Efficient removal of cationic dyes using lemon peel-chitosan hydrogel composite: RSM-CCD optimization and adsorption studies

The most prominent and easily identifiable factor of water purity is its colour, which may be both physically undesirable, and act as an alert towards potential environmental contamination. The current study describes the optimum synthesis technique for Lemon Peel-Chitosan hydrogel using the Response Surface Methodology integrated Central composite Design (RSM-CCD). This adsorbent is both environmentally friendly and cost-effective. The hydrogel exhibited a maximal dye removal capacity of 24.984, 24.788, 24.862, 23.483, 24.409, and 24.726 mg g-1, for 10 mg L-1 aqueous medium of Safranin O, Methylene blue, Basic fuchsin, Toluidine blue, Brilliant green and Crystal violet, respectively. The adsorption kinetics and isotherm data suggest that the Pseudo second-order kinetic and Freundlich adsorption isotherm models precisely represent the respective behaviour of all the dyes. The thermodynamic viability of the process is determined by the values of ΔG, ΔH, and ΔS. The probable mechanism of adsorption was the electrostatic interaction between the dye molecules and the hydrogel. The regenerated hydrogel had removal efficiencies of over 80 % even after enduring six cycles. Hence, the exceptional recyclability and utility of the adsorbent show their sustainability for wastewater treatment in textile factories.

A novel pH-responsive hydrogel system based on Prunus armeniaca gum and acrylic acid: Preparation and evaluation as a potential candidate for controlled drug delivery

pH-responsive hydrogels have become effective and attractive materials for the controlled release of drugs at pre-determined destinations. In the present study, a novel hydrogel system based on Prunus armeniaca gum (PAG) and acrylic acid (AA) was prepared by a free radical mechanism using N, N-methylene bisacrylamide (MBA) as cross-linker and potassium persulfate (KPS) as initiator. A series of hydrogels varying PAG, AA, and MBA concentration was developed to determine the impact of these components. Formulated hydrogels were characterized for pH-responsive swelling, drug release, gel content, and porosity. Structural analysis was performed by FTIR, XRD, and SEM analysis. TGA study was applied to assess thermal stability. Oral acute toxicity and in vivo drug release were performed in rabbits. Hydrogels exhibited pH-dependent swelling and drug release. Swelling, drug loading and release, and porosity increased by increasing PAG and AA concentration while decreased by increasing MBA. The gel content of formulations was increased by increasing all three components. FTIR studies confirmed the development of copolymeric networks and the loading of drug. XRD studies revealed that hydrogels were amorphous, and the crystalline drug was changed into an amorphous form during loading. TGA results indicated that hydrogels were stable up to 600 °C. Acute oral toxicity results confirm that hydrogels were nontoxic up to a dose of 2 g/kg body weight in rabbits. The pharmacokinetic evaluation revealed that hydrogels prolonged the availability of the drug and the peak plasma concentration of the drug was obtained in 6 h as compared to the oral solution of the drug. Tramadol hydrochloride (THC) was used as a model drug. Hence, pH-responsive swelling and release, nontoxic nature and improved pharmacokinetics support that PAG-based hydrogels may be considered as potential controlled-release polymeric carriers.

Plant-Based, Hydrogel-like Microfibers as an Antioxidant Platform for Skin Burn Healing

Natural polymers from organic wastes have gained increasing attention in the biomedical field as resourceful second raw materials for the design of biomedical devices which can perform a specific bioactive function and eventually degrade without liberating toxic residues in the surroundings. In this context, patches and bandages, that need to support the skin wound healing process for a short amount of time to be then discarded, certainly constitute good candidates in our quest for a more environmentally friendly management. Here, we propose a plant-based microfibrous scaffold, loaded with vitamin C (VitC), a bioactive molecule which acts as a protecting agent against UV damages and as a wound healing promoter. Fibers were fabricated via electrospinning from various zein/pectin formulations, and subsequently cross-linked in the presence of Ca2+ to confer them a hydrogel-like behavior, which we exploited to tune both the drug release profile and the scaffold degradation. A comprehensive characterization of the physico-chemical properties of the zein/pectin/VitC scaffolds, either pristine or cross-linked, has been carried out, together with the bioactivity assessment with two representative skin cell populations (human dermal fibroblast cells and skin keratinocytes, HaCaT cells). Interestingly, col-1a gene expression of dermal fibroblasts increased after 3 days of growth in the presence of the microfiber extraction media, indicating that the released VitC was able to stimulate collagen mRNA production overtime. Antioxidant activity was analyzed on HaCaT cells via DCFH-DA assay, highlighting a fluorescence intensity decrease proportional to the amount of loaded VitC (down to 50 and 30%), confirming the protective effect of the matrices against oxidative stress. Finally, the most performing samples were selected for the in vivo test on a skin UVB-burn mouse model, where our constructs demonstrated to significantly reduce the inflammatory cytokines expression in the injured area (50% lower than the control), thus constituting a promising, environmentally sustainable alternative to skin patches.

Biomaterials for Regenerative Medicine in Italy: Brief State of the Art of the Principal Research Centers

Regenerative medicine is the branch of medicine that effectively uses stem cell therapy and tissue engineering strategies to guide the healing or replacement of damaged tissues or organs. A crucial element is undoubtedly the biomaterial that guides biological events to restore tissue continuity. The polymers, natural or synthetic, find wide application thanks to their great adaptability. In fact, they can be used as principal components, coatings or vehicles to functionalize several biomaterials. There are many leading centers for the research and development of biomaterials in Italy. The aim of this review is to provide an overview of the current state of the art on polymer research for regenerative medicine purposes. The last five years of scientific production of the main Italian research centers has been screened to analyze the current advancement in tissue engineering in order to highlight inputs for the development of novel biomaterials and strategies.

Fabrication, Characterization and Toxicity Evaluation of Chemically Cross linked Polymeric Network for Sustained Delivery of Metoprolol Tartrate

Natural mucilages are auspicious biodegradable polymeric materials. The aim of the present research work was to elucidate the characteristics of quince mucilage-based polymeric network for sustained delivery of metprolol tartrate and its toxicity evaluation. Mucilage was extracted by hot water extraction, and characterization of quince mucilage was accomplished by using Fourier transform infrared (FTIR) spectroscopy. Different batches of quince mucilage polymeric network were prepared by free radical polymerization by utilizing varying ratios of quince mucilage, acrylamide and crosslinker. Degree of swelling depends on concentration of mucilage, monomer and also on crosslinking density of polymeric network. FTIR illustrates proficient grafting, and morphological (scanning electron microscopy) analysis signified porous design. Hence, quince mucilage-based design was encouraging for sustained delivery of metprolol tartrate and acute toxicity evaluation proved that mucilage-based network was safe for oral drug delivery system.

Pectin from Okra (Abelmoschus esculentus L.) Has Potential as a Drug Release Modifier in Matrix Tablets

Natural polymers have become attractive to pharmaceutical researchers and manufacturers as excipients because of the advantages they possess relative to their semisynthetic and synthetic counterparts. Although pectin from some natural sources has been investigated for use in the pharmaceutical industry as excipients, pectin from okra, which is readily available and used as food in many parts of the world, has not been extensively investigated as a potential control-releasing agent in tablets. This study thus seeks to determine the drug release modifying properties of okra pectin from 6 different genotypes of okra cultivated and available in Ghana. Pectin was extracted from different genotypes of okra, physicochemical properties were characterized, and control release matrix tablets of metformin (F1–F6) were formulated using the wet granulation method with the okra pectin as the drug release modifier, respectively. The drug content, in vitro drug release, and mathematical kinetic modeling of drug release from the matrix tablets were studied. Drug release profiles of formulated matrix tablets were compared to an existing (innovator) brand of metformin sustained-release tablet on the market using the similarity and difference factors, respectively. The extracted pectin had percentage yields ranging from 6 to 20% w/w with swelling indexes and water-holding capacities between 300–500% and 9-10 mL/g, respectively, and pH within 6.20–6.90. All the formulated batches passed the drug content test (90–105%) and produced the optimal release of metformin (>80%) after 24 hours. Different batches of formulated tablets exhibited different mechanisms of drug release with batches F1, F2, F5, and F6 being similar (ƒ₂ values being >50 and ƒ₁ values <15) to the innovator brand. Pectin from the 6 different genotypes of okra studied has the potential for use as drug release modifiers in pharmaceutical manufacturing of control release matrix tablets and production of more affordable medicines.

Fabrication and evaluation of polylactic acid/pectin composite scaffold via freeze extraction for tissue engineering

This work reports the fabrication and characterizations of porous scaffold made up of polylactic acid (PLA) with the inclusion of pectin (1, 3, 5, 7, 9, 11 wt%) for potential tissue engineering material. The composite scaffold was prepared using a facile method of freeze extraction. Based on the physical evaluations, the scaffold was suggested to be optimum at 5 wt% of pectin loading. Water contact angle of the scaffold was significantly reduced to 46.5o with the inclusion of 5 wt% of pectin. Morphological and topographic of the PLA scaffold revealed that the pectin induced more porous structure and its surface became rougher which was suitable for cell attachment and proliferation. In vitro studies of the PLA/pectin composite scaffold using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromidelt (MTT) assay revealed good biocompatibility whereas Live-Dead kit assay resulted in 91% cell viability after 7 days of incubation.

In vitro evaluation of Pt-coated electrospun nanofibers for endovascular coil embolization

Recently, endovascular coil embolization has been introduced to treat intracranial aneurysms because it has lower morbidity and mortality than surgical clipping. The endovascular coils prevent the extravasation of blood by decreasing the permeability of an aneurysm flow governed by Darcy's law. Here, we developed and explored Pt-coated micro-ropes for potential use as endovascular coils. Electrospinning with subsequent electroplating were employed to fabricate Pt-coated nanofibers, which were tightly twisted to form micro-ropes. The compatibility of Pt micro-ropes with commercial delivery catheters was verified and their performance was experimentally explored in an in vitro experimental model. The developed Pt-coated micro-ropes demonstrated feasibility as efficient and low-cost endovascular coils. STATEMENT OF SIGNIFICANCE: The use of Platinum (Pt)-coated polymer nanofibers to prevent blood extravasation has been demonstrated. These Pt nanofibers were installed within a microfluidic channel, and the resulting reduced permeability was evaluated using a fluid similar to blood. Based on the obtained results, these newly developed nanofibers are expected to decrease the operation cost for aneurysmal subarachnoid hemorrhage (SAH), owing their reduced size and low material cost. Overall, the use of this new material should reduce the operational risk associated with the multiple steps required to place the Pt coils at the SAH site. The compatibility of Pt micro-ropes with commercial delivery catheters was verified and their performance was experimentally explored in an in vitro experimental model. The developed Pt-coated micro-ropes demonstrated feasibility as efficient and low-cost endovascular coils.

A new delivery system based on apple pomace-pectin gels to encourage the viability of antimicrobial strains

This work was aimed to investigate the concept of the valorization of apple processing by-products to produce a new preservation system based on apple pomace gels to encourage the viability of antimicrobial Lactobacillus strains. A high frequency (850 kHz) low power (1.3 W/cm²) ultrasound-stimulated cavitation was used for the structure modulating of gels under low-temperature (50 ℃) conditions. Medium esterified apple pectin was added to apple pomace to improve its texture properties and stability. The monitoring of the process of gelation was performed by using acoustic technique and method, based on the measurement of the distance (parameter h, mm) traveled by a free-falling module. The obtained data were then compared to gel texture measurements. The results suggest that low power ultrasound leads to a reduced jelly mass stickiness and increased gel hardness, compared to the thermally treated sample. The immobilization of probiotic cells in low pectin apple pomace gels did not sufficiently protect the microorganisms. The higher viability of immobilized Lactobacillus paracasei (54-77%) compared to L. plantarum (43-59%) was recorded after incubation at acidic conditions (pH 2.0). The most suitable system for preserving bacterial cells during storage can be the apple pomace-pectin gel containing up to 53% pectin as a stabilizer retaining 84% of viable cells after one-month storage at 4 ℃. The apple pomace-pectin hydrogels with gelation rate (dh/dt) of 0.03-0.05 mm/s can be used for the preservation of bacterial cells as a suitable functional ingredient for food.

Synthesis, characterization and sorption studies of aromatic compounds by hydrogels of chitosan blended with β-cyclodextrin- and PVA-functionalized pectin

Complex coacervation of chitosan with β-cyclodextrin- and poly(vinyl alcohol)-functionalized pectin: ability for simultaneous removal of six different aromatic compounds.

Pectin and charge modified pectin hydrogel beads as a colon-targeted drug delivery carrier

The physical and chemical properties of commercial low methoxyl citrus pectins, CP 28 and CP 55, and a pectinmethylesterase (PME) charge modified citrus pectin (MP 38) were compared, and the differences in ability to encapsulate indomethacin in hydrogel beads was determined at 0.5 or 1.0% (w/v) indomethacin ratio, and 100, 200 or 300 mM CaCl(2) solution. In order to investigate the drug release characteristics, indomethacin loaded dried hydrogel beads were immersed in simulated gastric fluids (pH 1.2) for 2h, followed by immersing in simulated intestinal fluids (pH 7.4) for 3h. Pectin type was highly significant (p<0.0001) for encapsulation efficiency and in vitro release assay. Encapsulation efficiency was also highly affected (p<0.0001) by indomethacin ratio and CaCl(2) concentration. The accumulative release rate of indomethacin from pectin hydrogel bead was less than 15% in simulated gastro-intestinal fluids. MP 38 beads showed significantly higher entrapment efficiency and lower release rate than beads formed from CP 28 or CP 55. MP 38 hydrogel formulated with 300 mM CaCl(2) and 0.5% indomethacin ratio showed the highest entrapment efficiency. These studies suggest that charge modification of pectin improves encapsulation efficiency of drugs for colon targeted drug delivery system through oral administration.