IR, dynamic light scattering and ζ-potential. Negatively charged nanoparticles (Neg-SNPs; − 33.45 ± 2.75) were obtained by following the Stöber process. The silanol groups present on the surface of the Neg-SNPs are responsible for the negative surface charge. Positively charged nanoparticles (AP-SNPs; + 42.25 ± 1.9) and slightly negatively charged nanoparticles (MeO-PEG-SNPs; − 12.20 ± 0.42) were obtained by grafting (3-aminopropyl) triethoxysilane and methoxy polyethylene glycol (MeO-PEG 2K) onto the surface of Neg-SNPs, respectively. The impact of silica materials with different charge profiles on wettability alteration and oil displacement at different concentrations (100 or 200 mg/L) was evaluated by contact angle estimation and spontaneous imbibition experiments. The results demonstrated that the surface charge of SNPs transformed the wettability of the sandstone cores and impacted oil recovery in a different extent. While MeO-PEG-SNPs showed the best performance at a low concentration, Neg-SNPs were the most effective in changing the rock wettability and removing oil from sandstone cores at a higher concentration. Overall, our results not only allowed to identify the impact of surface charge on oil recovery but also the effect of SNPs concentration on the suitability of the treatment for enhancing the oil recovery process.

Polyhedral oligomeric silsesquioxane (POSS) is a promising scaffold to be used as delivery system. POSS can modify the properties of photosensitizers to enhance their efficacy toward photodynamic therapy (PDT). In this work, we designed, synthesized and characterized five different POSS porphyrin (POSSPs 1–5) derivatives containing hydrophobic (1–3) and hydrophilic (4 and 5) functional groups. In general, all the POSSPs showed a better singlet oxygen quantum yield than the parent porphyrins due to the steric hindrance from the POSS unique structure. POSSPs 1 and 3 containing isobutyl groups showed better PDT performance in cancer cells at lower concentrations than POSSPs 4 and 5. However; at higher concentrations, the POSSP4 containing hydrophilic groups has an enhanced PDT efficiency as compared with the parent porphyrin. We envision that the chemical tunability of POSSs can be used as a promising option to improve the delivery and performance of photosensitizers.

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