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The combination of the mesoporous silica material SBA-1 5 with the temperature-responsive hydrogels, such as poly(N-isopropylacrylamide) P(N-iPAAm) can lead to the formation of a material with the potential for application as a new drug delivery system, given that self-regulated delivery allows for drug release when needed. The present work studies the synthesis and characterization of hybrid systems consisting of the poly(N-isopropylacrylamide) hydrogel and SBA-15 by varying the amount of hydrogel within the silica network. A systematic study on the structural properties of hybrid samples, their thermal stability and the degradation of the polymer chains in silica was carried out through characterization techniques, including SAXS, thermogravimetry and physical adsorption of N2. The results were critically examined and compared with pure SBA-15. The present study's results demonstrated that the thermosensibility of P(N-iPAAm) was retained in the hybrid system, which presented a low critical solution temperature, similar to that of pure P(N-iPAAm). Moreover, the hydrogel did not fully occupy the available intrachannel space, making the [SBA-15/P(N-iPAAm)] hybrids a very promising candidate for hosting and further delivery, under appropriate conditions, of a variety of molecules of pharmaceutical interest.

Theranostic systems integrate therapy and diagnosis in combination to achieve precise cancer treatment. At the same time, magnetic iron nanoparticles have emerged as advanced functional materials for a variety of biomedical applications. Additionally, rare-earth compounds have been crucial over the past decade due to their optical properties and low cytotoxicity for biological applications. Nanostructured materials such as mesoporous silica, which could be integrated with the previously mentioned materials, are ideal candidates for theranostic systems. In this study nanocomposites of mesoporous silica nanoparticles were obtained and tailored with rare earths and magnetite that exhibit both ferrimagnetism and photoluminescence properties as theranostic agents for cancer therapy. Structural, optical, and magnetic characterization were performed by infrared spectroscopy (FTIR), thermogravimetric analysis (TG), photoluminescence studies, zeta potential, X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). The capacity of heat generation (CHG) was measured using an Ameritherm heater (EasyHeat model) with an alternating magnetic field. The results show that the nanocomposites have ideal properties for magneto-hyperthermia applications and optical properties, making them promising as theranostic systems to treat diseases such as cancer. [ABSTRACT FROM AUTHOR]

We fabricated and characterized tailored nanocomposites of rare-earth orthoferrites (RFeO 3) (R = Nd and Y) and magnetite (Fe 3 O 4). The orthoferrites RFeO 3 (R = Nd and Y) were prepared by sol–gel synthesis and added during the co-precipitation synthesis of magnetite in three different nominal concentrations (RFeO 3 /Fe 3 O 4 : 90/10, 50/50, 10/90). X-ray diffraction, Mössbauer spectroscopy, vibrating-sample magnetometry, transmission electron microscopy, ultraviolet–visible spectroscopy, and infrared spectroscopy were employed for structural and magnetic characterizations. The composites exhibited mean particle size distributions in the range of 5–50 nm and a maximum specific absorption rate of 55 W g−1 after 30 min of exposure to an alternating magnetic field of 220 Oe. The results demonstrate that the nanocomposites have ideal characteristics for magneto-hyperthermia applications and thus are promising systems for the treatment of diseases such as cancer. [ABSTRACT FROM AUTHOR]