Polymer Ratio Research Articles

Ascorbic acid nanoencapsulation using polyelectrolyte complex formation and optimization using hybrid artificial neural network‐genetic algorithm

AbstractBackgroundsThe polyelectrolyte complex (PEC) formation using chitosan (Cs) and alginate (Alg) has been employed to carry out Vitamin C (VC) nanoencapsulation because of its instability in adverse conditions. This method includes VC nanoencapsulation using physical cross‐linking. The effect of the mixing order as well as the different mass ratios of both the polymer and the VC content, were investigated on the size, pdi, zeta potential, encapsulation efficiency (EE%), and yield%. Hence, considering different mass ratios of both polymer (4:1–1:4) and VC content (10%–30% w/w of Cs) as independent variables, PECs were formed using 0.1% (w/v) of Cs and Alg solution.ResultThe result showed that, for equal mass ratio (1:1) of Cs and Alg, the addition of Alg solution to Cs solution led to lower particle size, while higher particle size was observed with reverse order of addition. However, no significant effect of polymer mass ratios was observed on particle size and NPs stability, while EE varied with VC concentration. Artificial neural network (ANN) was applied to train the experimental parameters Cs: Alg ratios (X1:X2) and VC content (X3) for the output variables. Moreover, process optimization was carried out using multi‐objective genetic algorithm (MOGA) with the goal of lowering particle size and increasing EE while increasing nanoparticle yield.ConclusionThe PEC method effectively encapsulated VC as obtained from higher EE. The Cs: Alg ratio of 4:2.1 and 18% VC content (w/w of Cs) was found optimum for nanoencapsulation. The final ANN‐GA model showed an acceptable agreement with experimental data.

From Poly(glycerol itaconate) Gels to Novel Nonwoven Materials for Biomedical Applications.

Electrospinning is a process that has attracted significant interest in recent years. It provides the opportunity to produce nanofibers that mimic the extracellular matrix. As a result, it is possible to use the nonwovens as scaffolds characterized by high cellular adhesion. This work focused on the synthesis of poly(glycerol itaconate) (PGItc) and preparation of nonwovens based on PGItc gels and polylactide. PGItc gels were synthesized by a reaction between itaconic anhydride and glycerol. The use of a mixture of PGItc and PLA allowed us to obtain a material with different properties than with stand-alone polymers. In this study, we present the influence of the chosen ratios of polymers and the OH/COOH ratio in the synthesized PGItc on the properties of the obtained materials. The addition of PGItc results in hydrophilization of the nonwovens' surface without disrupting the high porosity of the fibrous structure. Spectral and thermal analyzes are presented, along with SEM imagining. The preliminary cytotoxicity research showed that nonwovens were non-cytotoxic materials. It also helped to pre-determine the potential application of PGItc + PLA nonwovens as subcutaneous tissue fillers or drug delivery systems.

Thermal analysis of sustainable and micro-filler Basalt reinforced polymer biocomposites for lightweight applications

For the past ten years, there has been a trend toward strengthening polymer composites with the help of natural fibers derived from plant and animal sources, which has led to ecological imbalance. Hence, to maintain the ecological balancing factors, the researchers and industrial experts are concentrating on the reinforcement of naturally available mineral materials in polymer products to minimize the polymer percentage and boost the economic feasibility of products with lightweight properties. In fact, incorporating basalt mineral into different polymer matrices is a highly creative notion that might open up some very interesting, uncharted territory. Basalt helps to create a pollution-free environment and balance ecological challenges by reducing the polymer ratio in the objects without many changes in their core properties. Basalt is desirable because of its outstanding thermal and mechanical characteristics, simplicity of processing, affordability, and lack of toxicity. Concerning these points, the current study aims to fabricate mineral particles (basalt)-reinforced (30 wt%) different polymers (synthetic epoxy, bio-epoxy, polyester, vinyl ester, polylactic acid, polypropylene, and high-density polyethylene) composite for lightweight thermal applications. The casting technique was used for the fabrication of thermoset polymer composites, whereas compression molding was employed to fabricate thermoplastic composites after an internal mixing process. The fabricated composites are subjected to thermogravimetric, thermomechanical, and dynamic mechanical analysis to analyze the thermal stability of the resultant composites. The Thermogravimetric analysis revealed that most of the samples exhibited good thermal stability with the addition of 30 wt% basalt fillers. As a result of moisture content as well as certain volatile compounds, if any, only a minimal weight loss in the range of 30 °C to 130 °C was seen at the early phase of heating for all neat and composite samples. The Thermomechanical analysis findings showed that basalt reinforcement at 30 wt% in synthetic epoxy, Polylactic acid, Polypropylene, and High Density Poly Ethylene polymers causes a reduction in dimensional variations up to 70 °C. This is because the basalt particles, particularly in the hard glassy area, limit the passage of molecules at lower temperatures. The higher stiffness of the basalt particles has significantly contributed to the viscoelastic properties of all the thermoset and thermoplastic composites. Because of the extreme closeness and thick packing of the components, which are in a dormant condition, the glassy areas in particular have a greater storage modulus. Based on these outcomes, these basalt-reinforced composites can be employed for lightweight thermal applications, which have the advantage of economic and eco-friendly features.

Nanofibers of chitosan-polycaprolactone blends as active support for photocatalytic nanoparticles: Outstanding role of chitosan in the degradation of an organic dye in water

Hybrid nanofibers of a chitosan-polycaprolactone blend containing titanium dioxide nanoparticles TiO2NPs, were prepared through electrospinning to study their adsorption and photocatalytic degradation capabilities of the model organic water pollutants, rhodamine B, RhB. To obtain uniform and bead-free nanofibers, an optimization of the electrospinning parameters was performed. The optimization was carried out by systematically adjusting the solution conditions (solvent, concentration, and polymer ratio) and instrumental parameters (voltage, needle tip-collector distance, and flow). The obtained materials were characterized by FT-IR, TGA, DSC, SEM, TEM, mechanical tensile test, and water contact angle. The photoactivity was investigated using a batch-type system by following UV–Vis absorbance and fluorescence of RhB.TiO2NPs were incorporated ex-situ into the polymer matrix, contributing to good mechanical properties and higher hydrophilicity of the material. The results showed that the presence of chitosan in the nanofibers significantly increased the adsorption of RhB and its photocatalytic degradation by TiO2NPs (5, 55 and 80 % of RhB degradation with NFs of PCL, TiO2/PCL and TiO2/CS-PCL, after 30 h of light irradiation, respectively), evidencing a synergistic effect between them. The results are attributed to an attraction of RhB by chitosan to the vicinity of TiO2NPs, favouring initial adsorption and degradation, phenomenon known as “bait-and-hook-and-destruct” effect.

Enhancement of Gypseous Soil Engineering Properties Through High-Density Polyethylene Polymer Addition: A Comprehensive Experimental Assessment

An experimental investigation was conducted to scrutinize the influence of high-density polyethylene (HDPE) polymer on the engineering properties of gypseous soil. Soil samples, possessing 38% gypsum content, were extracted from the Tikrit region, Iraq, and were subsequently subjected to varying HDPE polymer concentrations of 1%, 3%, and 6%. An observed augmentation in the maximum dry density was noted when a minuscule quantity of 1% HDPE polymer was incorporated. However, a subsequent increase in polymer concentration resulted in a discernible decrease in dry density. Examination via the double oedometer test elucidated a significant reduction in collapse potential by 64%, 77.7%, and 83.2% upon addition of 1%, 3%, and 6% HDPE polymer, respectively. Direct shear test outcomes revealed a complex influence of HDPE polymer on soil cohesion. In the dry state, a 1% and 6% HDPE polymer addition led to a cohesion increase by 50% and 16.67%, respectively, whereas a 33.3% decrease was observed at a 3% polymer concentration. Conversely, in the soaked state, cohesion was found to decrease by 50% at 1% and 6% HDPE polymer concentrations, and entirely diminished with a 3% polymer addition. Interestingly, the internal friction angle (ϕ) exhibited an increase in both dry and soaked states with escalating HDPE polymer percentages. A contradictory behavior was noted in the California Bearing Ratio (CBR), which decreased in the dry state but increased in the soaked state with a rise in HDPE polymer ratios. In conclusion, the present study substantiates that the addition of HDPE polymer induces modifications in the engineering behavior of gypseous soil. Further research is encouraged to optimize the HDPE polymer concentration for ground enhancement applications.

Facile fabrication of patterned polymeric films via phase separation-induced surface segregation

Films and surfaces with controlled patterns and features have attracted significant attention due to their widespread engineering applications. In this study, a new strategy based on phase separation-induced surface segregation is proposed. Different molecular chains in a polymer solution moved in different directions. During the segregation process, the molecular chains entangled with each other, hindering each other's migratory behavior, thus forming patterned structure on the surface of the film. Thin films with patterned surface topography were prepared by this method. The results indicate that the surface segregation phenomenon occurs during the film preparation. The surface structure of the films was influenced by the polymer ratio, solution concentration, thickness of the cast film and the solvent volatility. The fabricated films depict ordered topography, containing features with an average diameter of 2.23 μm when the polystyrene/poly(methyl methacrylate) ratio of 6:1, solution concentration of 10%, evaporation temperature of 30 °C, and a cast thickness of 0.1 mm were used. Therefore, based on simple blending combined with surface segregation strategy while optimizing the experimental conditions, patterned films with controlled topology were fabricated with preferred hydrophilic or hydrophobic characteristics. These observations are encouraging for the development of smart engineered surfaces with functional characteristics.

Lamellar structure formed from block copolymer for structural color

Certain brilliant colors in living species, such as, in plants, animals, insects, fungi, seaweed, and so on, known as structural colors, have attracted tremendous attention from researchers worldwide. Block copolymers are an interesting class of material that has been proven effective in fabricating structural colors due to their capability to self-assemble into structures on the scale of the wavelength of visible light. Lamellar structure is one of these structures. The demand on the high-quality structural colors in large scale application requires the easy modification of commercial block copolymers to obtain structural colors. In this project, a method to easily prepare structural colors is presented. First, an already commercialized block polymer was purchased. Then, the block copolymer is mixed with the small molecule guest to prepare a supramolecular complex solution. By slowly evaporating the solution, these supramolecular complexes can be assembled into a lamellar structure that displays structural color. By changing the ratio of polymer to small molecular guest and using different small molecular guests, polymer films of different colors can be obtained and tuned.

Application of temperature-sensitive hyperbranched polysiloxanes for the determination of polycyclic aromatic hydrocarbons in foodstuffs

In the present study, a novel temperature-sensitive hyperbranched polysiloxane dispersive liquid–liquid microextraction combined with high-performance liquid chromatography method (TS-HBPSi-DLLME-HPLC-UV) has been developed for the determination of five polycyclic aromatic hydrocarbons (PAHs) in instant noodles, in which temperature-sensitive hyperbranched polysiloxane (p(Ph-HBPSi-co-NIPAM)) was used as the extraction solvent. The method adsorbs the target analytes based on π-π and hydrophobic interaction between p(Ph-HBPSi-co-NIPAM) and PAHs, and then separates the polymer with the adsorbed target analytes from the solution by a phase transition. Microextraction parameters of the method including polymer ratio, type and concentration of salt, pH, extraction time and volume of acetonitrile were examined in detail and optimized. At the optimum conditions, the established method showed good linearity (R2 ≥ 0.9971) with satisfactory limits of detection (0.089–0.16 ng mL−1) and limits of quantitation (0.27–0.48 ng mL−1). The values for intra-day and inter-day precisions were lower than 3.2% and 4.4%, respectively. Enrichment factors (EFs) and extraction recoveries (ERs) ranged from 62 to 70 and 75 to 85%, respectively. Finally, the proposed microextraction technique was validated by analyte addition and recovery studies, and applied to the determination of five PAHs in instant noodles, demonstrating that temperature-sensitive hyperbranched polymers have great potential for application in sample pretreatment techniques.

The Effect Of Polymer Concentration On Coaxial Electrospinning Of Pvp/Pcl Core-Sheath Nanofibers

Core-sheath nanofibers are being developed with coaxial electrospinning for use in drug release studies. In this study, nanofiber structures were developed as hydrophobic PCL in the sheath and hydrophilic PVP in the core. The effect of polymer concentrations on fiber structure and water contact angle was observed by forming two different test groups. In the first group, fiber diameters were observed to decrease depending on viscosity as the polymer concentration decreased from 10% PCL / 10% PVP to 6% PCL / 6% PVP. It was also observed that the contact angle decreased from 104.3° to 57.61° as the concentration decreased. In the second group, the shell polymer ratio was kept constant as 10% wt PCL, while the core polymer ratio was decreased to 10 %, 8% and 6%. It was observed that the core polymer in the structure became hydrophilic as its viscosity decreased. Compared to the first group, the decrease in the contact angles of the surfaces was less since the shell polymer ratio was kept constant. Contact angles decreased from 104.3° to 96.29°.

Formulation and In vitro Cytotoxicity Studies of Avastin Nanoparticle Mediated Targeted Nose to Brain Drug Delivery System

Nanoparticles (NPs) occupy a superior place among the recent approaches experimented to deliver drugs into brain by circumventing the BBB such as chemical modifications. The Emulsification PEG-PLGA nanoparticles carrying drug were made using the solvent evaporation method. In summary, PEG-PLGA was dissolved in acetone (50 mL) and PLGA was dissolved in PEG-PLGA (50:50, 7-11 mg/mL). The Chitosan-Avastin conjugates were created in the lab in accordance with the procedures and guidelines outlined in Chitosan (3.25 m mol) was hydrated in 1 N HCl, then the appropriate amount of distilled water was added. After adding NaOH (5N) to the reaction mixture to get the pH down to 5, Avastin (6.48 mmol) was added while the mixture was continuously stirred. In-vitro studies the basic aim is to check the effect of various drugs on various cancer cell lines. For testing purpose a large number of human cancer cell lines have been screened. Cells are cultivated in 96-well culture plates, and the rate of cell multiplication, which determines the rate of cell growth, is indirectly measured by the dye's color intensity, which is directly inversely proportional to the number of cells present. Using doses between 10 and 100 g/mL, the MTT test was performed to examine the cytotoxicity various polymer ratios and formulations on human lung cancer lines-A549. For the determination of the percentage of viability of various samples, the cancer cells without receiving therapy were utilized as the control.

Formulation and evaluation of paclitaxel-loaded boronated chitosan/alginate nanoparticles as a mucoadhesive system for localized cervical cancer drug delivery.

Cervical cancer remains a significant global health challenge, and there is a need for innovative drug delivery systems to improve the efficacy of anticancer drugs. In this study, we developed and evaluated boronated chitosan/alginate nanoparticles (BCHIALG NPs) as a localized mucoadhesive drug delivery system for cervical cancer. Boronated chitosan (BCHI) was synthesized by incorporating 4-carboxyphenylboronic acid onto chitosan (CHI), and boronated chitosan/alginate nanoparticles (BCHIALG NPs) with varying polymer ratios were prepared using an ionic gelation method. The physical properties, drug loading capacity/encapsulation efficiency, mucoadhesive properties, and in vitro drug release profile of the nanoparticles were evaluated. The BCHIALG NPs exhibited a size of less than 390 nm and demonstrated high drug encapsulation efficiency (98.1 - 99.8%) and loading capacity (326.9 - 332.7 μg/mg). Remarkably, the BCHIALG NPs containing 0.03% boronated chitosan and 0.07% alginate showed superior mucoadhesive capability compared to CHIALG NPs, providing sustained drug release and they showed the most promising results as a transmucosal drug delivery system for hydrophobic drugs like paclitaxel (PTX). To the best of our knowledge, this is the first report investigating BCHIALG NPs for cervical drug delivery. The new mucoadhesive paclitaxel formulation could offer an innovative strategy for improving cervical cancer treatment.

Some Properties of Cement Mortar Modified by Styrene Butadiene Rubber

This research studies the effect of adding five different percentages of polymer (2, 4, 6, 8, and 10% of cement weight) on cement mortar's fresh and hardened properties, which was cured at laboratory temperature for 7, 14, and 28 days. Workability increases with increasing polymer. The workability value was lowest (25.6 and 29.4) % in mixtures containing 2% and 4% of (SBR). Increasing polymer ratios significantly decreased mechanical properties (compressive and flexural strength). Therefore, the best results were at 2% SBR and 4% SBR at 28 days of age. An inverse relationship was recorded between the increase in SBR ratios and polymer-modified cement mortar's compressive and flexural strength values. In general, the highest improvement in the water absorption and dry density resulted in better results with a decrease in the proportion of the polymer for all specimens of cement mortar containing 4% SBR polymer relative to the reference mixture.

Development of double crosslinked sodium alginate/chitosan based hydrogels for controlled release of metronidazole and its antibacterial activity

Double network sodium alginate/chitosan hydrogels were prepared using calcium chloride (CaCl2) and glutaraldehyde as the crosslinking agents by the ionotropic interaction method for controlled metronidazole release. The effect of polymer ratios and CaCl2 amount is investigated by the developing porosity, gel fraction, and extent of swelling in simulated physiological fluids. Interaction between the polymers with the formation of crosslinked structures, good stability, phase nature, and morphology of the hydrogels is revealed by Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy. A sodium alginate/chitosan hydrogel (weight ratio of 75:25) crosslinked with two percent CaCl2 is chosen for the in-situ loading of 200 mg of metronidazole. The drug release kinetics using different models show that the best-fit Korsmeyer-Peppas model suggests metronidazole release from the matrix follows diffusion and swelling-controlled time-dependent non-Fickian transport related to hydrogel erosion. This composition displays enhanced antimicrobial activity against Staphylococcus aureus and Escherichia coli.

Semiochemical delivery systems based on natural polymers to attract sand flies (Diptera: Psychodidae)

BackgroundThe successful use of semiochemicals to attract insects to traps is based on research on the most suitable compounds and their release profiles over time. Based on the group's promising results, matrices with a more adequate release profile and more eco-friendly properties for the release of 1-hexanol were developed. To use a more suitable prototype in the field, the most promising systems were added to a capsule and evaluated in a wind tunnel. Behavioral experiments were performed using the sand fly species, Lutzomyia longipalpis, to evaluate the efficacy of the proposed system.MethodsDifferent delivery systems were developed by varying the polymer (gellan gum and pectin) ratio, crosslinker (aluminum chloride) concentration, and glutaraldehyde removal.The delivery systems were loaded with 1-hexanol, and their release profiles were evaluated using gravimetric analysis under ambient and high-humidity conditions. When the matrix system was placed inside a plastic container, modulations in the active release profile were observed and the system could be reused. Actid attraction behaviors of the sand fly species, Lu. longipalpis, were evaluated in a wind tunnel when exposed to 1-hexanol-loaded release systems at different times.ResultsAmong the four formulations evaluated, System 2 (gellan gum and pectin in a 1:1 ratio with 5% aluminum chloride) exhibited the most promising release profile, with greater uniformity and longer compound release time. The maximum 1-hexanol release uniformity was achieved over a longer time, mainly every 24 h, under both ambient and high-humidity conditions. System 2 can be reused at least once with the same structure. The wind tunnel trials exhibited efficient activation and attraction of Lu. longipalpis to 1-hexanol after 24, 48, and 72 h in System 2 placed inside the capsules.ConclusionsThe polymeric matrix supplemented with 1-hexanol and introduced in plastic capsules showed promising results in attracting sand flies. This system can be used as a solution for other attractive compounds as well as in other applications where their release needs to be controlled or prolonged.Graphical

Influence of Excess Conjugated Wrapping Polymer in Semiconducting Single-Walled Carbon Nanotube Dispersions

Single-walled carbon nanotubes (SWNTs) are promising nanomaterials for incorporation into organic electronic devices (OEDs), with the potential to fabricate flexible devices while exploiting inexpensive solution-processing techniques. As-synthesized SWNTs are insoluble and comprised of a mixture of metallic and semiconducting SWNTs (sc-SWNTs), necessitating dispersal and purification before integration into OEDs. Refinement of conjugated polymer extraction techniques has allowed for the isolation of sc-SWNTs from metallic in a reproducible and scalable manner. The availability of highly-pure sc-SWNT materials has facilitated the production of thin-film transistors (TFTs) with very high charge carrier mobilities, outperforming organic small molecule and polymer semiconductors. However, the realization of commercial OED applications of polymer-sorted sc-SWNTs have not yet been achieved, partially due to the prohibitive time and materials costs associated with purifying sc-SWNTs.Current protocols for dispersing sc-SWNTs with conjugated polymers involve three broad steps: (1) dispersion of bulk SWNT material, (2) removal of non-dispersed carbonaceous materials, and (3) removal of excess polymer through filtration or centrifugation. The final step of removal of excess polymer is time-consuming and wasteful, but viewed as necessary for preparing high-performing TFTs, as the conjugated polymer has much lower performance compared to SWNTs.In this study we performed the first systematic investigation of the effect of excess polymer on SWNT TFT performance. Three SWNT concentrations were investigated, with varying ratios of excess polymer added to each. TFT device performance was monitored using several metrics, including: mobility, threshold voltage, on/off ratios and hysteresis. Characterization of large numbers of replicate TFT devices determined that below a threshold amount of excess polymer the presence of excess polymer did not have a negative impact on device performance. Detailed analysis of the sc-SWNT films through Raman spectroscopy and atomic force microscopy (AFM) confirmed that a simple rinsing step was sufficient to remove all the unbound conjugated polymer from the substrate surface without affecting the sc-SWNT network. The volume of solvent required for the rinsing step was substantially lower than that required for filtration or centrifugation steps. Furthermore, at higher SWNT concentrations the excess polymer prevented nanotube bundling, resulting in moderate improvements in both mobility and on/off ratios. Our results were reproducible for two different conjugated polymer sc-SWNT systems, demonstrating the versatility of this procedure.

Development of PCL-Based Gel Polymer Electrolyte for Li-Sulfur Batteries

Li-Sulfur batteries offer the next generation of energy storage beyond the current state of the art based on Li-intercalation with their high energy density (2640 Wh/kg) and S relative abundance on the earth's crust. Nevertheless, most Li-Sulfur battery systems use liquid electrolytes, which results in the formation of Li-metal dendrites and polysulfide redox shuttles resulting in the instability of the solid electrolyte interface layer, short-circuiting, poor cyclability, and self-discharge1. Our presentation will focus on efforts to create a polycaprolactone (PCL)-based gel polymer electrolyte (GPE) for Li-S batteries. GPE combines the high ionic conductivity of a liquid electrolyte with the polymer electrolytes' ability to block the redox shuttle and limit the Li-metal dendritic growth2. Furthermore, PCL provides for high electrochemical stability window (~5V vs. Li/Li+)3 and biodegradability that could ease the negative environmental impact associated with the battery industry.Moreover, effect of ceramic additives like LiNO3 and Li7La3Zr2O12 for enhancing ionic conductivity, mechanical stability and minimize the redox shuttle effect is also examined. We anticipate that the gel can be engineered to provide the high conductivity of a liquid electrolyte and the solid-state properties needed to block the polysulfide redox shuttle and limit dendrite growth. By determining the optimal ratio of polymer, additives, and solvent in the PCL gel formulation, we hope to benefit from hybridized ceramic/polymer electrolytes: nanocomposites engineered to optimize the advantages of polymers and ceramics while minimizing their weaknesses. References Pervez, Syed Atif, et al. Journal of Materials Chemistry A32 (2020): 16451-16462.Cui, Yingyue, et al. Chemistry–An Asian Journal(2022): e202200746.Fonseca, C. Polo, et al. " J. Electrochem. Sci2.2007 (2007): 52.

Development and Characterization of Gel-Based Buccoadhesive Bilayer Formulation of Nifedipine.

A promising controlled drug delivery system has been developed based on polymeric buccoadhesive bilayered formulation that uses a drug-free backing layer and a polymeric hydrophilic gel buccoadhesive core layer containing nifedipine. The DSC thermogravimetric analysis confirms the drug's entrapment in the gel layer and reveals no evidence of a potential interaction. Various ratios of bioadhesive polymers, including HPMC K100, PVP K30, SCMC, and CP 934, were combined with EC as an impermeable backing layer to ensure unidirectional drug release towards the buccal mucosa. The polymeric compositions of hydrophilic gel-natured HPMC, SCMC, and CP formed a matrix layer by surrounding the core nifedipine during compression. Preformulation studies were performed for all of the ingredients in order to evaluate their physical and flow characteristics. Ex vivo buccoadhesive strength, surface pH, swelling index, in vitro and in vivo drug release, and ex vivo permeation investigations were performed to evaluate the produced gel-based system. Rapid temperature variations had no appreciable impact on the substance's physical properties, pharmacological content, or buccoadhesive strength during stability testing using actual human saliva. It was clear from a histological examination of the ex vivo mucosa that the developed system did not cause any irritation or inflammation at the site of administration. The formulation NT5 was the best one, with a correlation coefficient of 0.9966. The in vitro and in vivo drug release profiles were well correlated, and they mimic the in vitro drug release pattern via the biological membrane. Thus, the developed gel-based formulation was found to be novel, stable, and useful for the targeted delivery of nifedipine.

Polymer Tablet Matrix Systems for the Controlled Release of Dry Betula pendula Leaf Extract.

The aim of the study was to develop polymer matrix tablets with modified release of dry Betula pendula leaf extract and to investigate basic parameters influencing the drug release pattern. To fully assess the statistical significance of the influence of the individual factors in the tablet formulation development as well as the combination of them, Tukey's tests and a complete 33 factor analysis of variance (ANOVA) were applied. The following three factors were studied at three levels (low, medium and high): influence of the hydrophobic/hydrophilic polymer ratio Ethylcellulose (EC)/Hydroxypropyl methylcellulose (HPMC) (40/60, 25/75 and 10/90), influence of HPMC molecular weight (500 kDa, 750 kDa and 1150 kDa), and influence of the compression force applied (1 t, 1.5 t and 2 t). The effect of these varied parameters on the drug release parameter t80 was evaluated statistically. Twenty-seven tablet models were formulated, including all possible combinations of the variables. The obtained drug release profiles demonstrated that a 25/75 (EC/HPMC) ratio was the most suitable for prolonging the release process. Increasing the molecular weight of HMPC from 500 kDa to 750-1150 kDa and applying higher compression force significantly influenced the studied t80 values and caused sustained drug release (t80 up to 7.97 h). The combination of the hydrophilic HPMC polymer with the hydrophobic EC can result in the formation of a promising drug-carrying matrix, offering effective control of the drug release process.

Development and Optimization of Fluvastatin Sodium Loaded Biodegradable Microspheres

Fluvastatin sodium is a hypolipidemic agent that reduces cholesterol synthesis by inhibiting HMG-COA reductase. The drug has a comparatively short biological half-life (1.2 hours) and low bioavailability (24– 29%), making it an appropriate candidate for a sustained-release drug delivery system. This study aimed to formulate biodegradable microspheres of fluvastatin sodium by optimization through an experimental design approach. Microspheres containing fluvastatin sodium were prepared by o/w emulsification solvent evaporation method using poly (lactic-co-glycolic acid) (PLGA 50:50) as a biodegradable polymer. 32 full factorial design was applied to study the effect of drug to polymer ratio and stirring speed on dependent variables, i.e. particle size, entrapment efficiency, Q1h, t80%. Prepared formulations were subjected to evaluate physicochemical properties and release characteristics. DSC and FTIR proved no interaction between the drug and excipients. Microspheres possessed size in the range of 193 to 344 μm and entrapment efficiency varied from 63.1 to 85.6%. Formulations showed drug release up to 23% within 1-hour. while t80% was found in between 3–9 hours. Regression analysis and ANOVA results suggested a significant effect (p<0.05) of variables on responses. The results of the present study suggested that biodegradable microspheres of fluvastatin sodium prepared using poly (lactic-co-glycolic acid) can be a promising alternative for conventional delivery and suitable for sustained drug release.

Formulation and in vitro evaluation of lamivudine loaded nanoparticles

Nanoparticles represent a promising drug delivery system of sustained and targeted drug release. They are specially designed to release the drug in the vicinity of target tissue. The aim of this study was to prepare and evaluate PLGA nanoparticles containing Lamivudine in different drug to polymer ratio. SEM indicated that nanoparticles have a discrete spherical structure. FT-IR studies indicated that there was no chemical interaction between drug and polymer and stability of drug. The in vitro release behavior from all the drug loaded batches was found to be Higuchi release and provided sustained release over a period of 12 h. The developed formulation overcome and alleviates the drawbacks and limitations of Lamivudine sustained release formulations and could possibility be advantageous in terms of increased bioavailability of Lamivudine.