APTES monolayer coverage on self-assembled magnetic nanospheres for controlled release of anticancer drug Nintedanib.

The use of an appropriate delivery system capable of protecting, translocating, and selectively releasing therapeutic moieties to desired sites can promote the efficacy of an active compound. In this work, we have developed a nanoformulation which preserves its magnetization to load a model anticancerous drug and to explore the controlled release of the drug in a cancerous environment. For the preparation of the nanoformulation, self-assembled magnetic nanospheres (MNS) made of superparamagnetic iron oxide nanoparticles were grafted with a monolayer of (3-aminopropyl)triethoxysilane (APTES). A direct functionalization strategy was used to avoid the loss of the MNS magnetization. The successful preparation of the nanoformulation was validated by structural, microstructural, and magnetic investigations. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) were used to establish the presence of APTES on the MNS surface. The amine content quantified by a ninhydrin assay revealed the monolayer coverage of APTES over MNS. The monolayer coverage of APTES reduced only negligibly the saturation magnetization from 77 emu/g (for MNS) to 74 emu/g (for MNS-APTES). Detailed investigations of the thermoremanent magnetization were carried out to assess the superparamagnetism in the MNS. To make the nanoformulation pH-responsive, the anticancerous drug Nintedanib (NTD) was conjugated with MNS-APTES through the acid liable imine bond. At pH 5.5, which mimics a cancerous environment, a controlled release of 85% in 48 h was observed. On the other hand, prolonged release of NTD was found at physiological conditions (i.e., pH 7.4). In vitro cytotoxicity study showed dose-dependent activity of MNS-APTES-NTD for human lung cancer cells L-132. About 75% reduction in cellular viability for a 100 µg/mL concentration of nanoformulation was observed. The nanoformulation designed using MNS and monolayer coverage of APTES has potential in cancer therapy as well as in other nanobiological applications.

A green approach for the synthesis of α-Fe2O3 nanoparticles from Gardenia resinifera plant and it's In vitro hyperthermia application.

The Gardenia, traditional medicinal plant used from ancient time to increase appetite and other medicinal uses has been employed for the synthesis of superparamagnetic α-Fe2O3 nanoparticles (NPs). The plant extracts unveiled its bifunctional nature through the reducing ferric ions by phenolic groups and capping nature through the -OH bonding over the NPs surface. The prepared NPs exhibits α-Fe2O3 phase among iron oxides and spherical morphology with an average size around 5 nm. The magnetic measurements proved the superparamagnetic behavior of NPs with non-saturating MS value of 8.5 emu/g at room temperature (300 K). Further, the hyperthermia study reveals, the NPs achieved a temperature of 40 °C and 43 °C within 6 min and reaches up to 43 °C and 45 °C within 10 min only for 5 µg/mL and 10 µg/mL concentrations respectively. Based on the heating profile of NPs, the SAR values (167.7 Oe, 300 MHz) calculated and are found to be around 62.75 W/g and 24.38 W/g for 5 µg/mL and 10 µg/mL NPs concentrations respectively. Subsequently, these have been used for toxicity assays, which presented enhanced cytotoxic effects on human mesenchymal cells lines proving them as a potential candidate for the biomedical applications.

Monolayer grafting of aminosilane on magnetic nanoparticles: An efficient approach for targeted drug delivery system.

Magnetic nanoparticles (MNPs) with higher magnetization are highly desirable for targeted drug delivery (TDD) systems, as it helps accumulation of drug at the target site. However, functionalization of MNPs for drug binding reduces the magnetization which affects the efficacy of TDD. Herein we report direct functionalization of MNPs with (3-Aminopropyl)triethoxysilane (APTES) which preserves the magnetization. Grafting density estimated by TGA and BET analysis showed monolayer grafting of APTES on MNP surface. MNPs were comprehensively characterized by XRD, HR-TEM, SQUID-VSM and FTIR. Anti-cancerous drug telmisartan (TEL) was loaded on monolayer APTES grafted MNPs. In-vitro controlled drug release and cytotoxicity study on PC-3 human prostate cancer cell line of TEL conjugated MNPs are also discussed. This functionalization strategy can be extended to other biomedical applications where higher magnetization is desired.

Magnetic nanoparticle decorated graphene based electrochemical nanobiosensor for H2O2 sensing using HRP.

To utilize synergetic effect of graphene's higher conductivity and magnetic nanoparticles biocompatibility, an electrochemical nanobiosensor is constructed based on magnetic nanoparticle decorated graphene (MRGO) using Horseradish peroxidase (HRP) for H2O2 sensing. Sensors based on magnetic nanoparticles (MNP) and reduced graphene oxide (RGO) are studied for comparison. MNP, RGO and MRGO were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). XRD studies have confirmed successful synthesis of Fe3O4 MNPs, RGO and MRGO. TEM micrographs revealed uniform decoration of MNPs on graphene. FTIR confirmed the immobilization of HRP on MNP, RGO and MRGO. The MRGO based sensor exhibited higher sensitivity (48.08 µA µM-1 cm-2) compared to MNP (39.08 µA µM-1 cm-2) and RGO (41.08 µA µM-1 cm-2) based biosensors.

Immobilization of invertase on chitosan coated γ-Fe2O3 magnetic nanoparticles to facilitate magnetic separation.

Industrially important invertase enzyme was immobilized on chitosan coated sol gel derived γ-Fe2O3 magnetic nanoparticles (MNPs) to enable it for repetitive use by magnetic separation. MNPs were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), field emission scanning electron microscope (FE-SEM), Fourier transform infrared (FTIR) spectrometer and magnetic measurements. FTIR studies confirmed successful immobilization of invertase on MNPs. The ability to convert sucrose into invert syrup was enhanced in immobilized invertase compared to that of free enzyme. Further it was found that invertase immobilized on MNPs (IIMNPs) were more stable at varying pH and temperature conditions. Magnetic separation technique was successfully employed for reuse of the IIMNPs for 20 times without significant loss of activity.