Synthesis and activation of pH-sensitive metal-organic framework Sr(BDC)∞ for oral drug delivery

Metal-organic frameworks (MOFs) are widely used in the biomedical industry. In this study, we developed a new method for obtaining a metal-organic structure of strontium and terephthalic acid, Sr(BDC), and an alternative activation method for removing DMF from the pores. Sr(BDC) MOFs were successfully prepared and characterized by XRD, FTIR, TGA, and SEM. The importance of the activation steps was confirmed by TGA, which showed that the Sr(BDC)(DMF) sample can contain up to a quarter of the solvent (DMF) before activation. In our study, IR spectroscopy confirmed the possibility of removing DMF by ethanol treatment from the Sr-BDC crystals. A comparative analysis of the effect of the activation method on the specific surface and pore size of Sr-BDC and its sorption properties using the model drug doxorubicin showed that due to the undeveloped surface of the Sr-(BDC)(DMF) sample, it is not possible to obtain an adsorption isotherm and determine the pore size distribution, thus showing the importance of the activation step. Cytotoxicity and apoptosis assays were carried out to study the biological activity of MOFs, and we observed relatively low toxicity in the tested concentration range after 48 h, with over 92% cell survival for Sr(BDC)(DMF) and Sr(BDC)(260 °C), with a decrease only in the highest concentration (800 mg L-1). Similar results were observed in our apoptosis assays, as they revealed low apoptotic population generation of 2.52%, 3.23%, and 2.77% for Sr(BDC)(DMF), Sr(BDC) and Sr(BDC)(260 °C), respectively. Overall, the findings indicate that ethanol-activated Sr(BDC) shows potential as a safe and effective material for drug delivery.

Applicability of Electron-Beam and Hybrid Plasmas for Polyethylene Terephthalate Processing to Obtain Hydrophilic and Biocompatible Surfaces

The applicability of beam-plasma chemical reactors generating cold hybrid plasma for the production of noncytotoxic polymeric surfaces with high hydrophilicity and good biocompatibility with human fibroblast culture and human red blood cells was studied. Oxygen hybrid plasma was excited by the joint action of a continuous scanning electron beam and a capacity-coupled RF-gas discharge. Experiments showed that hybrid plasma treatment caused polar oxygen-containing functional group formation in the surface layer of poly (ethylene terephthalate) films. No thermal or radiative damage in tested polymer samples was found. The plasma-modified polymers turned out to be noncytotoxic and revealed good biocompatibility with human fibroblasts BJ-5ta as well as lower hemolytic activity than untreated poly (ethylene terephthalate). Experiments also demonstrated that no phenomena caused by the electrostatic charging of polymers occur in hybrid plasma because the electron beam component of hybrid plasma eliminates the item charge when it is treated. The electron beam can effectively control the reaction volume geometry as well as the fluxes of active plasma particles falling on the item surface. This provides new approaches to the production of abruptly structured patterns or smooth gradients of functionalities on a plane and 3D polymeric items of complicated geometry.

Box-Behnken assisted development and validation of high-performance liquid chromatography method for the simultaneous determination of doxorubicin and vorinostat in polymeric nanoparticles

While histone deacetylase inhibitors, such as vorinostat, demonstrate a significant effect against hematological cancers, their application for solid tumor treatment is limited. However, there is strong evidence that combinatorial administration of vorinostat and genotoxic agents (e.g., doxorubicin) enhances the antitumoral action of both drugs against tumors. We developed a high-performance liquid chromatography method for the simultaneous determination of doxorubicin and vorinostat in polymeric nanoparticles designed to provide the parenteral administration of both drugs and increase their safety profile. We performed separation on Nucleodur C-18 Gravity column with a mixture of 10 mM potassium dihydrogen phosphate buffer pH 3.9:ACN (90:10 v/v) as mobile phase at 240 nm. The method was linear within the concentration range of 4.2-52.0 μg/ml for both drugs with limits of detection and quantification of 3.5 and 10.7 μg/ml for doxorubicin and 2.5 and 7.7 μg/ml for vorinostat, respectively. The method was precise and accurate over the concentration range of analysis. Drug loading was 5.4% for doxorubicin and 0.8% for vorinostat. Degradation of doxorubicin after irradiation was less than 5%, while the amount of vorinostat decreased at 88% under the same conditions. Thus, the validated method could be adopted for routine simultaneous analysis of doxorubicin and vorinostat in polymeric nanoparticles.

Oxidative Damage Induced by Phototoxic Pheophorbide a 17-Diethylene Glycol Ester Encapsulated in PLGA Nanoparticles

Pheophorbide a 17-diethylene glycol ester (XL-8), is a promising high-active derivative of known photosensitizer chlorin e6 used in photodynamic therapy. However, high lipophilicity and poor tumor accumulation limit XL-8 therapeutic application. We developed a novel XL-8 loaded with poly(D,L-lactide-co-glycolide) nanoparticles using the single emulsion-solvent evaporation method. The nanoparticles possessed high XL-8 loading content (4.6%) and encapsulation efficiency (87.7%) and a small size (182 ± 19 nm), and negative surface charge (-22.2 ± 3.8 mV) contributed to a specific intracellular accumulation. Sustained biphasic XL-8 release from nanoparticles enhanced the photosensitizer photostability upon irradiation that could potentially reduce the quantity of the drug applied. Additionally, the encapsulation of XL-8 in the polymer matrix preserved phototoxic activity of the payload. The nanoparticles displayed enhanced cellular internalization. Flow cytometry and confocal laser-scanning microscopy studies revealed rapid XL-8 loaded nanoparticles distribution throughout the cell and initiation of DNA damage, glutathione depletion, and lipid peroxidation via reactive oxygen species formation. The novel nanoformulated XL-8 simultaneously revealed a significant phototoxicity accompanied with enhanced photostability, in contrast with traditional photosensitizers, and demonstrated a great potential for further in vivo studies.

Optimization, Characterization and Pharmacokinetic Study of Meso-Tetraphenylporphyrin Metal Complex-Loaded PLGA Nanoparticles

The selection of technological parameters for nanoparticle formulation represents a complicated development phase. Therefore, the statistical analysis based on Box-Behnken methodology is widely used to optimize technological processes, including poly(lactic-co-glycolic acid) nanoparticle formulation. In this study, we applied a two-level three-factor design to optimize the preparation of nanoparticles loaded with cobalt (CoTPP), manganese (MnClTPP), and nickel (NiTPP) metalloporphyrins (MeP). The resulting nanoparticles were examined by dynamic light scattering, X-ray diffraction, Fourier transform infrared spectroscopy, MTT test, and hemolytic activity assay. The optimized model of nanoparticle formulation was validated, and the obtained nanoparticles possessed a spherical shape and physicochemical characteristics enabling them to deliver MeP in cancer cells. In vitro hemolysis assay revealed high safety of the formulated MeP-loaded nanoparticles. The MeP release demonstrated a biphasic profile and release mechanism via Fick diffusion, according to release exponent values. Formulated MeP-loaded nanoparticles revealed significant antitumor activity and ability to generate reactive oxygen species. MnClTPP- and CoTPP-nanoparticles specifically accumulated in tissues, preventing wide tissue distribution caused by long-term circulation of the hydrophobic drug. Our results suggest that MnClTPP- and CoTPP-nanoparticles represent the greatest potential for utilization in in anticancer therapy due to their effectiveness and safety.

Expression of acid cleavable Asp-Pro linked multimeric AFP peptide in E. coli

Background

Difficult to express peptides are usually produced by co-expression with fusion partners. In this case, a significant mass part of the recombinant product falls on the subsequently removed fusion partner. On the other hand, multimerization of peptides is known to improve its proteolytic stability in E. coli due to the inclusion of body formation, which is sequence specific. Thereby, the peptide itself may serve as a fusion partner and one may produce more than one mole of the desired product per mole of fusion protein. This paper proposes a method for multimeric production of a human alpha-fetoprotein fragment with optimized multimer design and processing. This fragment may further find its application in the cytotoxic drug delivery field or as an inhibitor of endogenous alpha-fetoprotein.

Results

Multimerization of the extended alpha-fetoprotein receptor-binding peptide improved its stability in E. coli, and pentamer was found to be the largest stable with the highest expression level. As high as 10 aspartate-proline bonds used to separate peptide repeats were easily hydrolyzed in optimized formic acid-based conditions with 100% multimer conversion. The major product was represented by unaltered functional alpha-fetoprotein fragment while most side-products were its formyl-Pro, formyl-Tyr, and formyl-Lys derivatives. Single-step semi-preparative RP-HPLC was enough to separate unaltered peptide from the hydrolysis mixture.

Conclusions

A recombinant peptide derived from human alpha-fetoprotein can be produced via multimerization with subsequent formic acid hydrolysis and RP-HPLC purification. The reported procedure is characterized by the lower reagent cost in comparison with enzymatic hydrolysis of peptide fusions and solid-phase synthesis. This method may be adopted for different peptide expression, especially with low amino and hydroxy side chain content.

Supplementary Information

The online version contains supplementary material available at 10.1186/s43141-021-00265-5.