Hydroxypropyl Cellulose Polymer Research Articles

The potential of new eco-friendly formulations in enhancing the protection of ceramic artifacts

This study focuses on transforming the consolidation formulations based on Hydroxypropyl cellulose (HPC), which is an eco-friendly bio-based cellulosic polymer with inherent hydrophilic characteristics to a hydrophobic one. This will be done via integrating the polymer with nano-silica and hydrophobic nano-silica, to enhance its consolidating properties to be in line with the global trend of replacing conventional materials with eco-friendly alternatives. Three different formulations were prepared, including HPC polymer solely, HPC integrated with nano-silica (NS), and HPC integrated with hydrophobic nano-silica (HNS). Primarily, nano-silica and hydrophobic nano-silica were synthesized and characterized using TEM and XRD. Subsequently, the prepared formulations were applied to artificial ceramic artifacts to evaluate their physical and mechanical properties, encompassing parameters such as water absorption, color change, contact angle, SEM/EDX, and digital microscopy. The results revealed that the incorporation of hydrophobic nano-silica significantly enhanced the mechanical and the physical properties of the cellulosic polymer, besides the extreme change that happened to its hydrophilic properties which was developed to a very good hydrophobic one. The success of these consolidation formulations can pave the way for the utilization of bio-based polymers with their inherent eco-friendly nature in the consolidation and restoration processes of cultural heritage artifacts, which can help in the contribution to the expanding body of knowledge in sustainable materials for conservation purposes.

Phase homogeneity in ternary amorphous solid dispersions and its impact on solubility, dissolution and supersaturation – Influence of processing and hydroxypropyl cellulose grade

As performance of ternary amorphous solid dispersions (ASDs) depends on the solid-state characteristics and polymer mixing, a comprehensive understanding of synergistic interactions between the polymers in regard of dissolution enhancement of poorly soluble drugs and subsequent supersaturation stabilization is necessary. By choosing hot-melt extrusion (HME) and vacuum compression molding (VCM) as preparation techniques, we manipulated the phase behavior of ternary efavirenz (EFV) ASDs, comprising of either hydroxypropyl cellulose (HPC)-SSL or HPC-UL in combination with Eudragit® L 100–55 (EL 100–55) (50:50 polymer ratio), leading to single-phased (HME) and heterogeneous ASDs (VCM). Due to higher kinetic solid-state solubility of EFV in HPC polymers compared to EL 100–55, we visualized higher drug distribution into HPC-rich phases of the phase-separated ternary VCM ASDs via confocal Raman microscopy. Additionally, we observed differences in the extent of phase-separation in dependence on the selected HPC grade. As HPC-UL exhibited decisive lower melt viscosity than HPC-SSL, formation of partially miscible phases between HPC-UL and EL 100–55 was facilitated. Consequently, as homogeneously mixed polymer phases were required for optimal extent of solubility improvement, the manufacturing-dependent differences in dissolution performances were smaller using HPC-UL, instead of HPC-SSL, i.e. using HPC-UL was less demanding on shear stress provided by the process.

Raman spectroscopy investigations of hydrated hydroxypropyl cellulose mixtures with low-soluble salicylic acid: Molecular interactions and the water-binding structure

Highly hydrophilic polymer matrices are limited their in use to the delivery of hydrophilic drugs, and are ineffective for hydrophobic compounds. Therefore, studying hydrogels that can effectively deliver hydrophobic drugs is still an important challenge. The molecular interactions occurring in model hydrated binary mixtures of hydroxypropyl cellulose (HPC) and low-soluble and hydrophobic salicylic acid (SA) (1:1 w/w) were investigated by means of Raman spectroscopy. During the study, the OH stretching vibrations region (in the 3600–3100 cm−1 range) was examined and bands for the three assessed fractions of water were assigned at the wavenumbers 3400 cm−1 (non-freezing water), 3320 cm−1 (freezing bound water) and 3220 cm−1 (free water). The contribution of the OH vibrations of SA (3205 cm−1) was also considered. A significant area for the analysis of changes in the HPC polymer is the glycosidic linkage vibration region ranging from 1250 cm−1 to 1000 cm−1 (at ∼1151 cm−1 and at ∼1093 cm−1) and the 3000–2850 cm−1 region due to the CH stretching of the CH2 and CH3 groups. SA is able to form hydrogen bonds to polymer chains and to water, as well as to another SA molecule to form a dimer. Therefore, bands derived from SA were observed to monitor these interactions (in the 1600–1500 cm−1 range).The obtained results were discussed and partially compared to the corresponding previously published spectroscopic and theoretical outcomes. All observed interactions between the components of the mixture and water molecules were also analyzed as a function of time, which is a novel approach providing a large amount of valuable information about the system. The applied methodology allowed for establishing that the stabilization of the hydrated HPC/SA system took place after one week. The greatest dynamics of changes were observed for the lowest studied water concentration. For the highest water concentration, several low-intensity bands in the CO vibration range seemed to indicate dimer-type interactions.

Antifungal and consolidation properties of linen textiles treated with silver nanoparticles loaded on hydroxypropyl cellulose polymer

Microorganisms are considered one of the most dangerous deterioration factors to cellulosic textiles, especially textiles made of linen fibers. Many of the traditional methods of resistance to microorganisms that infect textiles were used in the past, but they were of low effectiveness and high toxicity for those who applied these methods. The study used silver nanoparticles (AgNPs) prepared by the chemical reduction of silver nitrate (AgNO3) in the presence of a polyvinylpyrrolidone (PVP) polymer as a stabilizing agent in inhibiting fungal strains Aspergillus flavus, Trichoderma sp. and Penicillium duclauxii that were isolated from the ancient linen piece No. 1345 preserved in the Sohag National Museum. The properties of the silver nanoparticles prepared and loaded on hydroxypropyl cellulose (Klucel G 1%) polymer were studied by many of examination and analysis methods such as TEM, XRD and FTIR. Evaluating the effectiveness of AgNPs/Klucel G by using well-cut diffusion technique revealed that the best concentration of AgNPs in inhibiting fungal strains is 3%. The results of treating raw and dyed linen textiles using AgNPs/Klucel G also indicated an improvement in the mechanical and chemical properties of the treated textiles. One of the most important results of the study is obtaining raw and dyed linen textiles with resistant properties to isolated fungal strains up to 3 months of treatment.Graphical

Tailored ASD destabilization - Balancing shelf life stability and dissolution performance with hydroxypropyl cellulose

Amorphous solid dispersion (ASD) formulations are preferred enabling formulations for poorly water soluble active pharmaceutical ingredients (API) as they reliably enhance the dissolution behavior and solubility. Balancing a high stability against unwanted transformations such as crystallization and amorphous phase separation during storage on the one hand and optimizing the dissolution behavior of the formulation (high supersaturation and maintenance for long time) on the other hand are essential during formulation development. This study assessed the potential of ternary ASDs (one API and two polymers) containing the polymers hydroxypropyl cellulose together with poly(vinylpyrrolidone-co-vinyl acetate) (PVP VA64) or hydroxypropyl cellulose acetate succinate to stabilize the amorphously embedded APIs fenofibrate and simvastatin during storage and to enhance the dissolution performance. Thermodynamic predictions using the PC-SAFT model revealed for each combination of polymers the optimal polymer ratio, maximum API load that is thermodynamically stable as well as miscibility of the two polymers. The stability predictions were validated by three months enduring stability tests, followed by a characterization of the dissolution behavior. The thermodynamically most stable ASDs were found to be the ASDs with deteriorated dissolution performance. Within the investigated polymer combinations, physical stability and dissolution performance opposed each other.

Effect of pH, Ionic Strength and Agitation Rate on Dissolution Behaviour of 3D-Printed Tablets, Tablets Prepared from Ground Hot-Melt Extruded Filaments and Physical Mixtures

With the current focus on 3D-printing technologies, it is essential to understand the processes involved in such printing methods and approaches to minimize the variability in dissolution behaviour to achieve better quality control outcomes. For this purpose, two formulations of theophylline tablets were prepared using hydroxypropyl cellulose (HPC) and ethyl cellulose (EC). Among the two types of tablets, three different methods (physical mixture (PM), hot-melt extrusion (HME) and 3D-printing fused deposition modelling (FDM)) were applied and their dissolution behaviours were studied under various conditions using a biodissolution tester. This was carried out at pH values of 1.2, 2.2, 5.8, 6.8, 7.2 and 7.5, mimicking the medium in the gastrointestinal tract. Dissolution tests under two dipping rates (10 dpm and 20 dpm) and two ionic strengths (0.2 M and 0.4 M) were conducted to mimic fed and fasting conditions. The dissolution efficiency (DE%), release rate, similarity factor (f2) and difference factor (f1) were calculated. When comparing the DE%, the formulation containing EC showed less sensitivity to changes in the dipping rate and ionic strength compared to the HPC formulation. As for the manufacturing method, 3D-printing FDM could improve the robustness of the dissolution behaviour of both formulations to dipping rate changes. However, for ionic strength changes, the effect of the manufacturing method was dependent on the formulation composition. For example, the 3D-printed tablets of the HPC formulation were more sensitive to changes in ionic strength compared to the EC-containing formulation. The release mechanism also changed after the thermal process, where n values in the Korsmeyer-Peppas model were much higher in the printing and HME methods compared to the PM. Based on the formulation composition, the 3D-printing method could be a good candidate method for tablets with a robust dissolution behaviour in the GI tract. Compared to HPC polymers, using hydrophobic EC polymers in printable formulations can result in a more robust dissolution behaviour in fed and fasting states.

Design and optimization of ciprofloxacin hydrochloride biodegradable 3D printed ocular inserts: Full factorial design and in-vitro and ex-vivo evaluations: Part II

Coupling hot-melt extrusion (HME) with fused deposition modeling three-dimensional printing (FDM-3DP) can facilitate the fabrication of tailored, patient-centered, and complex-shaped ocular dosage forms. We fabricated ciprofloxacin HCl ocular inserts by coupling high-throughput, solvent-free, and continuous HME with FDM-3DP. Insert fabrication utilized biocompatible, biodegradable, bioadhesive Klucel™ hydroxypropyl cellulose polymer, subjected to distinct FDM-3DP processing parameters, utilizing a design of experiment approach to achieve a tailored release profile. We determined the drug content, thermal properties, drug-excipient compatibility, surface morphology, in vitro release, antibacterial activity, ex-vivo transcorneal permeation, and stability of inserts. An inverse relationship was noted between insert thickness, infill density, and drug release rate. The optimized design demonstrated an amorphous solid dispersion with an extended-release profile over 24 h, no physical or chemical incompatibility, excellent mucoadhesive strength, smooth surface, lack of bacterial growth (Pseudomonas aeruginosa) in all release samples, and prolonged transcorneal drug flux compared with commercial eye drops and immediate-release inserts. The designed inserts were stable at room temperature considering drug content, thermal behavior, and release profile over three months. Overall, the fabricated insert could reduce administration frequency to once-daily dosing, affording a promising topical delivery platform with prolonged antibacterial activity and superior therapeutic outcomes for managing ocular bacterial infections.

Physicochemical and Pharmacokinetic Evaluation of Praziquantel Co-Crystals by Varying the Spacer Group of Co-Crystal Formers

The research work focuses on investigating the effects of spacer group (varying aliphatic chain length=n) of co-crystal formers (oxalic acid (OA, n=0), (malonic acid (MA, n=1), (succinic acid (SA, n=2), (glutaric acid (GA, n=3), and (adipic acid (AA, n=4) on the physicochemical properties and oral bioavailability of praziquantel (PZQ) co-crystals. For this purpose, different co-crystals of PZQ with dicarboxylic acid co-crystal formers (OA, MA, SA, GA, and AA) were synthesized. These co-crystals were characterized by powder X-ray diffractometry (XRPD), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetry (TG) techniques. The in-vitro (solubility and dissolution) and in-vivo pharmacokinetic (P.K) studies were performed for PZQ co-crystals. Additionally, the effect of polymer hydroxypropyl cellulose (HPC) on the formation of PZQ co-crystals was also investigated. According to the study results, PZQ-SA co-crystal showed improved solubility, dissolution, and oral bioavailability. Overall, the solubility, dissolution, and oral bioavailability are consistent with each other. The order of improved solubility, dissolution, and oral bioavailability is observed as consistent like PZQ-SA > PZQ-AA > PZQ-GA > PZQ-OA > PZQ-MA > pure PZQ. Concerning HPC polymer effects, PZQ-OA, PZQ-MA, PZQ-GA, and PZQ-AA co-crystals were formed successfully in the presence of HPC polymer but the PZQ-SA co-crystal was inhibited.

Hydroxypropyl Cellulose for Drug Precipitation Inhibition: From the Potential of Molecular Interactions to Performance Considering Microrheology.

There has been recent interest in using hydroxypropyl cellulose (HPC) for supersaturating drug formulations. This study investigated the potential for molecular HPC interactions with the model drug celecoxib by integrating novel approaches in the field of drug supersaturation analysis. Following an initial polymer characterization study, quantum-chemical calculations and molecular dynamics simulations were complemented with results of inverse gas chromatography and broadband diffusing wave spectroscopy. HPC performance was studied regarding drug solubilization and kinetics of desupersaturation using different grades (i.e., HPC-UL, SSL, SL, and L). The results suggested that the potential contribution of dispersive interactions and hydrogen bonding depended strongly on the absence or presence of the aqueous phase. It was proposed that aggregation of HPC polymer chains provided a complex heterogeneity of molecular environments with more or less excluded water for drug interaction. In precipitation experiments at a low aqueous polymer concentration (i.e., 0.01%, w/w), grades L and SL appeared to sustain drug supersaturation better than SSL and UL. However, UL was particularly effective in drug solubilization at pH 6.8. Thus, a better understanding of drug-polymer interactions is important for formulation development, and polymer blends may be used to harness the combined advantages of individual polymer grades.

Serum Albumin Antifouling Effects of Hydroxypropyl‐Cellulose and Pluronic F127 Adsorbed on Isobutyramide‐Grafted Stellate Silica Nanoparticles

AbstractLimiting the serum protein fouling is a major challenge in the design of nanoparticles (NPs) for nanomedicine applications. Suitable chemical surface modification strategies allow to limit the interactions with adsorbing proteins. In this communication, we address the potential of isobutyramide (IBAM) groups grafted on stellate silica nanoparticles (STMS) for the immobilization of two biocompatible polymers renown for biomedical and low fouling applications: Hydroxypropylcellulose (HPC) and Pluronic F127 (PF127). We report that both polymers can be loaded on STMS@IBAM NPs surface with a maximum loading content close to 10 wt %. Regarding their antifouling properties, we report that the coatings of such HPC or PF127 polymers allow to reduce significantly the human serum albumin (HSA) adsorption in average by 70 % as compared to the surface of the free polymer STMS@IBAM. These results highlight the antifouling potential of these polymer pre‐treatments on IBAM‐modified STMS NPs surface.

Data-Enriched Edible Pharmaceuticals (DEEP) with Bespoke Design, Dose and Drug Release.

Data-enriched edible pharmaceuticals (DEEP) is an approach to obtain personalized medicine, in terms of flexible and precise drug doses, while at the same time containing data, embedded in quick response (QR) codes at a single dosage unit level. The aim of this study was to fabricate DEEP with a patient-tailored dose, modify drug release and design to meet patients’ preferences. It also aimed to investigate physical stability in terms of the readability of QR code patterns of DEEP during storage. Cannabinoids, namely, cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC), were used as the model active pharmaceutical ingredients (APIs). Three different substrates and two colorants for the ink were tested for their suitability to fabricate DEEP by desktop inkjet printing. Flexible doses and customizable designs of DEEP were obtained by manipulating the digital design of the QR code, particularly, by exploring different pattern types, embedded images and the physical size of the QR code pattern. Modification of the release of both APIs from DEEP was achieved by applying a hydroxypropyl cellulose (HPC) polymer coating. The appearance and readability of uncoated and polymer-coated DEEP did not change on storage in cold and dry conditions; however, the HPC polymer layer was insufficient in preserving the readability of the QR code pattern in the extreme storage condition (40 °C and 75% relative humidity). To sum up, the DEEP concept provides opportunities for the personalization of medicines, considering also patients’ preferences.

Design, development and characterisation of a Building Integrated Concentrating Photovoltaic (BICPV) smart window system

Building Integrated Concentrating Photovoltaic (BICPV) window represents a promising alternative approach for improving the electricity generation of photovoltaic cells when integrated into building windows. As a new concept, BICPV smart window consisting of an optically switchable thermotropic layer with integrated PV cells offers the potential to simultaneously generate electricity and control solar heat and visible light into buildings. In this study, a BICPV smart window system with a Hydroxypropyl Cellulose (HPC) based thermotropic hydrogel membrane has been developed and characterised. The system was designed with the aid of a validated wavelength-dependent optical model based on a Monte-Carlo ray-tracing technique, where the thermal and optical properties of the thermotropic layer used for the optical model prediction were obtained from experimental measurement. Subsequently, a prototype of the BICPV smart window system has been fabricated and characterised under controlled indoor conditions. From the experiments, it was found that the maximum power output of the BICPV smart window (6 wt% HPC) increases by 17.1% with the membrane temperature increasing from 40 °C (the transition temperature) to 54 °C; meanwhile, a 70.9% reduction in the light transmittance is observed. This indicated that the BICPC smart window might potentially reduce the solar heat gain in hot periods and therefore reduce the building energy demand. In addition, the effect of different concentrations of HPC polymer (2, 4 and 6 wt%) on the electrical and optical performance of the system has been investigated.

Thermal techniques as a tool for the direction of the preparation of photocatalytically efficient titania thin films and powders

Photocatalytically active titania thin films and powders were prepared via sol–gel route from TiCl4 precursor. Organic polymer hydroxypropyl cellulose was added into sol in order to increase active surface area. Thin films were deposited onto substrates using dip-coating technique. Thin films and xerogels were thermally treated in a muffle furnace to a different extent. Temperature of heat treatment was determined using thermogravimetry and differential scanning calorimetry, while X-ray diffraction was used to identify the formation of the anatase phase, eventual presence of other crystalline formations and the average particle size. The shape and size of the pores of the selected thin films were analyzed using SEM, while specific surface area of selected thermally treated xerogels was determined using Brunauer–Emmett–Teller (BET) surface area analysis. Measurements of photocatalytic efficiency of thin films and powders were performed by FT-IR spectroscopy; for thin films on the basis of diminishing C–H stretching vibrations of model fatty compound methyl stearate during irradiation with UVA light, while in the case of powders the oxidation of isopropanol into acetone was the model photocatalytic reaction. Obtained results confirm that different factors, such as particle size, porosity, thickness of thin film, the presence and type of crystalline titania modification have a substantial effect on photocatalytic efficiency of prepared titania materials.

Roll-to-roll production of Prussian blue/Pt nanocomposite films for flexible gasochromic applications

A high-quality gasochromic (GC) platinum nanoparticle/Prussian blue (PtNP/PB) nanocomposite film was produced for the first time by roll-to-roll (R2R) production for high-throughput processing. Wettability was improved when a small amount of hydroxypropyl cellulose (HPC) was mixed with the PB ink, as confirmed by the decrease in the contact angle from 70.9° to 51.7°.SEM images revealed a significant difference between spin and R2R coating methods and also recognized the change in the morphology due to the HPC polymers. However, because of the non-conductive property of the HPC additive, the PB film resistance and GC performance and stability were also affected by the amount of HPC in the film. The analyses of these characteristics and long-term film stability for 1000 cycles were conducted through in-situ UV–visible spectroscopy and electrochemical cyclic voltammetry.

Droplet Impact Phenomena in Fluidized Bed Coating Process with a Wurster Insert

The aim of this study is to determine favorable process conditions for the coating of placebo tablets. Tablets made of microcrystalline cellulose are coated with hydroxypropyl cellulose polymer and Advantia™ Prime polymeric mixture film in lab-scale fluid-bed environment with a Wurster tube. In order to determine favorable process conditions (concentration, Wurster tube position, inlet air temperature, and atomization pressure), evaluation factors expressing process efficiency were calculated. Stereomicroscopy analysis provided good results with respect to the coating layer adherence and consistency. Results showed that the increased number of the coating cycles contributes to the desired featureless film morphology, when sufficiently high temperature and pressure are applied, thus resulting in high intra- and intertablet uniformity. Additionally, this paper analyzes the coating process from a mechanistic perspective of the underlying phenomena occurring on a tablet surface. Provided diagrams can help efficiently in detecting proper conditions that will result in coated tablets with strictly defined aimed properties. Process and formulation properties synergically result in a preferential occurrence of a deposition mechanism for all experiments conducted. Moreover, collision is found as a prevalent impact regime for the coating process studied. Finally, our intention here is to correlate hydrodynamic conditions and droplet breakup occurrence with a droplet diameter.

Nifedipine di-matrix depot tablets prepared by compression coating for obtaining zero-order release

Compression coating is a possible process for obtaining zero-order release. Nifedipine compression-coated (CC) di-matrix depot tablets were prepared from a single punch tablet press with low viscosity hydroxypropyl cellulose (HPC-L) as the inner polymer, and with middle viscosity hydroxypropyl cellulose (HPC-M), HPC-L and Eudragit RSPO as outer polymers. The release behavior and mechanisms in vitro of the final tablets were investigated, and gravimetric analysis was used to study the release mechanism. The fast release of the core depot and slow release of the outer depot with time formed total zero-order release. The results showed that the formulation presented ideal zero-order release at the weight ratio of nifedipine 3:5 (core: layer), the combination of HPC-L and HPC-M (56:25) in the outer depot, and with the core depot placed in the center. The CC tablets released to more than 95% in 24 h and fitted a zero-order model with the equation Mt/M∞ = 0.038t (R2 = 0.98555). In conclusion, zero-order release of nifedipine over 24 h could be achieved by applying polymer HPC-L and HPC-M with the compression coating technique.

Optimization and evaluation of mucoadhesive buccal films loaded with resveratrol

Resveratrol, a phytoalexin from grapes, has shown several therapeutic benefits such as anti-inflammatory and chemopreventive effects. There is a need to develop novel methods for delivery of resveratrol since it poses problems such as high first pass metabolism and therefore low oral bioavailability. Drug delivery through buccal mucosa offers novel approach in circumventing hepatic metabolism and providing controlled drug release with a wide scope for application for local or systemic deliveries. The present investigation deals with optimization and evaluation of mucoadhesive buccal films of resveratrol. The mucoadhesive buccal films of resveratrol were prepared by solvent casting method using polymer Hydroxypropyl cellulose (HPC) and Ethyl cellulose (EC). Optimization was achieved using 32 full factorial design whereby the effect of HPC (X1) and EC (X2) concentrations on mucoadhesive strength (Y1), swelling (Y2) and in vitro drug release (Y3) profile were analyzed. The resulting films were characterized for weight uniformity, thickness, folding endurance, drug content, surface pH, swelling, mucoadhesive strength and in vitro drug release. The optimized formulation comprised of 2% (w/v) HPC and 1% (w/v) EC, exhibited satisfactory mucodhesive strength, swelling and optimum drug release upto 8 h. Histopathology of buccal mucosa treated with optimized buccal films exhibited no signs of mucosal damage.

Confinement Effects on Polymer Dynamics: Thermo-Responsive Behaviours of Hydroxypropyl Cellulose Polymers in Phospholipid-Coated Droplets (Water-in-Oil Emulsion).

In order to construct the artificial cells and to understand the physicochemical properties of living cells, it is important to clarify the cell-sized confinement effect on the behaviours of bio-inspired polymers. We report the dynamic behaviours of aqueous hydroxypropyl cellulose (HPC) solution coated with phospholipids in oil (water-in-oil droplets, W/O droplets), accompanied by an increase in the temperature. We directly observed the beginning of phase separation of HPC solution using a fluorescence microscope and confirmed the dependence of such phenomena on droplet size. The results indicate that the start time of phase separation is decreased with an increase in droplet size. The experimental results suggest that the confinement situation accelerates the phase separation of aqueous HPC solutions.

Ionic polymer enhanced electrophoresis in plastic microchips for rapid and robust determination of rhodamine dyes

Electrophoresis on plastic microchips is an economic way for rapid separation and determination of multiple analytes, but its application is frequently limited by the unstable electroosmotic flow (EOF) and non-specific adsorption of certain analytes and sample matrices. In this work, cationic polymer poly (diallyldimethylammonium chloride) (PDDA) was used as the background electrolyte (BGE) to eliminate the non-specific adsorption, control the EOF, regulate the viscosity and improve the separation efficiency on cyclic olefin copolymer microchips with 75μm id microchannels. Three rhodamine dyes that are easily adsorbed on plastics were separated in the presence of organic solvents. Influences of the experimental conditions were systematically investigated and the performance was compared with anionic polymer polyacrylic acid or neutral polymer hydroxypropyl cellulose. The effectiveness of ionic polymers for the modulation of EOF was demonstrated. With PDDA as BGE, three rhodamine dyes were well separated and baseline separation could be achieved in 20s with a voltage as low as 400V using a microchannel of 1cm long and 75μm id. The determination of rhodamine dyes in foods and lipsticks was performed to verify the robustness and applicability of the proposed methods. Separation of peptides and proteins labeled by rhodamine B isothiocyanate was also performed with the proposed running medium.

The development of sustained release drug delivery platforms using melt-extruded cellulose-based polymer blends.

This research examined the application of hot melt extrusion (HME) in the preparation of matrix formulations containing hydroxypropyl cellulose (HPC) as a base polymer in combination with methyl cellulose (MC) and hydroxypropyl methylcellulose (HPMC). The limit to which formulations could control drug release under varying paddle speeds, high alcohol environments and high and low drug loads was investigated on a Caleva 10 ST dissolution tester. Rheological studies and hot plate imaging highlighted the impact of thermoresponsive polymers on drug release. The rate and percentage release of drug were analysed using a one-way ANOVA and Tukey's HSD test. No significant differences in the amount of drug released were calculated as a result of paddle speed variation or in the presence of 40% v/v ETOH. The phase separation effects of temperature-sensitive polymers HPC and MC and the characteristic gel shrinkage and fluid expulsion were shown to be contributing factors. The use of the partition activity, α, identified the extent to which formulations were affected by phase separation. Hot melt extrusion was successfully used to manufacture cellulose-based formulations. Thermoresponsive polymers HPC and MC significantly impacted drug release properties.