Hydrophilic Gel Research Articles

Absorbent-Adsorbates: Large Amphiphilic Janus Microgels as Droplet Stabilizers.

Microgel particles are cross-linked polymer networks that absorb certain liquids causing network expansion. The type of swelling fluid and extent of volume change depends on the polymer-liquid interaction and the network's cross-link density. These colloidal gels can be used to stabilize emulsion drops by adsorbing to the interface of two immiscible fluids. However, to enhance the adsorption abilities of these predominantly hydrophilic gel particles, some degree of hydrophobicity is needed. An amphiphilic Janus microgel with spatially distinct lipophilic and hydrophilic sides is desired. Here, we report the fabrication of poly(ethylene glycol) diacrylate/poly(propylene glycol) diacrylate Janus microgels (JM) using microfluidic drop making. The flow streams of the two separate and immiscible monomer solutions are brought into contact and intersected by a third immiscible fluid in a flow-focusing junction to form Janus droplets. The individual droplets are cross-linked via UV irradiation to form monodispersed microgel particles with opposing hydrophilic and hydrophobic 3D-networked polymer matrices. By combining two chemically different polymer gel networks, an amphiphilic emulsion stabilizer is formed that adsorbs to the oil-water interface while its faces absorb their respective water or hydrocarbon solvents. The resulting water-in-oil emulsions are stabilized and destabilized via a thermal-responsive hydrogel. Stimuli-responsive droplets are demonstrated by adding a short-chain oligo ethylene glycol acrylate molecule to the hydrogel formulation on the Janus microgel particle. Droplets stabilized by these particles experience a sudden increase in droplet diameter around 60 °C. This work with absorbent particles may prove useful for applications in bio catalysis, fuel production, and oil transportation.

Targeted development of hydrophilic porous polysulfonamide gels with catalytic activity

We report the use of a template and functional monomers in the synthesis of three novel polysulfonamide gels with new architectures and functional groups. These mesoporous polysulfonamide gels were prepared by the condensation polymerization of benzene-1,3-disulfonyl chloride (as the main precursor), linear monomers, and cross-linkers (as variable precursors) in the presence of a silica template by a combination of sol-gel chemistry and the nanocasting technique. In this synthesis pathway, in situ polymerization onto the template surface led to the construction of a silica/polymer nanocomposite. Next, after removal of the template, the nanocomposite gels were transformed into mesoporous polysulfonamide nanospheres. After the physicochemical identification of the synthesized materials, functionalized polysulfonamides were used as reusable novel catalysts with high efficiency for the Strecker reaction under mild conditions. These polymers have Brønsted/Lewis acid active sites, a mesoporous structure, and hydrogen bonding. Moreover, since these polymers are hydrogels that can absorb water, they can promote the Strecker reaction through chemical absorption of the generated water as a driving force. Overall, this article describes a novel synthesis procedure and application of porous polysulfonamide gels.

Influence of Acid Etching and Universal Adhesives on the Bond Strength to Dentin.

The purpose of this study was to evaluate the influence of the application mode of three universal adhesive systems on interfacial physical properties of indirect composite restorations adhesively cemented to dentin cavities. Seventy-eight bovine lower incisors were selected and a slice of dentin (thickness: 2 mm) between the buccal surface and pulp chamber was obtained for each tooth. Conical cavities were made on this surface. The internal walls of the cavities were then coated with a hydrophilic gel, filled with composite resin and photopolymerized. The dentin/cone sets were divided into 6 groups (n=10) according to type of universal adhesive (TETRI: Tetric N Bond, FUT: Futura Bond U, SBU: Single Bond Universal) and acid etching on dentin (A: with acid etching; WA: without acid etching). The acid etching and the adhesive systems were applied to the surface of the dentin. All composite resin cones were sandblasted (Al2O3, 20 s) and silanized. After surface treatment, the cones were cemented (RelyX Ultimate) into the dentin cavity and photopolymerized. After thermocycling (10,000 cycles), samples were submitted to marginal adaptation analysis (using caries detector dye), push-out test (0.5 mm/min), and failure mode analysis. Additional samples were prepared for nanoleakage analysis (SEM). The data (MPa) were analyzed by two-way ANOVA and Tukey's post-test (5%). The groups in which the dentin was acid etched showed significantly lower bond strength values in the push-out test (p<0.01). Dentin acid etching significantly reduced the bond strength between universal adhesive systems and dentin in indirect restorative procedures.

Transcutaneous immunization with a highly active form of XCL1 as a vaccine adjuvant using a hydrophilic gel patch elicits long-term CD8+ T cell responses

Memory CD8+ cytotoxic T-lymphocytes (CTLs) play a key role in protective immunity against infection and cancer. However, the induction of memory CTLs with currently available vaccines remains difficult. The chemokine receptor XCR1 is predominantly expressed on CD103+ cross-presenting dendritic cells (DCs). Recently, we have demonstrated that a high activity form of murine lymphotactin/XCL1 (mXCL1-V21C/A59C), a ligand of XCR1, can induce antigen-specific memory CTLs by increasing the accumulation of CD103+ DCs in the vaccination site and the regional lymph nodes. Here, we combined a hydrophilic gel patch as a transcutaneous delivery device and mXCL1-V21C/A59C as an adjuvant to further enhance memory CTL responses. The transcutaneous delivery of ovalbumin (OVA) and mXCL1-V21C/A59C by the hydrophilic gel patch increased CD103+ DCs in the vaccination site and the regional lymph nodes for a prolonged period of time compared with the intradermal injection of OVA and mXCL1-V21C/A59C. Furthermore, the hydrophilic gel patch containing OVA and mXCL1-V21C/A59C strongly induced OVA-specific memory CTLs and efficiently inhibited the growth of OVA-expressing tumors more than the intradermal injection of OVA and mXCL1-V21C/A59C. Collectively, this type of hydrophilic gel patch and a high activity form of XCL1 may provide a useful tool for the induction of memory CTL responses.

Influence mechanism of fluorescent monomer on the performance of polymer microspheres

Abstract In order to quantitatively study the migration and retention of polymer microspheres in oil reservoirs, three kinds of fluorescent polymer microspheres P(AM-BA-AMCO), P(AM-BA-Ac-Flu) and P(AM-BA-RhB) were synthesized. Effects of fluorescent monomer on the performance of polymer microspheres were researched systematically. The results showed that addition of low concentration fluorescent monomers had no significant effect on initial particle size and swelling property of polymer microspheres. When the fluorescent monomers were added to microspheres, red shift of the luminescence spectrums occurred and the red shift distance of coumarin monomer was the shortest. The fluorescence intensity of microspheres was greater than that of fluorescent monomer itself, and the fluorescence intensity of the microsphere containing rhodamine monomer increased to a greater extent. The addition of fluorescent monomer could destroy the structure of hydrophilic polymer microsphere bulk gel to a certain extent and affect the creep performance of polymer microsphere bulk gel.

Gel-based Microemulsion Design and Evaluation for Topical Application of Rivastigmine.

The aim of the present study was to design nanocarriers for the topical application of rivastigmine. The effect of cosurfactants, hydrophilic gel and loading amount on the permeability of rivastigmine through rat skin was evaluated. Skin irritation tests and stability tests were performed to evaluate the utility of tested formulations. The results showed that the microemulsion formation and characteristics of drug-loaded formulations were related to many parameters of the components. When using microemulsion systems as a vehicle, the permeation rate remarkably increased about 13.2~24.3-fold and the lag time was significantly shortened from 24 h to 4.7 h. Formulations containing a cosurfactant of Diethylene Glycol Monobutyl Ether (DEGBE) showed higher enhancement effect, while increasing the loading dose from 0.5% to 5% further increased the flux about 2.1-fold and shortened the lag time. The drug-loaded experimental formulation did not cause skin irritation and had good stability at 20ºC and 40ºC storage for at least 3 months. The result showed that gel-based microemulsion formulation could be a promising approach for topical administration.

Characteristic of K3 (CpG-ODN) as a Transcutaneous Vaccine Formulation Adjuvant.

Transcutaneous immunization (TCI) is easy to use, minimally invasive, and has excellent efficacy in vaccines against infections. We focused on toll-like receptor (TLR) ligands as applicable adjuvants for transcutaneous formulations and characterized immune responses. TCI was performed using poke-and-patch methods, in which puncture holes are formed with a polyglycolic acid microneedle on the back skin of mice. Various TLR ligands were applied to the puncture holes and covered with an ovalbumin-loaded hydrophilic gel patch. During the screening process, K3 (CpG-oligonucleotide) successfully produced more antigen-specific antibodies than other TLR ligands and induced T helper (Th) 1-type polarization. Transcutaneously administered K3 was detected in draining lymph nodes and was found to promote B cell activation and differentiation, suggesting a direct transcutaneous adjuvant activity on B cells. Furthermore, a human safety test of K3-loaded self-dissolving microneedles (sdMN) was performed. Although a local skin reaction was observed at the sdMN application site, there was no systemic side reaction. In summary, we report a K3-induced Th1-type immune response that is a promising adjuvant for transcutaneous vaccine formulations using MN and show that K3-loaded sdMN can be safely applied to human skin.

Development and In vitro Evaluation of Nifedipine Gel Formulations for Anorectal Applications.

Current study focuses on the formulation and characterization of lipophilic and hydrophilic gel formulations of nifedipine to treat anal fissure via anodermal application. Lipophilic gels were prepared with Aerosil grades as gelling agents in bulk oils. Polyethylene glycols, hydroxypropyl methylcellulose, and Carbopol® 974P were used as gelling agents in water and propylene glycol for forming hydrophilic gels. The effect of repeated Freeze-Thaw Cycles (FT-C) on microstructures of the gels was investigated by examining viscosity, rheology and textural properties. Aerosil 200 containing lipophilic gels exhibited thixotropic behavior with plastic flow properties and higher viscosities. Accordingly, their compressibility and adhesiveness increased. FT-C caused notable changes in microstructures and textural properties of the lipophilic gels excluding the formulation containing Aerosil 200-in-isopropyl myristate. Among the hydrophilic gels, the viscosity of Carbopol® 974P gels increased depending on the amount of polymer, triethanolamine and water; these gels featured plastic flow without thixotropic behavior. Their compressibility and adhesiveness were higher than other gel formulations with stable post-FT-C characteristics. The higher flux values of nifedipine were observed from water containing Carbopol® 974P gel. The results of the stability tests showed that the Carbopol® 974P gel had a longer shelf life than the Aerosil 200-in-isopropyl myristate gel.

The substantiation of the technology of the bigel hydrophilic faction for the complex therapy of mastopathy in the aspect of methodological approaches to drug creation

Aim. To develop methodological approaches to creation of a bigel and substantiate the technology of the hydrogel fraction as one of the components of the bigel for the complex therapy of mastopathy and prevention of breast cancer.Materials and methods. The study objects were a hydrophilic gelling agent – hydroxyethyl cellulose (HЕС) and active pharmaceutical ingredients (AFI) – indomethacin, a liquid extract of hop cones (1 : 2), potassium iodide and magnesium sulfate. The methods of analysis of electronic and paper sources of information on advantages, technology, and methods of analysis of bigels were used. The methods of pharmacotechnological studies were applied when developing the technology and studying the critical parameters of the hydrophilic fraction of the bigel.Results. Over the last several decades, different types of gels have been widely studied as potential carriers for drug delivery. In recent years, many scientists proposed the development of formulations by mixing a hydrogel and an oleogel. These compositions are regarded as bigels. Since hydrogels are polar, while oleogels are non-polar, the bigel can be considered as emulsions with the internal and external immobilized phases. The advantages of the bigel system include the possibility of introducing both hydrophilic and lipophilic substances, providing the local action or transdermal drug delivery, improving the consumption properties of drugs. In addition, in the scientific papers of Almeida at el. it has been shown that bigel-based preparations have a moisturizing and cooling effect. Considering the number of advantages of the bigel systems over mono- and emulsion gels, the possibility of reproduction of their technology and research methods we can conclude that the development of this dosage form for the treatment of local and systemic diseases is promising. Because of the lack of soft medicines in the form of bigels at the domestic pharmaceutical market the aim of the work was to develop the composition and technology of a bigel for the complex therapy of mastopathy. The general methodological approach to pharmaceutical drug development (LP) is standardized in the ICH Q8 guidance, with which the guidance of ST-N MOH 42-3.0:2011 “Medicines. Pharmaceutical development (ICH Q8)” is harmonized. Taking into account the above we have proposed the algorithm for the methodological approach to the development of the composition of the hydrogel fraction as a component of the bigel for the complex therapy of mastopathy.Conclusions. The modern results of studying bigels in the world pharmaceutical practice (advantages, principles of development and analysis) have been analyzed and systematized. The methodological approach to the bigel development has been proposed. The technological parameters of the hydrogel fraction production and the rational way of introducing AFI to the composition of the hydrophilic gel base have been determined.

Mandibular Advancement Devices Prevent the Adverse Cardiac Effects of Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS)

Although considerable research highlights the interactions between obstructive sleep apnea-hypopnea syndrome (OSAHS) and cardiovascular diseases, the effect of mandibular advancement device (MAD) treatment on cardiovascular complications in OSAHS patients remains unclear. We evaluated the effect of OSAHS treatment with MADs on the myocardium. All methods in this study were in accordance with relevant guidelines and regulations of the medical ethics committee in Hospital of Stomatology, Hebei Medical University approved the work. Thirty New Zealand rabbits were randomized into three groups: the control group, Group OSAHS, and Group MAD. Hydrophilic polyacrylamide gel was injected into the soft palate of the rabbits to induce OSAHS. In Group MAD, a MAD was positioned after OSAHS induction. All animals were induced to sleep in a supine position for 4–6 h/day for 8 weeks. Echocardiography was used to determine the structure and function of the heart. The histological changes were detected by optical microscopy and transmission electron microscopy (TEM). The levels of ET-1(endothelin-1) and Ang II (Angiotensin II) in the plasma were measured by an enzyme-linked immunosorbent assay (ELISA). The expression of ET-1 mRNA in heart tissue was detected by RT-PCR. Histological abnormalities, left ventricular hypertrophy, and left ventricular dysfunctions were demonstrated in Group OSAHS, and the abnormities were rescued with MAD treatment. Higher levels of plasma ET-1 and Ang II and elevated expression of ET-1 mRNA in cardiac tissue were detected in Group OSAHS compared with Group MAD and the control group. The blood oxygen saturation was negatively correlated with the levels of ET-1 and Ang II. OSAHS-induced elevated levels of ET-1 and Ang II may be attributed to myocardial structural abnormalities and dysfunction. Early treatment of MADs may play an important role in preventing myocardial damage in OSAHS rabbit model.

Selective separation of Cd(II) and Am(III) by coating pH-responsive hydrophilic gel on silica particles

ABSTRACT An N-isopropylacrylamide(NIPA) gel can swell and shrink in response to temperature and pH, and metal ion adsorption using NIPA gel containing N,N,N’,N’-tetrakis(2-methylpyridyl)ethylenediamine(TPEN) derivatives also follows this behavior. Here, we prepare novel TPEN-type-NIPA gel-coated porous silica particles with high TPEN content. The particles are highly effective in selective separation; they exhibit high selectivity to Cd(II) at pH 2, at low temperature. The novel TPEN-type-NIPA gel-coated porous silica particles exhibit a high Am(III)/Eu(III) separation factor of ~14 at pH 4, at which the selectivity to Am(III) is high. Hence, these particles will aid in the extraction of Am(III).

Evaluation of hydrophilic gel made from Acemannan and Moringa oleifera in enhancing osseointegration of dental implants. A preliminary study in rabbits

BackgroundHydrophilic implant surface has gained increasing interest as a factor to stimulate osseointegration. PurposeThe study was done to formulate hydrophilic gel to be applied on to the dental implant surface, to enhance bone to implant contact (BIC). Materials and methodsIn first part of study, Acemannan and Moringa oleifera hydro gel formulated in different proportions were coated on the titanium disk and 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay was done to evaluate cell viability.Cytotoxicity of aqueous extracts of two plants were tested against UMR106 cells. In second part of study, the prototype titanium implants were placed in tibia and femur of 8 male rabbits. Hydrophilic gel formulated from Acemannan and Moringa oleifera were coated on the study groups of implants. Histomorphometric analysis was carried out of the enbloc sections specimens. Student's unpaired t-test was used to compare mean values between the two groups. ResultsThe alkaline phosphatase assay showed least cell inhibition for Acemannan and Moringa oleifera (2:1) as 4.45% and osteoblastic differentiation as 0.328 at 540 nm. Titamium disc coated with hydrogel of Acemannan and Moringa oliefera and seeded with Human MSC shows increased proliferation of osteoblast cells.Compare to study group implants, control group showed no new bone formation. ConclusionsHydrophilic implant surface showed new bone formation with increased bone to implant contact.There was absent of degenerative changes, necrotic changes, fibrosis, and inflammation at the new BIC.

Influence of Acetylated Annealed Starch on the Release of β-Escin from the Anionic and Non-Ionic Hydrophilic Gels.

Naturally sourced products introduced to human nutrition and rediscovered for therapy include polysaccharides from potatoes. The starch may obtain unique properties via acetylation with acetic anhydride at 13 cm3/100 g of starch as the basic dose of reagent used in industrial conditions. The hydrogel formulation was applied as a carrier for escin included in the dry extract of Aesculus hippocastanum. Six hydrogels were evaluated (methylcellulose, polyacrylic acid-Carbopol 980 NF and polyacrylate crosspolymer 11—Aristoflex Velvet) with various concentrations of the modified starch. The kinetic studies of in vitro β-escin release were carried out in purified water at 37 ± 0.5 °C using a paddle apparatus at 50 rpm and a time period of 7 h. The criterion for the most suitable model was based on a high correlation coefficient of evaluated release profiles. The addition of modified annealed acetylated potato starch resulted in prolongation of β-escin release.

Immunogenicity of Milk Protein-Containing Hydrophilic Gel Patch for Epicutaneous Immunotherapy for Milk Allergy.

Epicutaneous immunotherapy (EPIT) involving the skin's immune system is easy to use, painless and has a low risk of systemic side effects; it can be applied to food allergies that have a high morbidity rate in children. In this study, we evaluated the safety and efficacy of hydrophilic gel patch (HG) for EPIT. Milk protein concentrate (MPC)-containing HG was applied to the skin that maintained a barrier function or formed puncture holes with microneedle, and MPC-specific antibodies were measured. The clinical study was conducted involving patients with severe milk allergy. No specific immune response was induced when immunizing to intact skin, and antibody production was observed by forming puncture holes. It was suggested that MPC contained in HG has immunogenicity and a very small amount of MPC was delivered to intact skin. In the clinical study, the symptom induction threshold increased in four of eight subjects, allowing them to consume milk and switch to oral immunotherapy. Although local skin reactions and temporary elevation of specific IgE antibodies were observed, no systemic side effects appeared throughout the study. EPIT using HG is a safe method to enable oral administration even in patients with severe milk allergies.

The Influence of Different Concentrations of a Natural Clay Material as Active Principle in Cosmetic Formulations

Abstract The clay minerals have characteristics and properties that allow their applicability in the cosmetic area, being incorporated into formulations as an active principle. Therefore, the aim of this work is characterizing and evaluating the influence of a clay from Miracema do Norte, Tocantins, Brazil, named Clay V, on the physicochemical characteristics of a hydrophilic gel of Aristoflex®, a copolymer of the neutralized acryloyldimethyltaurate and vinylpyrrolidone sulphonic acid. Clay V was decontaminated and characterized through microbiological evaluation, crystalline phases present by X-Ray Diffraction (XRD), chemical composition by X-Ray Fluorescence (XRF), thermogravimetric analysis (TGA) and granulometric distribution by sieving. Gels were prepared using Clay V with particles in the range ≤ 180 μm in three different concentrations: 1%, 3% and 5% (w/w) and a standard gel without clay. The formulations were evaluated according to organoleptic characteristics, pH, viscosity, spreadability and the centrifugation test. The microbiological evaluation showed that the clay sample is in compliance with the parameters established by the legislation. The following mineral phases were identified by XRD: kaolinite, illite, vermiculite and quartz, mainly composed of silica and alumina according to XRF. Thermal analysis showed that the clay has two thermal decomposition reactions, the largest being 547.6°C. The granulometric analysis identified that the largest fraction (63.22%) was of particles with sizes greater than 710 μm. The organoleptic characteristics presented by the formulations were suitable, with characteristic gel odor, homogeneous appearance, soft and refreshing texture and staining based on the concentration of Clay V used. The obtained pH values were within the range between 5.5 and 6.5, and it was verified that the gel has high spreadability, distributing evenly on the skin. The values obtained for viscosity showed that the formulations are non-Newtonian fluids with pseudoplastic behavior. The centrifugation test showed that the formulations are stable, with no phase separation. The results obtained with the tests showed that the natural clay V material is beneficial in cosmetic products and can be used for incorporation in cosmetic gel formulations of Aristoflex® type.

Characterization and electron transport properties of polyaniline nanocomposites containing silver chloride nanoparticles embedded on the gelatin surface

ABSTRACTPolyaniline (PANI) encapsulating silver chloride nanoparticles embedded on the surface of gelatin nanofibers were prepared. The interaction of PANI/gelatin with AgCl and crystallinity of the composites are characterized by FTIR and XRD. The surface framework of the composites was studied by SEM and TEM. Increase of AgCl has brought out significant increase of DC conductivity of the composites. The hydrophilic GEL acts as a plasticizer in the PANI/GeL-AgCl increases the mobility of charge carriers in the composites which influences the conductivity. Such composites are used in electric devices, sensors, and functional coatings for their high electrical conductivity.

Description of 101 cases of nipple cracks and risk factors via case–control study in eight units of a perinatal network

Nipple crack are a frequent complication of breastfeeding, causing pain for the mother and feeding difficulties for the baby with the risk of early cessation of breastfeeding. The characteristics of nipple cracks have rarely been described. Treatment varies according to the period of breasfeeding and the maternity ward. Eight maternity wards in a perinatal health network in western France followed up maternal nipple cracks. The cracks were described and their treatment was noted. The variables regarding the mothers, delivery conditions, health of newborns, and their ability to breastfeed were analyzed. Each case patient was matched with a control patient who was in a room adjacent to the case patient. Case–control analysis was univariate, followed by multivariate analysis via logistic regression (SPSS 20.0) with adjusted odds ratios (aOR). In all, 101 cases of women with nipple cracks were studied. The cracks were predominantly located in the upper external quadrants as well as in the central part of the nipple. There were no lateralization effects (right or left). The most frequent treatments after breastfeeding were oils, hydrophilic gel, and maternal milk. Compared with the 101 controls without cracks, the features associated with cracks in multivariate analysis were fair skin (aOR=1.92 [1.01–3.60]; P=0.04), history of nipple cracks (aOR=11.38 [3.69–35.13]; P=0.0001), first breastfeeding (aOR=4.21 [1.27–13.86]; P=0.018), and normal weight or no obesity (aOR=0.33 [0.14–0.75]; P=0.008). Two more specific analyses were performed in primiparous and multiparous women. In conclusion, the practitioners learned to describe nipple cracks and analyze their treatments. Knowledge of the risk factors should enable practitioners to propose active prevention to mothers with fair skin, a history of cracks, or a lack of experience in breastfeeding by helping them to breastfeed during the first days of their infant's life, especially for primiparous and overweight or obese women.

Development of an Immune Regulation Technology Targeting the Skin and Promotion of the Practical Applications of Transcutaneous Vaccination/Immunotherapy

In the premise of vaccination and allergen-specific immunotherapy, transcutaneous formulations have an advantage over conventional subcutaneous injections in terms of convenience, simplicity of delivery, and painless administration into the skin. Additionally, since transcutaneous formulations can be rendered cold-chain free, they do not require expert handling during transportation, storage, and stockpiling, which enables reductions in costs and distribution to distant areas. Furthermore, transcutaneous formulations are effective for improving adherence in children with phobias toward injection needles and may help in persuading them to perform self-vaccination and home immunotherapy against allergies in the future. We have been promoting the development of innovative "patch-type formulations for vaccination and immunotherapy" which regard skin as an immune organ and utilize our original transcutaneous administration devices (hydrophilic gel patch and microneedle patch) for their delivery. We have confirmed the safety and efficacy of transcutaneous formulations not only in demonstration experiments using animals but also in physician-initiated clinical studies. Additionally, in order to elucidate the mechanism for the induction of immune responses by transcutaneous formulations, we analyzed the immunological events occurring in the skin and regional lymph nodes which accompanied the application of transcutaneous administration devices or the delivery of antigens (vaccines and allergens) to the skin surface layer. This review presents our results from basic to clinical research on the development of transcutaneous formulations for vaccines and allergen-specific immunotherapy.

FORMULATION AND IN VITRO CHARACTERISATION OF SOYBEAN OIL-HPMCK4M BASED BIGEL MATRIX FOR TOPICAL DRUG DELIVERY

Objective: Hydrogels with scope for utilization in numerous fields possess limited applications due to problems in incorporating wide range of drugs and crossing the lipophilic barrier of the skin. Attempts to overcome these problems by developing organogel hold drawbacks. Challenges posed by drug lipophilicity or skin permeation can be solved by developing bigel formed via combination of lipophilic and hydrophilic gel phases in a definite proportion. The objective of the present study is to formulate and characterize matrix type bigel of soybean oil and HPMCK4M for topical drug delivery.&#x0D; Methods: Four batches of bigels were developed with two organogel formulations of soybean oil containing 20 and 22% w/v Span 60. Both organogels and bigels were examined for compatibility by FTIR spectroscopy, hemocompatibility and characterized for physical appearance, pH, rheological behavior and in vitro drug release pattern.&#x0D; Results: FTIR study confirmed compatibility between paracetamol and components of organogel or bigel. The oily feel of organogels disappeared with bigels which possessed a creamy and smooth texture. Pseudoplastic behaviour was confirmed by Ostwald-de wale power-law model in both organogels and bigels. Improved drug release was observed in bigel (BG1) formulation containing 3%w/v HPMCK4M and soybean oil based organogel with 20% w/v Span 60 as compared to the corresponding organogel (OG1). Organogels were foundto follow either zero-order kinetics (OG1) or Korsmeyer-Peppasmodel (OG2) while the formation of matrix was exhibited in bigels with drug diffusion predominantly of non-Fickian type.&#x0D; Conclusion: Therefore, bigels of soybean oil based organogel with HPMCK4M hydrogel formed gel matrix demonstrating improved drug release for topical application compared to organogel.

Graphene quantum dots nanoparticles changed the rheological properties of hydrophilic gels (carbopol)

Graphene quantum dots (GQDs) have special properties at nanosize zone, as highly tunable photoluminescence, electrochemiluminescence and multiphoton excitation, that make them promising nanoagents for drug delivery systems. In this direction the use of gels to formulate nanodrugs, for both in vitro and in vivo assay is required. However, the presence of GQDs nanoparticles may affect the rheological parameters. These changes may influence the biological behavior of this formulation as change the pharmacological application. In this study we evaluated the effect of adding GQDs to carbopol gels formulation, in terms of rheological properties. In this direction, carbopol gels alone and loaded with GQDs were studied. The results of pure carbopol formulation showed a non-Newtonian, pseudo-plastic fluid without thixotropic behavior. Otherwise, the presence of GQDs in the carbopol formulation (carbopol loaded with GQDs) caused a reduction on the viscosity and modified the interactions between the polymer chains leading to the transformation of the initial gel into a viscous fluid. This alteration can change drastically the use of these formulations, especially for drug delivery, since slightly changes in viscosity can influence the occlusion, retention and permeability of these nanoparticles into biological barriers.