Composite Central Face Design-An Approach to Achieve Efficient Alginate Microcarriers

Enhancement of Valsartan Oral Bioavailability by Preparing a Microwave-Irradiated Inclusion Complex with Sulfobutyl Ether β-Cyclodextrin Using a Central Composite Face Design for Optimising Process Parameters

The purpose of the study is to investigate the influence of sulfobutyl ether β-cyclodextrin (SBE₇-β-CD) on the bioavailability of valsartan. Phase solubility investigations showed an A_L type curve. The estimated apparent stability constant for valsartan SBE₇-β-CD is 427 ± 0.32 M^-1. Inclusion complexes of valsartan SBE₇-β-CD in equal molar ratio were prepared by microwave irradiation technique. The process parameters were optimised with a central composite face design. Response surface graphs and contour plots showed how process factors affected drug content. The inclusion complexes prepared by optimising process variables are characterised. The DSC and X-ray diffraction confirm the formation of inclusion complexes and the drug's transition from a crystalline to an amorphous state. FTIR suggests hydrogen bonding between valsartan and SBE₇-β-CD. SEM showed changes in drug morphology and shape. The dissolution rate of the prepared SBE₇-β-CD complex using microwave irradiation was 2.85 times that of pure valsartan. The inclusion complex was formulated into tablet dosage forms F₁ to F₄. Furthermore, oral bioavailability studies in rats with tablet formulation F₃ were carried out and compared to the marketed Diovan® tablet as a reference standard. The F₃ tablet formulation exhibited significantly higher values of AUC_0-∞ and C_max than the reference. Finally, the microwave-irradiated valsartan SBE₇-β-CD inclusion complex converted into tablet dosage form may be a promising approach to increasing valsartan oral bioavailability.

Hydroxypropyl methylcellulose-based micro- and nanostructures for encapsulation of melanoidins: Effect of electrohydrodynamic processing variables on morphological and physicochemical properties

Electrohydrodynamic processing (EHDP) allows the use of a wide range of biopolymers and solvents, including food-grade biopolymers and green solvents, for the development of micro- and nanostructures. These structures present a high surface-area-to-volume ratio and different shapes and morphologies. The aim of this work was to design and produce hydroxypropyl methylcellulose (HPMC)-based micro- and nanostructures through EHD processing using green solvents, while exploring the influence of process and solution parameters, and incorporating a bioactive extracted from a food by-product. Low (LMW) and high (HMW) molecular weight HPMC have been used as polymers. The design-of-experiments methodology was used to determine the effects of process parameters (polymer concentration, flow rate, tip-to-collector distance, and voltage) of EHDP on the particle and fibre diameter, aspect ratio, diameter distribution, aspect ratio distribution, and percentage of fibre breakage. Additionally, melanoidins extracted from spent coffee grounds were encapsulated into the HPCM-based structures at a concentration of 2.5 mg melanoidins/mL of the polymer solution. Polymer solutions were characterised regarding their viscosity, surface tension and conductivity, and showed that the incorporation of melanoidins increased the viscosity and conductivity values of the polymer solutions. The developed structures were characterised regarding their thermal properties, crystallinity and morphology before and after melanoidin incorporation and it was observed that melanoidin incorporation did not significantly influence the characteristics of the produced micro- and nanostructures. Based on the results, it is possible to envision the use of the produced micro- and nanostructures in a wide range of applications, both in food and biomedical fields.

Design of Experiments to Achieve an Efficient Chitosan-Based DNA Vaccine Delivery System

In current times, DNA vaccines are seen as a promising approach to treat and prevent diseases, such as virus infections and cancer. Aiming at the production of a functional and effective plasmid DNA (pDNA) delivery system, four chitosan polymers, differing in the molecular weight, were studied using the design of experiments (DoE) tool. These gene delivery systems were formulated by ionotropic gelation and exploring the chitosan and TPP concentrations as DoE inputs to maximize the nanoparticle positive charge and minimize their size and polydispersity index (PDI) as DoE outputs. The obtained linear and quadratic models were statistically significant (p-value < 0.05) and non-significant lack of fit, with suitable coefficient of determination and the respective optimal points successfully validated. Furthermore, morphology, stability and cytotoxicity assays were performed to evaluate the endurance of these systems over time and their further potential for future in vitro studies. The subsequent optimization process was successful achieved for the delivery systems based on the four chitosan polymers, in which the smallest particle size was obtained for the carrier containing the 5 kDa chitosan (~82 nm), while the nanosystem prepared with the high molecular weight (HMW) chitosan displayed the highest zeta potential (~+26.8 mV). Delivery systems were stable in the formulation buffer after a month and did not exhibit toxicity for the cells. In this sense, DoE revealed to be a powerful tool to explore and tailor the characteristics of chitosan/pDNA nanosystems significantly contributing to unraveling an optimum carrier for advancing the DNA vaccines delivery field.

A Pathway From Porous Particle Technology Toward Tailoring Aerogels for Pulmonary Drug Administration

Pulmonary drug delivery has recognized benefits for both local and systemic treatments. Dry powder inhalers (DPIs) are convenient, portable and environmentally friendly devices, becoming an optimal choice for patients. The tailoring of novel formulations for DPIs, namely in the form of porous particles, is stimulating in the pharmaceutical research area to improve delivery efficiency. Suitable powder technological approaches are being sought to design such formulations. Namely, aerogel powders are nanostructured porous particles with particularly attractive properties (large surface area, excellent aerodynamic properties and high fluid uptake capacity) for these purposes. In this review, the most recent development on powder technologies used for the processing of particulate porous carriers are described via updated examples and critically discussed. A special focus will be devoted to the most recent advances and uses of aerogel technology to obtain porous particles with advanced performance in pulmonary delivery.

ER, Venâncio T, Valderrama AC. Functionalization of an Alginate-Based Material by Oxidation and Reductive Amination

This research focused on the synthesis of a functional alginate-based material via chemical modification processes with two steps: oxidation and reductive amination. In previous alginate functionalization with a target molecule such as cysteine, the starting material was purified and characterized by UV-Vis, ¹H-NMR and HSQC. Additionally, the application of FT-IR techniques during each step of alginate functionalization was very useful, since new bands and spiked signals around the pyranose ring (1200–1000 cm⁻¹) and anomeric region (1000–750 cm⁻¹) region were identified by a second derivative. Additionally, the presence of C₁-H₁ of β-D-mannuronic acid residue as well as C₁-H₁ of α-L-guluronic acid residue was observed in the FT-IR spectra, including a band at 858 cm⁻¹ with characteristics of the N-H moiety from cysteine. The possibility of attaching cysteine molecules to an alginate backbone by oxidation and post-reductive amination processes was confirmed through ¹³C-NMR in solid state; a new peak at 99.2 ppm was observed, owing to a hemiacetal group formed in oxidation alginate. Further, the peak at 31.2 ppm demonstrates the presence of carbon -CH₂-SH in functionalized alginate—clear evidence that cysteine was successfully attached to the alginate backbone, with 185 μmol of thiol groups per gram polymer estimated in alginate-based material by UV-Visible. Finally, it was observed that guluronic acid residue of alginate are preferentially more affected than mannuronic acid residue in the functionalization.