Hydrogel-Based Microneedle as a Drug Delivery System.

The skin is considered the largest and most accessible organ in the human body, and allows the use of noninvasive and efficient strategies for drug administration, such as the transdermal drug delivery system (TDDS). TDDSs are systems or patches, with the ability and purpose to deliver effective and therapeutic doses of drugs through the skin. Regarding the specific interaction between hydrogels (HG) and microneedles (MNs), we seek to find out how this combination would be applied in the context of drug delivery, and we detail some possible advantages of the methods used. Depending on the components belonging to the HG matrix, we can obtain some essential characteristics that make the combination of hydrogels-microneedles (HG-MNs) very advantageous, such as the response to external stimuli, among others. Based on multiple characteristics provided by HGMNs that are depicted in this work, it is possible to obtain unique properties that include controlled, sustained, and localized drug release, as well as the possibility of a synergistic association between the components of the formulation and the combination of more than one bioactive component. In conclusion, a system based on HG-MNs can offer many advantages in the biomedical field, bringing to light a new technological and safe system for improving the pharmacokinetics and pharmacodynamics of drugs and new treatment perspectives.

Delivery Systems in Ocular Retinopathies: The Promising Future of Intravitreal Hydrogels as Sustained-Release Scaffolds.

Slow-release delivery systems are needed to ensure long-term sustained treatments for retinal diseases such as age-related macular degeneration and diabetic retinopathy, which are currently treated with anti-angiogenic agents that require frequent intraocular injections. These can cause serious co-morbidities for the patients and are far from providing the adequate drug/protein release rates and required pharmacokinetics to sustain prolonged efficacy. This review focuses on the use of hydrogels, particularly on temperature-responsive hydrogels as delivery vehicles for the intravitreal injection of retinal therapies, their advantages and disadvantages for intraocular administration, and the current advances in their use to treat retinal diseases.

Rational Design of Hydrogels for Cationic Antimicrobial Peptide Delivery: A Molecular Modeling Approach.

In light of the growing bacterial resistance to antibiotics and in the absence of the development of new antimicrobial agents, numerous antimicrobial delivery systems over the past decades have been developed with the aim to provide new alternatives to the antimicrobial treatment of infections. However, there are few studies that focus on the development of a rational design that is accurate based on a set of theoretical-computational methods that permit the prediction and the understanding of hydrogels regarding their interaction with cationic antimicrobial peptides (cAMPs) as potential sustained and localized delivery nanoplatforms of cAMP. To this aim, we employed docking and Molecular Dynamics simulations (MDs) that allowed us to propose a rational selection of hydrogel candidates based on the propensity to form intermolecular interactions with two types of cAMPs (MP-L and NCP-3a). For the design of the hydrogels, specific building blocks were considered, named monomers (MN), co-monomers (CM), and cross-linkers (CL). These building blocks were ranked by considering the interaction with two peptides (MP-L and NCP-3a) as receptors. The better proposed hydrogel candidates were composed of MN3-CM7-CL1 and MN4-CM5-CL1 termed HG1 and HG2, respectively. The results obtained by MDs show that the biggest differences between the hydrogels are in the CM, where HG2 has two carboxylic acids that allow the forming of greater amounts of hydrogen bonds (HBs) and salt bridges (SBs) with both cAMPs. Therefore, using theoretical-computational methods allowed for the obtaining of the best virtual hydrogel candidates according to affinity with the specific cAMP. In conclusion, this study showed that HG2 is the better candidate for future in vitro or in vivo experiments due to its possible capacity as a depot system and its potential sustained and localized delivery system of cAMP.

Perspectives toward the Development of Advanced Materials Based on Bacterial Polysaccharides.

Bacteria and their enzymatic machinery, also called bacterial cell factories, produce a diverse variety of biopolymers, such as polynucleotides, polypeptides and polysaccharides, with different and fundamental cellular functions. Polysaccharides are the most widely used biopolymers, especially in biotechnology. This type of biopolymer, thanks to its physical and chemical properties, can be used to create a wide range of advanced bio-based materials, hybrid materials and nanocomposites for a variety of exciting biomedical applications. In contrast to synthetic polymers, bacterial polysaccharides have several advantages, such as biocompatibility, biodegradability, low immunogenicity, and non-toxicity, among others. On the other hand, the main advantage of bacterial polysaccharides compared to polymers extracted from other natural sources is that their physicochemical properties, such as purity, porosity, and malleability, among others, can be adapted to a specific application with the use of biotechnological tools and/or chemical modifications. Another great reason for using bacterial polysaccharides is due to the possibility of developing advanced materials from them using bacterial factories that can metabolize raw materials (recycling of industrial and agricultural wastes) that are readily available and in large quantities. Moreover, through this strategy, it is possible to curb environmental pollution. In this article, we project the desire to move towards large-scale production of bacterial polysaccharides taking into account the benefits, weaknesses and prospects in the near future for the development of advanced biological materials for medical and pharmaceutical purposes.

Comparative Study of Three Dyes' Adsorption onto Activated Carbon from Chenopodium quinoa Willd and Quillaja saponaria.

The present study shows porous activated carbon obtained from Chenopodium quinoa Willd and Quillaja saponaria and their use as potential adsorbents to remove three types of dyes from aqueous solutions. The adsorption results were compared with commercial charcoal to check their efficiency. All porous carbon materials were activated using carbon dioxide and steam and fully characterized. Moreover, the steam-activated samples exhibited a high total pore volume with a BET surface area of around 800 m2 g−1. Batch adsorption experiments showed that commercial charcoal is the charcoal that offered the best adsorption efficiency for tartrazine and sunset yellow FCF. However, in the case of crystal violet, all activated carbons obtained from Chenopodium quinoa Willd and Quillaja saponaria showed the best captures, outperforming commercial charcoal. Molecular dockings of the dyes on the commercial charcoal surface were performed using AutoDock Vina. The kinetic results of the three isotherm's models for the present data follow the order: Langmuir~Freundlich > Temkin.

Development of "on-demand" thermo-responsive hydrogels for anti-cancer drugs sustained release: Rational design, in silico prediction and in vitro validation in colon cancer models.

A rational design accurate based on the use of Statistical Design of the Experiments (DoE) and Molecular Dynamics Simulations Studies allows the prediction and the understanding of thermo-responsive hydrogels prepared regarding their gelation temperature and anti-cancer drug release rate. N-isopropylacrilamide (NIPAM) modified with specific co-monomers and crosslinkers, can be used to prepare "on-demand" thermo-responsive hydrogels with the ideal properties for clinical applications in which local sustained release of drugs is crucial. Two preferential formulations resulting from the predictive studies of DoE and In Silico methods were synthesized by radical polymerization, fully characterized, and loaded with the anticancer drug Doxorubicin (Dox). The hydrogel formulations were characterized by swelling rate, turbidity, FTIR, 1H NMR, SEM, gelation time, rheology, and biocompatibility assays. Both formulations demonstrated adequate morphologic, rheological, and biocompatibility properties; however, important differences in terms of drug retention were detected. As demonstrated by a Dox cumulative release study and posteriorly confirmed by an efficacy assay in an in vitro colorectal cancer model, the formulation composed by NIPAM and 4-penten-1-ol crosslinked with poly(ethylene glycol) diacrylate (PEGDA) (PNiPenPH) present a slow release over the time, presenting ideal properties to become and ideal depot system for the local sustained release of anticancer drugs as adjuvant therapy or in the case of non-resectable tumors.

Use of Poly(vinyl alcohol)-Malic Acid (CLHPMA) Hydrogels and Chitosan Coated Calcium Alginate (CCCA) Microparticles as Potential Sorbent Phases for the Extraction and Quantitative Determination of Pesticides from Aqueous Solutions.

Pesticides are used worldwide to increase crop yields in agriculture. However, their toxicity and accumulation capacity can make them toxic to the environment, animals and humans. In the case of workers chronically exposed to these substances, they must be sampled continuously, so urine is an excellent option. In this sense, this study proposes to use poly(vinyl alcohol)-malic acid hydrogels, and chitosan-coated calcium alginate as new sorbent phases to be used in pesticide determination processes in urine. To better understand the behavior of these materials in the capture and desorption process, molecular dynamics simulations (MDS) were used, and desorption experiments were performed, using mechanical agitation, ultrasound, and pH variation in the desorption process, in order to optimize the parameters to obtain better recoveries. Under the optimal experimental conditions, the maximum recoveries were of the order of 11% (CFN), 3% (KCF), 53% (DMT), 18% (MTD) and 35% (MTL). Although the recoveries were not exhaustive, they are a first approximation for the use of these new sorbent phases in the determination of this type of compound in aqueous solutions and urine.

Sustained Release of Linezolid from Prepared Hydrogels with Polyvinyl Alcohol and Aliphatic Dicarboxylic Acids of Variable Chain Lengths.

A series of hydrogels with a specific release profile of linezolid was successfully synthesized. The hydrogels were synthesized by cross-linking polyvinyl alcohol (PVA) and aliphatic dicarboxylic acids, which include succinic acid (SA), glutaric acid (GA), and adipic acid (AA). The three crosslinked hydrogels were prepared by esterification and characterized by equilibrium swelling ratio, infrared spectroscopy, thermogravimetric analysis, mechanical properties, and scanning electron microscopy. The release kinetics studies of the linezolid from prepared hydrogels were investigated by cumulative drug release and quantified by chromatographic techniques. Mathematical models were carried out to understand the behavior of the linezolid release. These data revealed that the sustained release of linezolid depends on the aliphatic dicarboxylic acid chain length, their polarity, as well as the hydrogel crosslinking degree and mechanical properties. The in vitro antibacterial assay of hydrogel formulations was assessed in an Enterococcus faecium bacterial strain, showing a significant activity over time. The antibacterial results were consistent with cumulative release assays. Thus, these results demonstrated that the aliphatic dicarboxylic acids used as crosslinkers in the PVA hydrogels were a determining factor in the antibiotic release profile.

Data of preparation and evaluation of supramolecular hydrogel based on cellulose for sustained release of therapeutic substances with antimicrobial and wound healing properties.

The data article refers to the paper "supramolecular hydrogel based on cellulose for sustained release of therapeutic substances with antimicrobial and wound healing properties"[1]. The dataset includes the synthesis and characterization of (E)-1,3-bis(4-(allyloxy)phenyl)prop­2-en-1-one (3) (crosslinking agent). Moreover, the multiwall carbon nanotubes (MWCNTs) synthesis and functionalization (MWCNTs-COOH) are described. The formulation obtained by adding multiwalled carbon nanotubes-COOH with the crosslinked cellulose-chalcone hydrogel is abbreviated as MWCNTsCCH, and the same formulation loaded with therapeutic substances (TS) is named MWCNTsCCH-TS. The MWCNTsCCH database such as components and their amounts, swelling degree, thermogravimetric analysis, and cytotoxicity evaluation are depicted. Finally, to elucidate the mechanism of therapeutic substances release, the obtained averages of the release profiles were fitted through mathematical models.

Supramolecular hydrogels based on cellulose for sustained release of therapeutic substances with antimicrobial and wound healing properties.

A multifaceted hydrogel-based formulation was reported. The hydrogel was prepared by crosslinking cellulose and substituted chalcone. Moreover, the formulation was conjugated with carbon nanotubes with the aim of increasing the loading amount of bioactive compounds such as allantoin, dexpanthenol, resveratrol and linezolid. The hydrogel formation was confirmed by swelling tests, FT-IR spectroscopy, thermogravimetric analysis and SEM. The hydrogel showed an improved release rate of therapeutic substances, exhibiting a simultaneous and coordinated release according to the chromatographic studies. The efficacy of drug release was confirmed by wound closure and in vivo wound healing studies that showed promising healing results. The antibacterial assays demonstrated that the sustained release of linezolid tends to be very effective. In conclusion, a multifaceted formulation based on carbon nanotube-containing cellulose-chalcone was developed that can potentially be utilized in treating complex wounds owing to its improved wound healing properties and prevention of potential infections.

Comparison of the Oxidative Stability and Antioxidant Activity of Extra-Virgin Olive Oil and Oils Extracted from Seeds of Colliguaya integerrima and Cynara cardunculus Under Normal Conditions and After Thermal Treatment.

We investigated the potential of two oil extracts from seeds of Colliguaya integerrima (CIO) and Cynara cardunculus (CO) to use as nutritionally edible oils. For this purpose, oil quality was accessed by determining the fatty acid composition, peroxide value, acid value, iodine value, saponification number, phenolic contents, and oxidative stability during thermally induced oxidation of CIO and CO oils and compared to those of extra-virgin olive oil (EVOO). The chemical composition results demonstrated that both oils could be nutritional sources of essential unsaturated fatty acids. Moreover, according to the gravimetric analysis, the main decomposition step occurred in the temperature range of 200-420 °C, showing a similar thermal behavior of EVOO oil. However, CO and EVOO oils showed a higher phenolic content at degradation onset temperature (T0) in contrast with CIO oil. The antioxidant activity of the different studied oils showed a direct correlation with the phenol contents, up to temperatures around 180 °C, where the percentage of free radical scavenging assay for EVOO was higher than CO in contrast with the TPC values. Finally, we analyzed the minor components before and after heating CIO and CO at 180 °C by gas chromatography-mass spectrometry (GC-MS) using library search programs.

Film Dressings Based on Hydrogels: Simultaneous and Sustained-Release of Bioactive Compounds with Wound Healing Properties.

This research proposes the rational modeling, synthesis and evaluation of film dressing hydrogels based on polyvinyl alcohol crosslinked with 20 different kinds of dicarboxylic acids. These formulations would allow the sustained release of simultaneous bioactive compounds including allantoin, resveratrol, dexpanthenol and caffeic acid as a multi-target therapy in wound healing. Interaction energy calculations and molecular dynamics simulation studies allowed evaluating the intermolecular affinity of the above bioactive compounds by hydrogels crosslinked with the different dicarboxylic acids. According to the computational results, the hydrogels crosslinked with succinic, aspartic, maleic and malic acids were selected as the best candidates to be synthesized and evaluated experimentally. These four crosslinked hydrogels were prepared and characterized by FTIR, mechanical properties, SEM and equilibrium swelling ratio. The sustained release of the bioactive compounds from the film dressing was investigated in vitro and in vivo. The in vitro results indicate a good release profile for all four analyzed bioactive compounds. More importantly, in vivo experiments suggest that prepared formulations could considerably accelerate the healing rate of artificial wounds in rats. The histological studies show that these formulations help to successfully reconstruct and thicken epidermis during 14 days of wound healing. Moreover, the four film dressings developed and exhibited excellent biocompatibility. In conclusion, the novel film dressings based on hydrogels rationally designed with combinatorial and sustained release therapy could have significant promise as dressing materials for skin wound healing.

Preparation of Hydrogel/Silver Nanohybrids Mediated by Tunable-Size Silver Nanoparticles for Potential Antibacterial Applications.

In this study, a versatile synthesis of silver nanoparticles of well-defined size by using hydrogels as a template and stabilizer of nanoparticle size is reported. The prepared hydrogels are based on polyvinyl alcohol and maleic acid as crosslinker agents. Three hydrogels with the same nature were synthesized, however, the crosslinking degree was varied. The silver nanoparticles were synthesized into each prepared hydrogel matrix achieving three significant, different-sized nanoparticles that were spherical in shape with a narrow size distribution. It is likely that the polymer network stabilized the nanoparticles. It was determined that the hydrogel network structure can control the size and shape of the nanoparticles. The hydrogel/silver nanohybrids were characterized by swelling degree, Thermal Gravimetric Analysis (TGA), Fourier Transform Infrared (FT-IR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscope (TEM). Antibacterial activity against Staphylococcus aureus was evaluated, confirming antimicrobial action of the encapsulated silver nanoparticles into the hydrogels.

Polymeric substances for the removal of ochratoxin A from red wine followed by computational modeling of the complexes formed.

Ochratoxin A (OTA) is a mycotoxin produced by filamentous-type fungi that contaminates a wide variety of foods and beverages such as wines. In these trials, we evaluated the capacity of the following polymers for the removal of OTA from acidic model solutions and red wine: polyvinylpolypyrrolidone (PVPP), resin of N-vinyl-2-pyrrolidinone with ethylene glycol dimethacrylate and triallyl isocyanurate (PVP-DEGMA-TAIC), and poly(acrylamide-co-ethylene glycol-dimethacrylate) (PA-EGDMA). In acidic model solution, PVP-DEGMA-TAIC and PA-EGDMA polymers removed up to 99.9% of OTA, but their trapping capacity was highly reduced by the presence of competing phenolic substances (i.e. gallic acid and 4-methylcathecol). In real red wine, PA-EGDMA polymer showed the most promising results, with more than 68.0% OTA removal and less than 14.0% reduction in total phenolic. Finally, computational chemistry analyses showed that the affinity between OTA and the polymers studied would be due to Van der Waals interactions.

Rational Design, Synthesis and Evaluation of γ-CD-Containing Cross-Linked Polyvinyl Alcohol Hydrogel as a Prednisone Delivery Platform.

This study describes the in-silico rational design, synthesis and evaluation of cross-linked polyvinyl alcohol hydrogels containing γ-cyclodextrin (γ-CDHSAs) as platforms for the sustained release of prednisone (PDN). Through in-silico studies using semi-empirical quantum mechanical calculations, the effectiveness of 20 dicarboxylic acids to generate a specific cross-linked hydrogel capable of supporting different amounts of γ-cyclodextrin (γ-CD) was evaluated. According to the interaction energies calculated with the in-silico studies, the hydrogel made from PVA cross-linked with succinic acids (SA) was shown to be the best candidate for containing γ-CD. Later, molecular dynamics simulation studies were performed in order to evaluate the intermolecular interactions between PDN and three cross-linked hydrogel formulations with different proportions of γ-CD (2.44%, 4.76% and 9.1%). These three cross-linked hydrogels were synthesized and characterized. The loading and the subsequent release of PDN from the hydrogels were investigated. The in-silico and experimental results showed that the interaction between PDN and γ-CDHSA was mainly produced with the γ-CDs linked to the hydrogels. Thus, the unique structures and properties of γ-CDHSA demonstrated an interesting multiphasic profile that could be utilized as a promising drug carrier for controlled, sustained and localized release of PDN.

In-Silico Design, Synthesis and Evaluation of a Nanostructured Hydrogel as a Dimethoate Removal Agent.

This study describes the in-silico design, synthesis, and evaluation of a cross-linked PVA hydrogel (CLPH) for the absorption of organophosphorus pesticide dimethoate from aqueous solutions. The crosslinking effectiveness of 14 dicarboxilic acids was evaluated through in-silico studies using semiempirical quantum mechanical calculations. According to the theoretical studies, the nanopore of PVA cross-linked with malic acid (CLPH-MA) showed the best interaction energy with dimethoate. Later, using all-atom molecular dynamics simulations, three hydrogels with different proportions of PVA:MA (10:2, 10:4, and 10:6) were used to evaluate their interactions with dimethoate. These results showed that the suitable crosslinking degree for improving the affinity for the pesticide was with 20% (W%) of the cross-linker. In the experimental absorption study, the synthesized CLPH-MA20 recovered 100% of dimethoate from aqueous solutions. Therefore, the theoretical data were correlated with the experimental studies. Surface morphology of CLPH-MA20 by Scanning Electron Microscopy (SEM) was analyzed. In conclusion, the ability of CLPH-MA20 to remove dimethoate could be used as a technological alternative for the treatment of contaminated water.

Selective and Efficient Arsenic Recovery from Water through Quaternary Amino-Functionalized Silica.

The free-radical graft polymerization of acryloxyethyl-trimethylammonium chloride onto commercial silica particles was studied experimentally for extraction of arsenic ions from water. Two steps were used to graft acryloxyethyl-trimethylammonium chloride (Q) onto the surface of nanosilica: anchoring vinyltrimethoxysilane (VTMSO) onto the surface of silica to modify it with double bonds and then grafting Q onto the surface of silica with potassium persulfate as an initiator. The products were characterized by Fourier-transform infrared (FT-IR), the thermogravimetric analysis (TGA), scanning electron microscopy (SEM), 13C, 29Si nuclear magnetic resonance (NMR), and X-ray powder diffraction (XRD). The results showed that it is easy to graft Q onto the surface of silica under radical polimerization. The morphology analysis of silica and modified silica indicated that the silica decreased the size scale after modification. Q/VTMSO-SiO2 was tested for its ability to remove arsenic from drinking water. The results show that the new silica hybrid particles efficiently remove all arsenate ions. In addition, Q/VTMSO-SiO2 showed better sorption capacities for other metal ions (such as copper, zinc, chromium, uranium, vanadium, and lead) than a commercial water filter.

Rational Development of a Novel Hydrogel as a pH-Sensitive Controlled Release System for Nifedipine.

This work depicts the rational development (in-silico design, synthesis, characterization and in-vitro evaluation) of polyvinyl alcohol hydrogels (PVAH) cross-linked with maleic acid (MA) and linked to γ-cyclodextrin molecules (γ-CDPVAHMA) as systems for the controlled and sustained release of nifedipine (NFD). Through computational studies, the structural blocks (PVA chain + dicarboxylic acid + γ-CD) of 20 different hydrogels were evaluated to test their interaction energies (ΔE) with NFD. According to the ΔE obtained, the hydrogel cross-linked with maleic acid was selected. To characterize the intermolecular interactions between NFD and γ-CDPVAHMA, molecular dynamics simulation studies were carried out. Experimentally, three hydrogel formulations with different proportions of γ-CD (2.43%, 3.61% and 4.76%) were synthesized and characterized. Both loading and release of NFD from the hydrogels were evaluated at acid and basic pH. The computational and experimental results show that γ-CDs linked to the hydrogels were able to form 1:1 inclusion complexes with NFD molecules. Finally, γ-CDPVAHMA-3 demonstrated to be the best pH-sensitive release platform for nifedipine. Its effectiveness could significantly reduce the adverse effects caused by the anticipated release of NFD in the stomach of patients.

A review on pesticide removal through different processes.

The main organic pollutants worldwide are pesticides, persistent chemicals that are of concern owing to their prevalence in various ecosystems. In nature, pesticide remainders are subjected to the chemical, physical, and biochemical degradation process, but because of its elevated stability and some cases water solubility, the pesticide residues persist in the ecosystem. The removal of pesticides has been performed through several techniques classified under biological, chemical, physical, and physicochemical process of remediation from different types of matrices, such as water and soil. This review provides a description of older and newer techniques and materials developed to remove specific pesticides according to previous classification, which range from bioremediation with microorganisms, clay, activated carbon, and polymer materials to chemical treatment based on oxidation processes. Some types of pesticides that have been removed successfully to large and small scale include, organophosphorus, carbamates, organochlorines, chlorophenols, and synthetic pyrethroids, among others. The most important characteristics, advantages, and disadvantages of techniques and materials for removing pesticides are described in this work.