Thermosensitive hydrogels of poly(methyl vinyl ether-co-maleic anhydride) - Pluronic(®) F127 copolymers for controlled protein release

ISX9 loaded thermoresponsive nanoparticles for hair follicle regrowth

There is a high demand for an optimal drug delivery system to treat androgenetic alopecia. Topical application of ISX9, which is a neurogenesis inducer, has been found to stimulate hair follicle (HF) regrowth by upregulating the Wnt/β-catenin signaling pathway, an essential pathway involved in initiating HF growth and development. In the present study, a temperature-sensitive, biopolymer-based, biocompatible, and eco-friendly drug-delivery system was synthesized. This system comprised chitosan-grafted poly(glycidyl methacrylate-co-N-isopropyl acrylamide) (Poly(GMA-co-NIPAAm)@CS-PGNCS) as the shell component and PF127 as the core polymer. The hydrophobic nature of the PF127 block copolymer efficiently dissolved the partially water-soluble drug, ISX9, and the thermos-responsive shell polymer effectively released the drug at a definite skin temperature. The optimized spherical nanoparticles demonstrated the lowest critical solution temperature (LCST) at 32 ± 2 °C with a diameter of 100-250 nm, which delivered encapsulated ISX9 with greater precision than topical ISX9. In a series of in vivo experiments, we demonstrated that ISX9-coated TBNPs upregulated the expression of β-catenin, active β-catenin, Wnt target genes, stemness marker genes, proliferating cell nuclear antigen, HF stem cell markers, and HF markers including VEGF, TGF, and IGF-1 more effectively than topical ISX9. These results suggest that TBNPs could be employed as a platform for effective transdermal delivery of various hydrophobic drugs.

Temperature-Responsive Hydrogel for Silver Sulfadiazine Drug Delivery: Optimized Design and In Vitro/In Vivo Evaluation

Response surface methodology (RSM) was applied to optimise a temperature-responsive hydrogel formulation synthesised via the direct incorporation of biocellulose, which was extracted from oil palm empty fruit bunches (OPEFB) using the PF127 method. The optimised temperature-responsive hydrogel formulation was found to contain 3.000 w/v% biocellulose percentage and 19.047 w/v% PF127 percentage. The optimised temperature-responsive hydrogel provided excellent LCST near to the human body surface temperature, with high mechanical strength, drug release duration, and inhibition zone diameter against Staphylococcus aureus. Moreover, in vitro cytotoxicity testing against human epidermal keratinocyte (HaCaT) cells was conducted to evaluate the toxicity of the optimised formula. It was found that silver sulfadiazine (SSD)-loaded temperature-responsive hydrogel can be used as a safe replacement for the commercial SSD cream with no toxic effect on HaCaT cells. Last, but not least, in vivo (animal) dermal testing-both dermal sensitization and animal irritation-were conducted to evaluate the safety and biocompatibility of the optimised formula. No sensitization effects were detected on the skin applied with SSD-loaded temperature-responsive hydrogel indicating no irritant response for topical application. Therefore, the temperature-responsive hydrogel produced from OPEFB is ready for the next stage of commercialisation.

Pluronic® F127 Hydrogel Containing Silver Nanoparticles in Skin Burn Regeneration: An Experimental Approach from Fundamental to Translational Research

Presently, skin burns are considered one of the main public health problems and lack therapeutic options. In recent years, silver nanoparticles (AgNPs) have been widely studied, playing an increasingly important role in wound healing due to their antibacterial activity. This work is focused on the production and characterization of AgNPs loaded in a Pluronic® F127 hydrogel, as well as assessing its antimicrobial and wound-healing potential. Pluronic® F127 has been extensively explored for therapeutic applications mainly due to its appealing properties. The developed AgNPs had an average size of 48.04 ± 14.87 nm (when prepared by method C) and a negative surface charge. Macroscopically, the AgNPs solution presented a translucent yellow coloration with a characteristic absorption peak at 407 nm. Microscopically, the AgNPs presented a multiform morphology with small sizes (~50 nm). Skin permeation studies revealed that no AgNPs permeated the skin after 24 h. AgNPs further demonstrated antimicrobial activity against different bacterial species predominant in burns. A chemical burn model was developed to perform preliminary in vivo assays and the results showed that the performance of the developed AgNPs loaded in hydrogel, with smaller silver dose, was comparable with a commercial silver cream using higher doses. In conclusion, hydrogel-loaded AgNPs is potentially an important resource in the treatment of skin burns due to their proven efficacy by topical administration.

Design as strategy for evaluation of the mechanical properties of binary mixtures composed of poly(methyl vinyl ether-alt-maleic anhydride) and Pluronic F127 for biomedical applications

The synergism between thermoresponsive and bioadhesive polymers can lead to the optimization of materials with enhanced mechanical and bioadhesive properties. Quality by Design can assure the understanding and control of formulation variables. In this approach, Design of Experiment has been widely utilized as an important strategy. Poly(methyl vinyl ether-alt-maleic anhydride) (PVMMA) is a bioadhesive polymer and Pluronic F127 (PF127) shows thermoresponsiveness. The association of these two polymers has been poorly investigated. The aim of this work was to study the mechanical, bioadhesive and rheological properties of polymer mixtures composed of PVMMA and PF127, in order to select the best conditions and formulations for biomedical applications. Textural properties (hardness, compressibility, adhesiveness, cohesiveness and elasticity), softness index, bioadhesion and rheological characteristics (flow and viscoelasticity) showed that 17.5-20% (w/w) PF127-polymer mixtures displayed improved values of the parameters. However, the rheological interaction parameter showed low synergism, due to the polymers' characteristics and system organization. The formulations displayed gelation temperatures suitable for administration, with improved bioadhesive properties mainly at 34 °C and suggests the formulations can be used for biomedical applications. DoE constituted an important tool to investigate these systems showing the main effects that significantly influence the binary mixtures.

Bioadhesive poly(methyl vinyl ether-co-maleic anhydride)-TPGS copolymer modified PLGA/lipid hybrid nanoparticles for improving intestinal absorption of cabazitaxel

A bioadhesive nanocarrier, PTNP, was constructed by utilizing a novel poly(methyl vinyl ether-co-maleic anhydride)- D-α-Tocopheryl polyethylene glycol succinate (PVMMA-TPGS) copolymer in the PLGA/lipid hybrid nanoparticles (PLGA NPs) for improving oral delivery of cabazitaxel (CTX). The PVMMA-TPGS was synthesized by the ring-opening polymerization of the anhydride groups with the hydroxyl groups, combining the bioadhesive property of PVMMA with P-glycoprotein (P-gp) inhibitory effect of TPGS. The CTX-loaded PTNPs (CTX-PTNPs) were prepared by an emulsification-solvent evaporation method and performed a spherical appearance with a uniform particle size of 192.2 nm. The CTX-PTNPs were surface negatively charged, and exhibited good drug loading (10.2%) and encapsulation efficiency (92.1%). A sustained drug release and high stability in simulated gastrointestinal environment were confirmed in in vitro studies. The in vitro mucin adhesion and in vivo intestinal retention experiments indicated that the PTNPs had a stronger bioadhesive effect and a notably longer intestinal retention than the control PLGA NPs, due to the interaction of PVMMA on the PTNP surface with the intestinal mucosa. Moreover, an enhanced intestinal permeability of the PTNPs was also verified in in vivo and ex vivo intestinal permeation studies, which was probably attributed to the extended retention of PTNPs in intestinal mucosa and the P-gp inhibitory effect of TPGS. As respected, in in vivo pharmacokinetic study, the T_max and oral bioavailability of CTX were dramatically improved to 1.08 h and 28.84% by the PTNPs, respectively, obviously superior to the CTX solution and the PLGA NPs, further demonstrating the high-efficiency in oral delivery of CTX. Hence, this bioadhesive carrier is proposed to be a potential and promising strategy for increasing oral absorption of small molecule insoluble drugs.

Advances in the therapeutic delivery and applications of functionalized Pluronics: A critical review

Pluronic (PEO-PPO-PEO) block copolymers can form nano-sized micelles with a structure composed of a hydrophobic PPO core and hydrophilic PEO shell layer. Pluronics are U.S. Food and Drug Administration approved polymers, which are widely used for solubilization of drugs and their delivery, gene/therapeutic delivery, diagnostics, and tissue engineering applications due to their non-ionic properties, non-toxicity, micelle forming ability, excellent biocompatibility and biodegradability. Although Pluronics have been employed as drug carrier systems for several decades, numerous issues such as rapid dissolution, shorter residence time in biological media, fast clearance and weak mechanical strength have hindered their efficacy. Pluronics have been functionalized with pH-sensitive, biological-responsive moieties, antibodies, aptamers, folic acid, drugs, different nanoparticles, and photo/thermo-responsive hydrogels. These functionalization strategies enable Pluronics to act as stimuli responsive and targeted drug delivery vehicles. Moreover, Pluronics have emerged in nano-emulsion formulations and have been utilized to improve the properties of cubosomes, dendrimers and nano-sheets, including their biocompatibility and aqueous solubility. Functionalization of Pluronics results in the significant improvement of target specificity, loading capacity, biocompatibility of nanoparticles and stimuli responsive hydrogels for the promising delivery of a range of drugs. Therefore, this review presents an overview of all advancements (from the last 15 years) in functionalized Pluronics, providing a valuable tool for industry and academia in order to optimize their use in drug or therapeutic delivery, in addition to several other biomedical applications.

Development and validation of a high-performance liquid chromatography method for levothyroxine sodium quantification in plasma for pre-clinical evaluation of long-acting drug delivery systems

Levothyroxine (LEVO) sodium is an FDA-approved drug that is used to treat underactive thyroid (hypothyroidism) and other conditions. It is generally used as a thyroid-stimulating hormone administered orally. However, this approach has some drawbacks such as this drug should be taken every day 30 min to 1 h prior to breakfast with an empty stomach, moreover, some food interactions must be monitored. Thus, alternative innovative approaches capable of providing sustained LEVO release should be developed. Our research was designed to establish a simple quantitative determination method for LEVO in rat plasma for pre-clinical evaluation of long acting formulations using a high-performance liquid chromatography method, to validate the analytical method according to ICH guidelines and to characterise its pharmacokinetic behavior in rats. After simple protein precipitation with acetonitrile, LEVO was eluted on a Xselect CSH™ C18 column (Waters, 3.0 × 150 mm) with a particle size of 3.5 μm using a mobile phase of water and acetonitrile at a ratio of 65 : 35% v/v, including 0.1% v/v of trifluoracetic acid. The calibration standards used for plasma ranged between 0.5-1000 ng mL^-1 with a correlation coefficient (r²) of ≥0.998. The limit of detection was 0.44 ng mL^-1 and the lower limit of quantitation was 1.33 ng mL^-1. The extraction recovery of LEVO in rat plasma samples by this method was between 80 and 85%. The method was selective, sensitive, accurate and precise for detecting and quantifying LEVO in a pharmacokinetic study carried out in rats for pre-clinical evaluation of long acting formulations. The validated HPLC method meets the ICH established requirements and therefore offers a wide range of potential applications in pre-clinical therapeutic drug monitoring, pharmacokinetics and toxicology.

Polymeric-based drug delivery systems for veterinary use: State of the art

One of the challenges to the success of veterinary pharmacotherapy is the limited number of drugs and dosage forms available exclusively to this market, due to the interspecies variability of animals, such as anatomy, physiology, pharmacokinetics, and pharmacodynamics. For this reason, studies in this area have become a highlight, since they are still scarce in comparison with those on human drug use. To overcome many limitations related to the bioavailability, efficacy, and safety of pharmacotherapy in animals, especially livestock and domestic animals, polymers-based drug delivery systems are promising tools if they guarantee greater selectivity and less toxicity in dosage forms. In addition, these tools may be developed according to the great interspecies variability. To contribute to these discussions, this paper provides an updated review of the major polymer-based drug delivery systems projected for veterinary use. Traditional and innovative drug delivery systems based on polymers are presented, with an emphasis on films, microparticles, micelles, nanogels, nanoparticles, tablets, implants and hydrogel-based drug delivery systems. We discuss important concepts for the veterinarian about the mechanisms of drug release and, for the pharmacist, the advantages in the development of pharmaceutical forms for the animal population. Finally, challenges and opportunities are presented in the field of pharmaceutical dosage forms for veterinary use in response to the interests of the pharmaceutical industry.

Design of novel orotransmucosal vaccine-delivery platforms using artificial intelligence

The linings of the oral cavity are excellent needle-free vaccination sites, able to induce immune responses at distal sites and confer systemic protection. However, owing to the mucosal tissues' intrinsic characteristics, the design of effective antigen-delivery systems is not an easy task. In the present work, we propose to develop and characterize thermosensitive and mucoadhesive hydrogels for orotransmucosal vaccination taking advantage of artificial intelligence tools (AIT). Hydrogels of variable composition were obtained combining Pluronic® F127 (PF127), Hybrane® S1200 (HS1200) and Gantrez® AN119 (AN119) or S97 (S97). Systems were characterized in terms of physicochemical properties, adhesion capacity to mucosal tissues and antigen-like microspheres release. Additionally, polymers biocompatibility and their immune-stimulation capacity was assessed in human macrophages. Interestingly, cells treated with HS1200 exhibited a significant proliferation enhancement compared to control. The use of AIT allowed to determine the effect of each polymer on formulations properties. The proportions of PF127 and Gantrez® are mainly the factors controlling gelation temperature, mucoadhesion, adhesion work and gel strength. Meanwhile, cohesion and short-term microsphere release are dependent on the PF127 concentration. However, long-term microsphere release varies depending on the Gantrez® variety and the PF127 concentration used. Hydrogels prepared with S97 showed slower microsphere release. The use of AIT allowed to establish the conditions able to produce ternary hydrogels with immune-stimulatory properties together with adequate mucoadhesion capacity and antigen-like microspheres release.

A difunctional Pluronic®127-based in situ formed injectable thermogels as prolonged and controlled curcumin depot, fabrication, in vitro characterization and in vivo safety evaluation

Curcumin has been reported to be used widely against many types of pathological conditions in clinics. However, due to its limitations such as poor solubility, poor oral absorption and low stability have limited its applications. In the current study, a series of novel chemically cross-linkable depot gel formulations were developed based on thermoresponsive micellar polymer (Pluronic^®127) with polyelectrolyte hydrophilic monomer, that is, 2-acrylamido-2-methylpropane sulfonic acid by cold and in situ grafting polymerization method. The formulations were aimed to deliver curcumin at controlled rate from in situ formed depot after administration through subcutaneous route in vivo. The sol-gel phase transitions of formulations were observed by rheological analysis, tube titling and optical transmittance measurements. Maximum swelling of gel formulations was observed at pH 7.4 and below CGT, that is, 25 °C. The in vitro release profile exhibits maximum drug release at pH 7.4 and 25 °C owing to relaxed gel state. In vitro degradation profile of gel formulations showed controlled degradation rate. Cell growth inhibition study confirmed the biocompatibility and safe nature of bare gel formulations against L929 cell lines. In vitro cytotoxic study showed that curcumin loaded in gel formulation has controlled pharmacological activity against HeLa and MCF-7 cancer cells as compared to free drug solution. The IC₅₀ values calculated for pure curcumin solution (30 ± 0.77 µg/ml for HeLa and 27 ± 0.39 µg/ml for MCF-7) were found higher in comparison to curcumin-loaded thermogels against HeLa (19 ± 0.28 µg/ml and 23 ± 0.81 µg/ml) and MCF-7 (22 ± 0.54 µg/ml and 21 ± 0.49 µg/ml). Histopathological and hematological analysis showed the biocompatible nature of hydrogels. Structural confirmation was done by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance spectroscopy (¹H NMR). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) confirmed the thermal stability of the gel formulation. The porous structure of gel formulations was assessed by scanning electron microscopic (SEM) analysis. Results concluded that newly developed gel formulations have thermoresponsive behavior with phase transition at body temperature and can be used as in situ controlled drug depot.

Recent advances in hydrogels as strategy for drug delivery intended to vaginal infections

Vaginal infections represent a clear women health problem due to the several issues as high recurrence rate, drug resistence and emergence of persistent strains. However, achieving improvements in therapeutic efficacy by using conventional formulations intended to vaginal drug delivery remains as a challenge due to anatomy and physiology of the vagina, since the secretion and renewal of vaginal fluids contribute to the removal of the dosage form. Hydrogels have been widely exploited aiming to achieve drug delivery directly into vaginal mucosa for local therapy due to their attractive features as increased residence time of the drug at the action site and control of drug release rates. Some polymers can aggregate specific properties to hydrogels as mucoadhesive, stimuli-responsive and antimicrobial, improving their interaction with the biological interface and therapeutic response. In this review, we highlight the advances, advantages and challenges of the hydrogels as drug and/or nanocarrier vehicles intended to the treatment of vaginal infections, emphasizing also the polymers and their properties more explored on the design these systems to improve the therapeutic effect on the vaginal tissue. In addition, this review can contribute for better exploitation these systems in search of new local treatments for bacterial vaginosis, candidiasis and trichomoniasis.

Intranasal delivery system of bacterial antigen using thermosensitive hydrogels based on a Pluronic-Gantrez conjugate

Thermosensitive hydrogels have been studied as feasible needle-avoidance alternative to vaccine delivery. In this work, we report the development of a new thermal-sensitive hydrogel for intranasal vaccine delivery. This delivery system was formulated with a combination of the polymer Gantrez® AN119 and the surfactant Pluronic® F127 (PF127), with a high biocompatibility, biodegradability and immunoadjuvant properties. Shigella flexneri outer membrane vesicles were used as the antigen model. A stable and easy-to-produce thermosensitive hydrogel which allowed the incorporation of the OMV-antigenic complex was successfully synthetized. A rapid gel formation was achieved at body temperature, which prolonged the OMV-antigens residence time in the nasal cavity of BALB/c mice when compared to intranasal delivery of free-OMVs. In addition, the bacterial antigens showed a fast release profile from the hydrogel in vitro, with a peak at 30 min of incubation at 37 °C. Hydrogels appeared to be non-cytotoxic in the human epithelial HeLa cell line and nose epithelium as well, as indicated by the absence of histopathological features. Immunohistochemical studies revealed that after intranasal administration the OMVs reached the nasal associated lymphoid tissue. These results support the use of here described thermosensitive hydrogels as a potential platform for intranasal vaccination.

Evaluation of microneedles-assisted in situ depot forming poloxamer gels for sustained transdermal drug delivery

In this study, for the first time, we have reported a sustained transdermal drug delivery from thermoresponsive poloxamer depots formed within the skin micropores following microneedle (MN) application. Firstly, we have investigated the sol–gel phase transition characteristics of poloxamers (PF®127, P108, and P87) at physiological conditions. Rheological measurements were evaluated to confirm the critical gelation temperature (CGT) of the poloxamer formulations with or without fluorescein sodium (FS), as a model drug, at various concentrations. Optimized poloxamer formulations were subjected to in vitro release studies using a vial method. Secondly, polymeric MNs were fabricated using laser-engineered silicone micromolds from various biocompatible polymeric blends of Gantrez S-97, PEG 10000, PEG200, PVP K32, and PVP K90. The MN arrays were characterized for mechanical strength, insertion force determination, in situ dissolution kinetics, moisture content, and penetration depth. The optimized MN arrays with good mechanical strength and non-soluble nature were used to create micropores in the neonatal porcine skin. Microporation in neonatal porcine skin was confirmed by dye-binding study, skin integrity assessment, and histology study. Finally, the in vitro delivery of FS from optimized poloxamer formulations was conducted across non-porated vs microporated skin samples using vertical Franz diffusion cells. Results concluded that permeation of FS was sustained for 96 h across the MN-treated skin samples containing in situ forming depot poloxamer formulations compared to non-microporated skin which sustained the FS delivery for 72 h. Confocal microscopic images confirmed the distribution of higher florescence intensity of FS in skin tissues after permeation study in case of MN-treated skin samples vs intact skin samples.

Thermoresponsive gating membranes embedded with liquid crystal(s) for pulsatile transdermal drug delivery: An overview and perspectives

Due to the circadian rhythm regulation of almost every biological process in the human body, physiological and biochemical conditions vary considerably over the course of a 24-h period. Thus, optimal drug delivery and therapy should be effectively controlled to achieve the desired therapeutic plasma concentrations and therapeutic drug responses at the required time according to chronopharmacological concepts, rather than continuous maintenance of constant drug concentrations for an extended time period. For many drugs, it is not always necessary to constantly deliver a drug into the human body under disease conditions due to rhythmic variations. Pulsatile drug delivery systems (PDDSs) have been receiving more attention in pharmaceutical development by providing a predetermined lag period, followed by a fast or rate-controlled drug release after application. PDDSs are characterized by a programmed drug release, which may release a drug at repeatable pulses to match the biological and clinical needs of a given disease therapy. This review article focuses on thermoresponsive gating membranes embedded with liquid crystals (LCs) for transdermal drug delivery using PDDS technology. In addition, the principal rationale and the advanced approaches for the use of PDDSs, the marketed products of chronotherapeutic DDSs with pulsatile function designed by various PDDS technologies, pulsatile drug delivery designed with thermoresponsive polymers, challenges and opportunities of transdermal drug delivery, and novel approaches of LC systems for drug delivery are reviewed and discussed. A brief overview of all academic research articles concerning single LC- or binary LC-embedded thermoresponsive membranes with a switchable on-off permeation function through topical application by an external temperature control, which may modulate the dosing interval and administration time according to the therapeutic needs of the human body, is also compiled and presented. In the near future, since thermal-based approaches have become a well-accepted method to enhance transdermal delivery of different water-soluble drugs and macromolecules, a combination of the thermal-assisted approach with thermoresponsive LCs membranes will have the potential to improve PDDS applications but still poses a great challenge.

Injectable Hydrogels for Cancer Therapy over the Last Decade

The interest in injectable hydrogels for cancer treatment has been significantly growing over the last decade, due to the availability of a wide range of starting polymer structures with tailored features and high chemical versatility. Many research groups are working on the development of highly engineered injectable delivery vehicle systems suitable for combined chemo-and radio-therapy, as well as thermal and photo-thermal ablation, with the aim of finding out effective solutions to overcome the current obstacles of conventional therapeutic protocols. Within this work, we have reviewed and discussed the most recent injectable hydrogel systems, focusing on the structure and properties of the starting polymers, which are mainly classified into natural or synthetic sources. Moreover, mapping the research landscape of the fabrication strategies, the main outcome of each system is discussed in light of possible clinical applications.

Mucosal Applications of Poloxamer 407-Based Hydrogels: An Overview

Poloxamer 407, also known by the trademark Pluronic^® F127, is a water-soluble, non-ionic triblock copolymer that is made up of a hydrophobic residue of polyoxypropylene (POP) between the two hydrophilic units of polyoxyethylene (POE). Poloxamer 407-based hydrogels exhibit an interesting reversible thermal characteristic. That is, they are liquid at room temperature, but they assume a gel form when administered at body temperature, which makes them attractive candidates as pharmaceutical drug carriers. These systems have been widely investigated in the development of mucoadhesive formulations because they do not irritate the mucosal membranes. Based on these mucoadhesive properties, a simple administration into a specific compartment should maintain the required drug concentration in situ for a prolonged period of time, decreasing the necessary dosages and side effects. Their main limitations are their modest mechanical strength and, notwithstanding their bioadhesive properties, their tendency to succumb to rapid elimination in physiological media. Various technological approaches have been investigated in the attempt to modulate these properties. This review focuses on the application of poloxamer 407-based hydrogels for mucosal drug delivery with particular attention being paid to the latest published works.

Synthesis and Characterization of Lignin Hydrogels for Potential Applications as Drug Eluting Antimicrobial Coatings for Medical Materials

Lignin is the second most abundant biopolymer on the planet. It is a biocompatible, cheap, environmentally friendly and readily accessible material. It has been reported that these biomacromolecules have antimicrobial activities. Consequently, lignin (LIG) has the potential to be used for biomedical applications. In the present work, a simple method to prepare lignin-based hydrogels is described. The hydrogels were prepared by combining LIG with poly(ethylene glycol) and poly(methyl vinyl ether-co-maleic acid) through an esterification reaction. The synthesis took place in the solid state and can be accelerated significantly (24 vs 1 h) by the use of microwave (MW) radiation. The prepared hydrogels were characterized by evaluation of their swelling capacities and with the use of infrared spectroscopy/solid-state nuclear magnetic resonance. The prepared hydrogels showed LIG contents ranging between 40% and 24% and water uptake capabilities up to 500%. Furthermore, the hydrophobic nature of LIG facilitated loading of a model hydrophobic drug (curcumin). The hydrogels were capable of sustaining the delivery of this compound for up to 4 days. Finally, the materials demonstrated logarithmic reductions in adherence of Staphylococcus aureus and Proteus mirabilis of up to 5.0 relative to the commonly employed medical material poly(vinyl chloride) (PVC).

Hydrogels based on poly(methyl vinyl ether-co-maleic acid) and Tween 85 for sustained delivery of hydrophobic drugs

Hydrogels based on poly(methyl vinyl ether-co-maleic acid) and Tween 85 were prepared for hydrophobic drug delivery. The hydrogels were synthesized following a simple procedure carried out in solid state. The process did not require the use of any solvent and, as it is based on an esterification reaction, no toxic by-products were obtained. The resulting hydrogels contained Tween 85 inside the structure and due to the amphiphilic nature of this compound, hydrophobic domains within the hydrogel structure were formed. The obtained hydrogels showed good swelling capacities ranging from 100% to 600%. The esterification reaction that took place between poly(methyl vinyl ether-co-maleic acid) and Tween 85 was confirmed by infrared spectroscopy. Hydrogels were loaded with a hydrophobic drug model, Curcumin (CUR), showing that the hydrogels were able to retain up to 36 mg of CUR per g of hydrogel. Additionally, the synthesized hydrogels provided in vitro sustained CUR release over periods of up to 30 days. Finally, and due to the mucoadhesive nature of the prepared materials, one of the hydrogels was tested in vitro as an oral drug delivery system. For this purpose, the selected material was milled into microparticles (45-90 µm diameter). The release of CUR from the microparticles was evaluated under simulated gastric and intestinal conditions. The microparticles were able to release their cargos in 7 h. However, further work is required to optimize this system for oral drug delivery applications.

Reversed lipid-based nanoparticles dispersed in oil for malignant tumor treatment via intratumoral injection

Intratumoral injection of anticancer drugs directly delivers chemotherapeutics to the tumor region, offering an alternative strategy for cancer treatment. However, most hydrophilic drugs spread quickly from the injection site into systemic circulation, leading to inferior antitumor activity and adverse effects in patients. Therefore, we developed novel reversed lipid-based nanoparticles (RLBN) as a nanoscale drug carrier. RLBNs differ from traditional nanoscale drug carriers in that they possess a reversed structure consisting of a polar core and lipophilic periphery, leading to excellent solubility and stability in hydrophobic liquids; therefore, hydrophilic drugs can be entrapped in RLBNs and dispersed in oil. In vivo studies in tumor-bearing Balb/c nude mice indicated remarkable antitumor activity of RLBN-DOX after a single injection, with effective tumor growth inhibition for at least 17 days; the inhibition rate was ∼80%. These results can be attributed to the long-term retention and sustained drug release of RLBN-DOX in the tumor region. In contrast, intratumoral injection of free DOX showed weaker antitumor activity than RLBN-DOX did, with the tumor size doubling by day 11 and tripling by day 17. Further, the initial burst of drug released from free DOX could produce detrimental systemic effects, such as weight loss. Histological analyses by TUNEL staining showed apoptosis after treatment with RLBN-DOX, whereas tumor cell viability was high in the free DOX group. Current results indicate that RLBNs show sustained delivery of hydrophilic agents to local areas resulting in therapeutic efficacy, and they may be a promising drug delivery system suitable for intratumoral chemotherapy.

Synthesis and characterization of hyaluronic acid hydrogels crosslinked using a solvent-free process for potential biomedical applications

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A single step solid state crosslinking reaction has been developed to obtain hyaluronic acid hydrogels.

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The use of microwave radiation reduces significantly the crosslinking time.

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The synthesized materials allowed sustained release of a model molecule (methylene blue) for a period of up to 2 days.

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The material can be used to prepare micro-engineered devices such as microneedles through a micromoulding process.

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The resulting hydrogels showed anti-infective and bacteriostatic properties.

Hyaluronic acid (HA) is a natural linear polysaccharide that has been used extensively in the biomedical field as it is a biocompatible, biodegradable, nontoxic and non-immunogenic polymer with high water affinity. Besides, the presence of multiple acid and hydroxyl groups in the HA molecule makes it an ideal candidate for chemical modification. The present paper describes the synthesis and characterization of HA-based hydrogels. For this purpose, aqueous mixtures containing 5% (w/w) of HA and different concentrations of Gantrez S97 (GAN) (1, 3 and 5% w/w) were used to prepare HA-based hydrogels. The mixtures were dried and the hydrogels were obtained after heating the solid material at 80 °C for 24 h. GAN is the acid form of an methylvinylether and maleic anhydride copolymer and contains multiple acid groups that can form ester bonds when reacting with the multiple hydroxyl groups present in HA chains. The method described here present potential to be applied for the preparation of HA-based biomaterials with a defined form as the crosslinking reaction between HA and the crosslinker takes place in solid phase. Besides, the method can be considered an environmental-friendly process as no organic solvents or potentially toxic substances were used. The esterification reaction was confirmed by infrared spectroscopy and dynamic scanning calorimetry measurements. The loading and release capabilities of the hydrogels were evaluating by using methylene blue (MB) as a model molecule. The hydrogels showed a high affinity for MB showing loadings up to 0.35 mg MB per mg of hydrogel. Moreover, the hydrogels were capable of sustaining the MB release over two days. The use of microwave radiation was evaluated to reduce the crosslinking time from 24 h to 1 h, but this procedure needs to be optimized in future studies. As the crosslinking procedure takes place in solid state, the HA/GAN hydrogels were used to prepare micro-engineered device, microneedle arrays. Finally, the antimicrobial properties of the hydrogels were evaluated. The results showed that the hydrogels presented anti-infective properties.

Spray drying of silica microparticles for sustained release application with a new sol-gel precursor

A new precursor, tetrakis(2-methoxyethyl) orthosilicate (TMEOS) was used to fabricate microparticles for sustained release application, specifically for biopharmaceuticals, by spray drying. The advantages of TMEOS over the currently applied precursors are its water solubility and hydrolysis at moderate pH without the need of organic solvents or catalyzers. Thus a detrimental effect on biomolecular drug is avoided. By generating spray-dried silica particles encapsulating the high molecular weight model compound FITC-dextran 150 via the nano spray dryer Büchi-90, we demonstrated how formulation parameters affect and enable control of drug release properties. The implemented strategies to regulate release included incorporating different quantities of dextrans with varying molecular weight as well as adjusting the pH of the precursor solution to modify the internal microstructures. The addition of dextran significantly altered the released amount, while the release became faster with increasing dextran molecular weight. A sustained release over 35days could be achieved with addition of 60 kD dextran. The rate of FITC-Dextran 150 release from the dextran 60 containing particles decreased with higher precursor solution pH. In conclusion, the new precursor TMEOS presents a promising alternative sol-gel technology based carrier material for sustained release application of high molecular weight biopharmaceutical drugs.

In vitro evaluation of the genotoxicity of poly(anhydride) nanoparticles designed for oral drug delivery

In the last years, the development of nanomaterials has significantly increased due to the immense variety of potential applications in technological sectors, such as medicine, pharmacy and food safety. Focusing on the nanodevices for oral drug delivery, poly(anhydride) nanoparticles have received extensive attention due to their unique properties, such as their capability to develop intense adhesive interactions within the gut mucosa, their modifiable surface and their biodegradable and easy-to-produce profile. However, current knowledge of the possible adverse health effects as well as, toxicological information, is still exceedingly limited. Thus, we investigated the capacity of two poly(anhydride) nanoparticles, Gantrez^® AN 119-NP (GN-NP) and Gantrez^® AN 119 covered with mannosamine (GN-MA-NP), and their main bulk material (Gantrez^® AN 119-Polymer), to induce DNA damage and thymidine kinase (TK^+/-) mutations in L5178Y TK^+/- mouse lymphoma cells after 24h of exposure. The results showed that GN-NP, GN-MA-NP and their polymer did not induce DNA strand breaks or oxidative damage at concentrations ranging from 7.4 to 600μg/mL. Besides, the mutagenic potential of these nanoparticles and their polymer revealed no significant or biologically relevant gene mutation induction at concentrations up to 600μg/mL under our experimental settings. Considering the non-genotoxic effects of GN-NP and GN-MA-NP, as well as their exceptional properties, these nanoparticles are promising nanocarriers for oral medical administrations.

Luteinizing hormone-releasing hormone targeted poly(methyl vinyl ether maleic acid) nanoparticles for doxorubicin delivery to MCF-7 breast cancer cells

The purpose of this study was to design a targeted anti-cancer drug delivery system for breast cancer. Therefore, doxorubicin (DOX) loaded poly(methyl vinyl ether maleic acid) nanoparticles (NPs) were prepared by ionic cross-linking method using Zn(2+) ions. To optimise the effect of DOX/polymer ratio, Zn/polymer ratio, and stirrer rate a full factorial design was used and their effects on particle size, zeta potential, loading efficiency (LE, %), and release efficiency in 72 h (RE72, %) were studied. Targeted NPs were prepared by chemical coating of tiptorelin/polyallylamin conjugate on the surface of NPs by using 1-ethyl-3-(3-dimethylaminopropyl) carboiimid HCl as cross-linking agent. Conjugation efficiency was measured by Bradford assay. Conjugated triptorelin and targeted NPs were studied by Fourier-transform infrared spectroscopy (FTIR). The cytotoxicity of DOX loaded in targeted NPs and non-targeted ones were studied on MCF-7 cells which overexpress luteinizing hormone-releasing hormone (LHRH) receptors and SKOV3 cells as negative LHRH receptors using Thiazolyl blue tetrazolium bromide assay. The best results obtained from NPs prepared by DOX/polymer ratio of 5%, Zn/polymer ratio of 50%, and stirrer rate of 960 rpm. FTIR spectrum confirmed successful conjugation of triptorelin to NPs. The conjugation efficiency was about 70%. The targeted NPs showed significantly less IC50 for MCF-7 cells compared to free DOX and non-targeted NPs.

Recent progress in biomedical applications of Pluronic (PF127): Pharmaceutical perspectives

Most of the administered anti-cancer drugs are hydrophobic in nature and are known to have poor water solubility, short residence time, rapid clearance from the body and systemic side effects. Polymeric-based targeted particulate carrier system has shown to directly deliver the encapsulated anti-cancer drug to the desired site of action and prevent the interaction of encapsulated drug with the normal cells. Pluronic F127 (PF127) has been widely investigated for its broad-range of therodiagnostic applications in biomedical and pharmaceutical sciences, but rapid dissolution in the physiological fluids, short residence time, rapid clearance, and weak mechanical strength are the main shortcomings that are associated with PF127 and have recently been overcome by making various modifications in the structure of PF127 notably through preparation of PF127-based mixed polymeric micelles, PF127-conjugated nanoparticles and PF127-based hydrophobically modified thermogels. In this article, we have briefly discussed the recent studies that have been conducted on various anti-cancer drugs using PF127 as nano-carrier modified with other copolymers and/or conjugated with magnetic nanoparticles. The key findings of these studies demonstrated that the modified form of PF127 can significantly increase the stability of incorporated hydrophobic drugs with enhanced in vitro cytotoxicity and cellular uptake of anti-cancer drugs. Moreover, the modified form of PF127 has also shown its therapeutic potentials as therodiagnostics in various types of tumors and cancers. Hence, it can be concluded that the modified form of PF127 exhibits significant therodiagnostic effects with increased tumor-specific delivery of anti-cancer drugs having minimal toxic effects as compared to PF127 alone and/or other copolymers.

Synthesis and swelling peculiarities of new hydrogels based on the macromolecular reaction of anhydride copolymers with γ-aminopropyltriethoxysilane

This work describes the synthesis and macromolecular reactions of maleic anhydride (MA)-acrylamide (AAm) binary and MA-vinyl acetate (VA)- AAm ternary reactive copolymers with γ-aminopropyltriethoxysilane (APTS) as a polyfunctional crosslinker. Swelling parameters such as the start-time of the hydrogel-formation, initial rate of swelling, swelling rate constant, equilibrium swelling, and equilibrium water content (EWC) are determined for polymers/APTS/water systems with certain copolymer/crosslinker ratios (1.4/1 and 9/1). The formation of a hyperbranched network structure by the fragmentation of the side-chain reactive groups in the systems studied has also been confirmed by the Fourier Transform Infrared (FTIR) method.

A novel pH-responsive hydrogel based on natural polysaccharides for controlled release of protein drugs

A biocompatible and biodegradable hydrogel based on a natural polysaccharide was prepared, characterized and confirmed to be an effective and “smart” carrier for controlled protein delivery.