Nanocomposite based on Gd2O3 nanoparticles and drug 5-fluorouracil as potential theranostic nano-cargo system

We have prepared silica matrix with hexagonal symmetry of pores (SBA-15) and loaded it with anticancer drug 5-Fluorouracil (5-FU) to promote it as a drug delivery system. Gd2O3 nanoparticles were incorporated into the matrix to enhance nanosystems applicability as contrast agent for MRI, thus enabled this nanocomposite to be used as multifunctional nano-based therapeutic agent. Drug release profile was obtained by UV-VIS spectroscopy, and it indicates the prolongated release of 5-FU during the first hours and the total release after 5 h. The cytotoxicity tests using MTT-assay, fluorescent microscopy, bright-field microscopy, and flow cytometry were carried out using human glioma U87 MG cells and SK BR 3 cells. The nanocomposite with anticancer drug (Gd2O3/SBA-15/5FU) showed toxic behaviour towards studied cells, unlike nanocomposite without drug (Gd2O3/SBA-15) that was non-toxic. Our drug delivery system was designed to minimalize negative effect of Gd3+ ions at magnetic resonance imaging and drug 5-FU on healthy cells due to their encapsulation into biocompatible silica matrix, so the Gd3+ ions are more stable (in comparison to chelates), lower therapeutic dose of 5-FU is needed and its prolongated release from silica pores was confirmed. Very good T1 contrast in MR images was observed even at low concentrations, thus this nanosystem can be potentially used as contrast imaging agent.

Adsorption and Release Properties of Drug Delivery System Naproxen-SBA-15: Effect of Surface Polarity, Sodium/Acid Drug Form and pH

Mesoporous silica SBA-15 was prepared via sol-gel synthesis and functionalized with different types of organosilanes containing various organic functional groups: (3-aminopropyl)triethoxysilane (SBA-15-NH₂), (3-mercaptopropyl)triethoxysilane (SBA-15-SH), triethoxymethylsilane (SBA-15-CH₃), triethoxyphenylsilane (SBA-15-Ph), and (3-isocynatopropyl)triethoxysilane (SBA-15-NCO). The prepared materials were investigated as drug delivery systems for naproxen. As model drugs, naproxen acid (HNAP) and its sodium salt (NaNAP) were used. Mentioned medicaments belong to the group of non-steroidal anti-inflammatory drugs (NSAIDs). The prepared materials were characterized by different analytical methods such as transmission electron microscopy (TEM), infrared spectroscopy (IR), nitrogen adsorption/desorption analysis (N₂), thermogravimetric analysis (TG), ¹H, ¹³C and ²³Na solid-state nuclear magnetic resonance spectroscopy (¹H, ¹³C and ²³Na ss-NMR). The abovementioned analytical techniques confirmed the successful grafting of functional groups to the SBA-15 surface and the adsorption of drugs after the impregnation process. The BET area values decreased from 927 m² g^-1 for SBA-15 to 408 m² g^-1 for SBA-15-NCO. After drug encapsulation, a more significant decrease in surface area was observed due to the filling of pores with drug molecules, while the most significant decrease was observed for the SBA-15-NH₂ material (115 m² g^-1 for NaNAP and 101 m² g^-1 for HNAP). By combining TG and nitrogen adsorption results, the occurrence of functional groups and the affinity of drugs to the carriers' surface were calculated. The dominant factor was the volume of functional groups and intermolecular interactions. The highest drug affinity values were observed for phenyl and amine-modified materials (SBA-15-Ph = 1.379 μmol m^-2 mmol^-1 for NaNAP, 1.761 μmol m^-2 mmol^-1 for HNAP and SBA-15-NH₂ = 1.343 μmol m^-2 mmol^-1 for NaNAP, 1.302 μmol m^-2 mmol^-1 for HNAP) due to the formation of hydrogen bonds and π-π interactions, respectively. Drug release properties and kinetic studies were performed at t = 37 °C (normal human body temperature) in different media with pH = 2 as simulated human gastric fluid and pH = 7.4, which simulated a physiological environment. Determination of drug release quantity was performed with UV-VIS spectroscopy. The surface polarity, pH and naproxen form influenced the total released amount of drug. In general, naproxen sodium salt has a higher solubility than its acid form, thus significantly affecting drug release from surface-modified SBA-15 materials. Different pH conditions involved surface protonation and formation/disruption of intermolecular interactions, influencing both the release rate and the total released amount of naproxen. Different kinetic models, zero-order, first-order, Higuchi and Hixson-Crowell models, were used to fit the drug release data. According to the obtained experimental results, the drug release rates and mechanisms were determined.

In vivo study of light-driven naproxen release from gated mesoporous silica drug delivery system

A drug delivery system based on mesoporous particles MCM-41 was post-synthetically modified by photo-sensitive ligand, methyl-(2E)-3-(4-(triethoxysilyl)-propoxyphenyl)-2-propenoate (CA) and the pores of MCM-41 particles were loaded with Naproxen sodium salt (NAP). The CA was used as a photoactive molecule that can undergo a reversible photo-dimerization by [2π + 2π] cycloaddition when irradiated with UV light of specific wavelengths. Thus, it has a function of gate-keeper that is responsible for opening/closing the pores and minimizing premature release of NAP. The physicochemical properties of the prepared system were studied by infrared spectroscopy (IR), nitrogen adsorption measurements, thermogravimetric analysis (TGA), scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDX). The mechanism of the opening/closing pores was confirmed by UV measurements. In vitro and in vivo drug release experiments and the concentration of released NAP was determined by UV spectroscopy and high-performance liquid chromatography (HPLC). In vivo drug release in the blood circulatory system of rats has demonstrated the effective photo-cleavage reaction of CA molecules after UV-light stimulation. The localization and morphological changes of the particles were studied in the blood and liver of rats at different time intervals. The particles in the blood have been shown to retain their original rod-like shape, and the particles in the liver have been hydrolysed, which has resulted in spherical shape with a reduced size.

Cytotoxicity study and influence of SBA-15 surface polarity and pH on adsorption and release properties of anticancer agent pemetrexed

Mesoporous material SBA-15 was functionalized with different polar and nonpolar groups: 3-aminopropyl, (SBA-15-NH₂), 3-isocyanatopropyl (SBA-15-NCO), 3-mercaptopropyl (SBA-15-SH), methyl (SBA-15-CH₃) and phenyl (SBA-15-Ph). The resulting surface grafted materials were investigated as matrices for controlled drug delivery. Anticancer agent, pemetrexed (disodium pemetrexed heptahydrate) was selected as a model drug and loaded in the unmodified and functionalized SBA-15 materials. Materials were characterized by elemental analysis, infrared spectroscopy, transmission electron microscopy, nitrogen adsorption/desorption analysis, small angle X-ray scattering, powder X-ray diffraction, solid state NMR spectroscopy and thermogravimetry. It was shown that surface modification has an impact on both encapsulated drug amount and release properties. Release experiments were performed into two media with different pH: simulated body fluid (pH = 7.4) and simulated gastric fluid (pH = 2). In general, the effect of pH was reflected by the lower release of pemetrexed under acidic conditions (pH = 2) compared to slightly alkaline saline environment (pH = 7.4). The release rate of pemetrexed from propylamine-, propylisocyanate- and phenyl-modified SBA-15 was found to be effectively controlled by intermolecular interactions as compared to that from pure SBA-15, SBA-15-SH, and SBA-15-CH₃, that evidenced a steady and similar release. The highest release was observed for methyl-functionalized material whose hydrophobic surface accelerates the pemetrexed release. The data obtained from release studies were fitted using various kinetic models to determine the pemetrexed release mechanism and its release rate. The best correlations were found for Korsmeyer-Peppas and Higuchi models. Moreover, the theoretical three-parameter model for drug release kinetic was applied to calculate the strength of drug-support interactions. The in vitro cell study was performed on SKBR3 cancer cells and obtained results demonstrated that the modification of the mesoporous silica material by grafted polar/nonpolar groups may significantly affect the compatibility of this material with cells, drug release from this material and subsequent biological activity of PEM.

Photo-switchable nanoporous silica supports for controlled drug delivery

A stimuli-responsive drug delivery system consisting of SBA-12 nanoporous silica modified with a photo-switchable coumarin ligand was studied for the delivery of the non-steroidal anti-inflammatory drug naproxen.

A drug delivery system based on switchable photo-controlled p-coumaric acid derivatives anchored on mesoporous silica

Mesoporous silica modified by p-coumaric acid derivatives as photo-switchable ligands was studied for the delivery of a non-steroidal anti-inflammatory drug.

Nutrition interventions in patients with Crohn´s disease

Crohn's disease is a chronic non-specific inflammatory bowel disease of any part of the digestive tract. The seriousness of the disease requires a multi-disciplinary approach when providing patients with secondary and tertiary care. Patients also have specific problems from the nursing perspective that require intervention of nurses, e.g. in the area of nutrition. The role of a nurse in a specific community lies in supporting public health in the field of prevention, health education, group educational activities and care of the acutely or chronically ill. The regulation tool of nursing practice when providing community care is the documented form of nursing data expressed by means of expert terminology. The Omaha System is a standardised terminology for multi-disciplinary teams providing community care. The objective of the research is to draw attention to the possibility of using standardised terminology of the Omaha System when supporting public health in patients with Crohn's disease with nutrition problems. The research was divided into 3 stages: in the first stage we assessed the nutrition problem in 100 patients dispensarised in gastroenterology counselling centres using a form from the Omaha System. Out of these, identified 42 patients suffered from Crohn's disease and had problems with nutrition; in the second stage we chose interventions for nutrition from the Intervention Scheme of the Omaha System: their efficiency in patients was assessed by a nurse/nutritionist in the third stage of the research when the patients came to the gastroenterology counselling centre using Problem Rating Scale for Outcomes. When comparing the initial and final nutrition assessment with socio-demographic indicators we found a statistically significant difference (p = 0.000) between the status assessment where women scored a more remarkable advance than men when comparing the initial and the final assessment. With respect to age groups, education and jobs, no statistically significant differences were found (p >0.05). Nutrition interventions, according to the Omaha System, are linked to administering enteral and parenteral nutrition, monitoring of nutrition condition and education, management and consultancy during the diet that is individual and dependent on various factors.