Zinc-doped hydroxyapatite as a pH responsive drug delivery system for anticancer drug 6-mercaptopurine.

6-Mercaptopurine (6MP) is commonly used in the treatment of acute lymphoblastic leukemia as an important agent in maintenance therapy. Despite its therapeutic benefits, 6MP has some limitations during therapy. Taking into account the disadvantages during 6MP therapy, there is a great need to create an appropriate delivery system for this drug. 6MP contains in its structure nitrogen and sulfur atoms capable of forming coordination compounds with metal ions, for example zinc. Therefore, in this work, we prepared biocompatible hydroxyapatite (HAp) doped with zinc ions, and used it as a carrier for 6MP. Doped HAp has not been used as a carrier for this drug before. The work proved that the prepared carrier-drug system has a particle size of about 130 nm, which indicates its potential for intravenous delivery. In addition, in an acidic environment (imitating cancer cells), the carrier agglomerates allow targeted release of the drug. The drug is evenly distributed, which indicates that the doses released from it will always be comparable. The release of the drug in a neutral environment is long-lasting in controlled doses, whereas in an acidic environment it is immediate. The obtained results indicate the high potential of the material in both slow-release and cancer-targeted release of 6MP.

Double Hydroxyl Salt as Smart Biocompatible pH-Responsive Carrier for 6-Mercaptopurine.

Hydroxy double salts are layered materials that are considered to be biocompatible. For this reason, research has been initiated on the possibility of their use in drug delivery. Despite their use for several types of drugs, their potential for controlled release of mercaptopurine (MERC) has not been studied. In this work, the synthesized hydroxy double salt (HDS) material was used as a carrier for this drug for the first time. The effectiveness of HDS synthesis has been proven by such techniques as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Based on the FT-IR and energy-dispersive X-ray spectroscopy (EDS) results, the effectiveness of drug sorption was proven. The exact amount of drug retained was determined by the UV-Vis technique. The obtained results indicate that the drug is evenly distributed on the surface of the carrier, which is important during the controlled delivery of drugs. In the most important stage of the research, the effectiveness of drug release in response to changes in the pH of the environment was proven. The drug is not released into an environment that mimics healthy human tissues. It is released only after contact with the acidic environment that usually surrounds cancer cells. The low cellular toxicity of HDS and significant cytotoxic effect of HDS-MERC were confirmed by in vitro studies on MCF-7 human breast and DU145 prostate cancer cell lines and non-cancerous keratinocytes HaCaT. Interestingly, coupling with the HDS carrier increased the cytotoxic effect of MERC towards DU145 cells. Such an "intelligent" drug carrier for mercaptopurine has not been previously described in the literature. The obtained results indicate its great potential.

Surface Modification of Ti6Al4V ELI Titanium Alloy by Poly(ethylene-alt-maleic anhydride) and Risedronate Sodium.

With the simultaneous increase in the number of endoprostheses being performed, advances in the field of biomaterials are becoming apparent-whereby the materials and technologies used to construct implants clearly improve the implants' quality and, ultimately, the life of the patient after surgery. The aim of this study was to modify the titanium alloy Ti6Al4V ELI used in the construction of hip joint endoprostheses. This is why the continuous development of biomaterials is so important. This paper presents the results of research for a new application of polymer poly(ethylene-alt-maleic anhydride) as a drug release layer, placed on the surface of a titanium alloy. The obtained layers were analyzed using Raman spectroscopy (spectra and maps), Fourier transform infrared spectroscopy (spectra and maps), contact angle measurements as well as scanning electron microscopy and energy dispersive spectroscopy imaging and topography analysis. The results confirmed that the polymer layer obtained on the plate surface after the alkali heat treatment process is much better-it binds much more polymer and thus the applied drug. In addition, a longer and more gradual release of the drug was observed for the alkali heat treatment modification than for H2O2 solution.

Zeolites with Divalent Ions as Carriers in the Delivery of Epigallocatechin Gallate.

Epigallocatechin gallate (EGCG) is a compound with very high therapeutic potential in the treatment of osteoporosis and cancer. The disadvantages of this compound are its low stability and low bioavailability. Therefore, carriers for EGCG are sought to increase its use. In this work, new carriers are proposed, i.e., zeolites containing divalent ions of magnesium, calcium, strontium, and zinc in their structure. EGCG is retained on the carrier surface by strong interactions with divalent ions. Due to the presence of strong interactions, EGCG is released in a controlled manner from the carrier-ion-EGCG drug delivery system. The results obtained in this work confirm the effectiveness of the preparation of new carriers. EGCG is released from the carriers depending on the pH; hence, it can be used both in osteoporosis and in the treatment of cancer. The divalent ion used affects the sorption and release of the drug. The obtained results indicate the great potential of the proposed carriers and their advantage over the carriers described in the literature.

Mesoporous Silica Modified with Polydopamine and Zinc Ions as a Potential Carrier in the Controlled Release of Mercaptopurine.

Mercaptopurine is one of the drugs used in the treatment of acute lymphoblastic leukemia. A problem with mercaptopurine therapy is its low bioavailability. This problem can be solved by preparing the carrier that releases the drug in lower doses but over a longer period of time. In this work, polydopamine-modified mesoporous silica with adsorbed zinc ions was used as a drug carrier. SEM images confirm the synthesis of spherical carrier particles. The particle size is close to 200 nm, allowing for its use in intravenous delivery. The zeta potential values for the drug carrier indicate that it is not prone to agglomeration. The effectiveness of drug sorption is indicated by a decrease in the zeta potential and new bands in the FT-IR spectra. The drug was released from the carrier for 15 h, so all of the drug can be released during circulation in the bloodstream. The release of the drug from the carrier was sustained, and no 'burst release' was observed. The material also released small amounts of zinc, which are important in the treatment of the disease because these ions can prevent some of the adverse effects of chemotherapy. The results obtained are promising and have great application potential.

Zeolitic Imidazolate Framework­8 (ZIF-8) modified titanium alloy for controlled release of drugs for osteoporosis.

The aim of this work was to prepare a biocompatible implant material that enables the release of drug for osteoporosis-risedronate. To achieve this goal, a titanium implant coated with a biocompatible Zeolitic Imidazolate Framework 8 (ZIF-8) layer was prepared that promotes osseointegration at the bone-implant interface. The modifications of the titanium alloy as well as sorption and desorption processes were confirmed using a variety of methods: SEM, EDS XPS, and FT-IR imaging (to determine surface modification, drug distribution, and risedronate sorption), and UV-Vis spectroscopy (to determine drug sorption and release profile). Both the ZIF-8 layer and the drug are evenly distributed on the surface of the titanium alloy. The obtained ZIF-8 layer did not contain impurities and zinc ions were strongly bounded by ZIF-8 layer. The ZIF-8 layer was stable during drug sorption. The drug was released in small doses for 16 h, which may help patients recover immediately after surgery. This is the first case of using ZIF-8 on the surface of the titanium alloy as carrier that releases the drug under the influence of body fluids directly at the site of the disease. It is an ideal material for implants designed for people suffering from osteoporosis.

Ionic liquid-assisted synthesis of chitin-ethylene glycol hydrogels as electrolyte membranes for sustainable electrochemical capacitors.

A novel chitin-ethylene glycol hybrid gel was prepared as a hydrogel electrolyte for electrical double-layer capacitors (EDLCs) using 1-butyl-3-methylimidazolium acetate [Bmim][Ac] as a chitin solvent. Examination of the morphology and topography of the chitin-EG membrane showed a homogeneous and smooth surface, while the thickness of the membrane obtained was 27 µm. The electrochemical performance of the chitin-EG hydrogel electrolyte was investigated by cyclic voltammetry and galvanostatic charge/discharge measurements. The specific capacitance value of the EDLC with chitin-EG hydrogel electrolyte was found to be 109 F g-1 in a potential range from 0 to 0.8 V. The tested hydrogel material was electrochemically stable and did not decompose even after 10,000 GCD cycles. Additionally, the EDLC test cell with chitin-EG hydrogel as electrolyte exhibited superior capacitance retention after 10,000 charge/discharge cycles compared with a commercial glass fiber membrane.