We have developed CO2-selective membranes to purified hydrogen and nitrogenfor fuel cell processes. Hydrogen purification impacts other industries such as ammoniaproduction and flue gas purification at reduced costs.Dense chitosan membranes were used for the first time to separate CO2 from amixture of 10% CO2, 10% H2, and 80% N2 at temperatures of 20 – 150oC and feedpressures of 1.5 atm – 5 atm. At 1.5 atm and 20 – 150oC, dry chitosan membranesachieved CO2 permeabilities, CO2/N2 and CO2/H2 separation factors of 0.383 – 24.3barrers, 10.7 – 3.40, and 4.54 – 1.50, respectively. The dry chitosan acted as an ordinarysolution-diffusion membrane: permeability increased with temperature but selectivitydecreased. The CO2/H2 and CO2/N2 separation factors at all temperatures enhanced CO2removal, making this membrane a candidate for fuel cell processes. The dual modetransport model fitted the transport data well.To achieve higher CO2 transport properties, chitosan was swollen with water.Water mediated the reaction of chitosan's amino groups with CO2. Humidifing the feedand sweep gases increased the membrane's performance. At 1.5 atm and 20 – 110 –150oC, CO2 permeabilities, CO2/N2 and CO2/H2 separation factors were 213 – 483 – 399barrers, 69.4 – 250 – 194, and 18.9 – 43.4 – 29, respectively. The presence of free waterand bound water facilitated the transport of CO2. Increasing feed pressure removed themaxima in permeability and selectivities at 110oC, but led to reduced CO2 permeabilities,CO2/N2 separation factors, and CO2/H2 separation factors to 156 – 286 barrers, 44.2 –131, and 12.0 – 16.7, respectively.To acquire higher CO2 transport properties, arginine-sodium salts wereincorporated in chitosan membranes as additional sites for facilitated transport. The salt'spercolation threshold was 40 wt %. At 1.5 atm and 20 – 110 – 150oC, CO2 permeabilities,CO2/N2 and CO2/H2 separation factors were 403 – 1498 – 1284 barrers, 122 – 852 – 516,and 31.9 – 144 – 75.5, respectively. Increasing feed pressure to 5 atm resulted indeclining CO2 permeabilities, CO2/N2 and CO2/H2 separation factors to 118 – 1078barrers, 21.6 – 352, and 5.67 – 47.9, respectively.Chitosan was characterized in terms of morphology, solution properties, thermalproperties, crystallinity, and degree of deacetylation.

Nanoparticles have received special attention over past few years as potential drug carriers for proteins/peptides and genes. Biodegradable polymeric poly (lactic-co-glycolic acid) (PLGA) nanoparticles are being employed as non-viral gene delivery systems for DNA. This work demonstrates a scalable technology for synthesis of nanoparticles capable of gene delivery. Cationic PLGA nanoparticles are produced by emulsiondiffusion- evaporation technique employing polyvinyl alcohol (PVA) as stabilizer and chitosan chloride for surface modification. A sonicator is used for the emulsion step and a static mixer is used for dilution in the diffusion step of the synthesis. A static mixer is considered ideal for the synthesis of PLGA nanoparticles as it is easily scalable to industrial production. The resulting nanoparticles are spherical in shape with size in the range of 100–250 nm and posses a zeta potential above +30 mV, indicating good stability of the colloid with a positive charge to bind to anionic DNA. The mechanism of nanoparticle formation was analyzed using multimodal size distributions (MSD), zeta potential data, and transmission electron microscopy (TEM) images. Several emulsion techniques and dilution effect were analyzed in this work. PVA acts as a compatibilizer for chitosan chloride and dilution of primary emulsion has little effect over the particle size of the PLGA nanoparticles.

The purpose of this research project was to develop and characterise matrix type microspheres prepared from Eudragit® L100, containing insulin as model peptide drug as well as an absorption enhancer, N-trimethyl chitosan chloride (TMC), to improve intestinal absorption via the paracellular route. Insulin loaded microspheres were prepared using a single water in oil emulsification/evaporation method in accordance with a fractional factorial design (23) and subsequently characterised in terms of morphology as well as internal structure. Also, insulin and TMC loading were determined using a high pressure liquid chromatography analysis (HPLC) and colorimetric assay, respectively. Scanning electron microscopic characterisation revealed that most microsphere formulations showed a spherical shape and smooth surface with a sponge-like internal structure as well as relatively good homogeneity in terms of size distribution. Insulin loading ranged from 27.9 ± 14.25 – 52.4 ± 2.72% between the different formulations. TMC loading was lower than for insulin and ranged from 29.1 ± 3.3 - 37.7 ± 2.3% between the different formulations. The pronounced difference in insulin and TMC loading between the microsphere formulations is probably the result of the multitude parameters involved as well as the complex physicochemical processes which govern emulsification/solvent evaporation. Based on the microsphere characterisation results, two formulations were selected (i.e. B and F) for further characterisation (i.e. particle size distribution, dissolution behaviour, and enteric nature) and for in vitro evaluation of insulin transport across excised Fischer (FSR) rat intestinal tissue using a Sweetana-Grass diffusion chamber. Particle size analysis by means of laser light diffraction of the two selected microsphere formulations revealed that the mean particle size (based on volume) ranged from 135.7 ± 41.05 to 157.3 ± 31.74 m. Dissolution results for microsphere Formulations B and F revealed that both insulin and TMC were released from the microsphere formulations in an alkaline environment (pH 7.4). The mean dissolution time (MDT) for insulin ranged from 34.5 ± 4.01 to 42.6 ± 9.06 min, while the MDT for TMC ranged from 1.2 ± 1.73 to 6.8 ± 6.42 min. Statistical analysis revealed no significant differences in the MDT of either insulin or TMC (p-value > 0.05) between the two formulations, although the difference between insulin and TMC of each formulation was significant (p-value < 0.05). Microsphere formulations B and F released 36.92 and 48.21% of their total drug content over a period of 1 h in 0.1 M HCl. Microsphere Formulation B showed 8.3 ± 0.52% and formulation F 8.9 ± 2.26% transport of the initial insulin dose after a period of 120 min across excised rat intestinal tissue. The increase in insulin transport by the microsphere formulations compared to that of the control group (i.e. insulin alone) correlated well with the decrease in transepithelial electrical resistance (TEER) caused by the microsphere formulations. The transport of insulin from Formulations B and F represented transport enhancement ratios of 10.67 and 9.68, respectively. Insulin loaded EudragitL100 microspheres containing TMC were successfully prepared by emulsification/solvent evaporation that demonstrated promising potential to serve as oral drug delivery systems for insulin. The microspheres exhibited improved insulin permeability across intestinal epithelial tissue; however, its enteric properties should be improved and clinical effectiveness need to be confirmed by future in vivo studies. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

The purpose of this research project was to develop and characterise matrix type microspheres prepared from Eudragit® L100, containing insulin as model peptide drug as well as an absorption enhancer, N-trimethyl chitosan chloride (TMC), to improve intestinal absorption via the paracellular route. Insulin loaded microspheres were prepared using a single water in oil emulsification/evaporation method in accordance with a fractional factorial design (23) and subsequently characterised in terms of morphology as well as internal structure. Also, insulin and TMC loading were determined using a high pressure liquid chromatography analysis (HPLC) and colorimetric assay, respectively. Scanning electron microscopic characterisation revealed that most microsphere formulations showed a spherical shape and smooth surface with a sponge-like internal structure as well as relatively good homogeneity in terms of size distribution. Insulin loading ranged from 27.9 ± 14.25 – 52.4 ± 2.72% between the different formulations. TMC loading was lower than for insulin and ranged from 29.1 ± 3.3 - 37.7 ± 2.3% between the different formulations. The pronounced difference in insulin and TMC loading between the microsphere formulations is probably the result of the multitude parameters involved as well as the complex physicochemical processes which govern emulsification/solvent evaporation. Based on the microsphere characterisation results, two formulations were selected (i.e. B and F) for further characterisation (i.e. particle size distribution, dissolution behaviour, and enteric nature) and for in vitro evaluation of insulin transport across excised Fischer (FSR) rat intestinal tissue using a Sweetana-Grass diffusion chamber. Particle size analysis by means of laser light diffraction of the two selected microsphere formulations revealed that the mean particle size (based on volume) ranged from 135.7 ± 41.05 to 157.3 ± 31.74 m. Dissolution results for microsphere Formulations B and F revealed that both insulin and TMC were released from the microsphere formulations in an alkaline environment (pH 7.4). The mean dissolution time (MDT) for insulin ranged from 34.5 ± 4.01 to 42.6 ± 9.06 min, while the MDT for TMC ranged from 1.2 ± 1.73 to 6.8 ± 6.42 min. Statistical analysis revealed no significant differences in the MDT of either insulin or TMC (p-value > 0.05) between the two formulations, although the difference between insulin and TMC of each formulation was significant (p-value < 0.05). Microsphere formulations B and F released 36.92 and 48.21% of their total drug content over a period of 1 h in 0.1 M HCl. Microsphere Formulation B showed 8.3 ± 0.52% and formulation F 8.9 ± 2.26% transport of the initial insulin dose after a period of 120 min across excised rat intestinal tissue. The increase in insulin transport by the microsphere formulations compared to that of the control group (i.e. insulin alone) correlated well with the decrease in transepithelial electrical resistance (TEER) caused by the microsphere formulations. The transport of insulin from Formulations B and F represented transport enhancement ratios of 10.67 and 9.68, respectively. Insulin loaded EudragitL100 microspheres containing TMC were successfully prepared by emulsification/solvent evaporation that demonstrated promising potential to serve as oral drug delivery systems for insulin. The microspheres exhibited improved insulin permeability across intestinal epithelial tissue; however, its enteric properties should be improved and clinical effectiveness need to be confirmed by future in vivo studies. / Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

Chitosan membrane has found applications in biomedical, wastewater treatment, and petrochemical fields that involve the use of silver ions (Ag+). However, mobility of Ag+ in chitosan membranes has seldom been studied. In this study, transport properties of Ag+ in chitosan membranes are studied in-depth, to determine diffusivity coefficient, permeability coefficient, and sorption uptake of Ag+ in chitosan. All parameters are evaluated based on the influence of feed concentration, membrane thickness and operating temperature. The diffusivity is determined from the time lag obtained from transient diffusion experiments. The permeability is determined from the steady state of permeation experimentally. The diffusivity and corresponding permeability coefficients of Ag+ in chitosan range from to 2.0 10-7 (cm2/s) and from 6.6 10-8 to 2.0 10-7 {mol m/[m2 s (mol/L)]}, respectively, over the conditions tested. Temperature dependencies of these two parameters are found to follow the Arrhenius relationship. Sorption uptake of the silver salt in chitosan correlates well with the Langmuir isotherm. Also determined from the sorption tests are degree of membrane swelling at different concentrations. This information allows diffusivity coefficients to be determined from the steady state permeation rate. These values of diffusivity are compared with that obtained using the time lag method.

Chitosan has proven through the years as a versatile biomaterial to be used in pharmaceutical applications. Its mucoadhesive properties as well as its ability to manipulate the tight junctions in epithelium membranes have qualified it as an effective drug carrier in controlled drug delivery systems. Microparticles or beads as they are forward called in this study have advantages over conventional drug dosage forms because of a large surface to volume ratio and have the ability to target a specific site for drug release. Indomethacin is an anti-inflammatory drug that causes gastrointestinal side effects in conventional immediate-release dosage forms. The goal is to manipulate the drug delivery vehicle to target the intestines/colon as the site for drug delivery and to minimize this side effect. Thus chitosan beads have been chosen as a drug delivery system for indomethacin in this study. Chitosan beads have been prepared through the ionotropic gelation method using tripolyphophate (TPP) as a cross-linking agent. To prepare the most effective bead to encapsulate indomethacin different formulation and system variables (pH of the TPP solution, the concentration of the TPP solution as well as the indomethacin concentration) have been evaluated according to the following parameters: morphology, drug loading capacity and swelling capability. The ideal pH of the TPP solution was determined at 8.7 and the most effective TPP and indomethacin concentration were 5% w/v and 4% w/v respectively. The chitosan concentration was kept at 3% w/v throughout the study. These concentrations were used to examine the effect of pharmaceutical excipients on the indomethacin release from chitosan beads. The effect of the different excipients namely, ExplotabⒽ(0.25% w/v), Ac-Di-SolⓀ (0.5% w/v) and Vitamin C (0.25% w/v), on the morphology, drug loading capacity, swelling capability as well as the drug release of indomethacin chitosan beads (ICB's) were also studied. The excipients were used in the individually above mentioned concentrations and in combination with each other in the same concentrations. These formulations were used in dissolution studies over a period of 6 hours in PBS pH 7.4 solutions. The indomethacin release rate increased when an excipient was added to the formulation and it dramatically increased when the excipients were added in their various combinations, compared to the formulation that did not contain excipients. / Contents: Chitosan -- Controlled drug delivery -- Indomethacin -- Inotropic gelation -- Tripolyphosphate (TPP) -- Explotab® -- Ac-Di-Sol® -- Vitamin C / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.

Controlled release systems aim at achieving a predictable and reproducible drug release over a desired time period. These systems allow reduced dosing frequency, constant drug levels in the blood, increased patient compliance and decreased adverse effects. In a recent study, Chitosan beads, containing N-trimethyl Chitosan chloride, have shown a potential in the delivery of rifampicin. However, because of inadequate amounts of rifampicin released over 24 hours, incorporation of other pharmaceutical excipients to increase the swelling behaviour of the beads to improve drug release, was considered in this study. Chitosan beads were prepared through ionotropic gelation with tripolyphosphate (TPP) as a crosslinking agent. To increase the porosity if the Chitosan beads Explotab®, Ac-Di-Sol® and vitamin C were added individually to Chitosan solutions at concentrations of 0.1, 0.25 and 0.5 % w/v before adding the mixture to the TPP solution. Swelling and morphology studies were used in the evaluation of the different formulations. The swelling and morphology results were then used to select a set of combination and concentrations of two excipients sand then prepare and characterise beads containing two combinations. The combination formulations and formulations containing single excipients were then loaded with rifampicin. Pure chitosan beads exhibited a higher drug loading capacity (67.49 %) compared to the lowest loading capacity of 41.61 % exhibited by chitosan beads containing a combination of Explotab®, Ac-Di-Sol®.For all the other formulations the drug loading capacity ranged within 48 and 63 %. These formulations were used for dissolution studies over a period of 6 hours at pH 5.60 and 7.40. The dissolution results showed that no chitosan has dissolved at both pH values. A significant amount of rifampicin was, however, released from the beads, especially at pH 7.40. chitosan beads containing vitamin C also exhibited high rifampicin release (48.34 ± 1.00) %) at pH 5.60 compared to the other formulations and this makes vitamin C a potential excipient for enhanced drug release over a wide pH range (both acidic and alkalinic). However, further studies are necessary to optimise the preparation method to minimise drug loss during loading and to improve the drug loading capacity of the beads. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2005.

Approximately 350 million people worldwide suffer from diabetes mellitus (DM) and this number increases yearly. Since the discovery and clinical application of insulin in 1921, subcutaneous injections have been the standard treatment for DM. Because insulin is hydrophilic and has a high molecular weight and low bioavailability, this molecule is poorly absorbed if administered orally. The aim of this study is to evaluate nasal delivery systems for insulin, using Sprague Dawley rats as the nasal absorption model. Pheroid technology and N-trimethyl chitosan chloride (TMC) with different dosages of insulin (4, 8 and 12 IU/kg bodyweight insulin) was administered in the left nostril of the rat by using a micropipette. Pheroid technology is a patented (North-West University) carrier system consisting of a unique oil/water emulsion that actively transports drug actives through various physiological barriers. These formulations were administered nasally to rats in a volume of 100 p/kg bodyweight in different types of Pheroids (vesicles, with a size of 1.7 1 - 1.94 pm and microsponges, with a size of 5.7 1 - 8.25 pm). The systemic absorption of insulin was monitored by measuring arterial blood glucose levels over a period of 3 hours. The TMC formulation with 4 IU/kg insulin produced clinically relevant levels of insulin in the blood and as a result also the maximal hypoglycaemic effect. TMC is a quaternary derivative of chitosan and is able to enhance the absorption of various peptide drugs by opening tight junctions between epithelial cells. Pheroid formulations were also effective in lowering blood glucose levels but only at higher doses (8 and 12 IU/kg) of insulin. This study indicated that Pheroid rnicrosponges had a faster onset of action and a slightly better absorption of insulin when compared to Pheroid vesicles, but many more studies are needed in this field. Although the results of this study with absorption enhancers are encouraging, nasal insulin bioavailability is still very low, and the Pheroid formulations and long-term safety of nasal insulin therapy have yet to be investigated. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.

Advances in biotechnology and recombinant technologies have lead to the production of several classes of new drugs such as peptide and protein drugs. These compounds are mostly indicated for chronic use but their inherent characteristics such as size, polarity and stability prevent them from incorporation in novel dosage forms. The bioavailability of nearly all peptide drugs is very low due to poor absorption from the administration site. Several challenges confront the pharmaceutical scientist in developing effective and innovative dosage forms for these classes of drugs. A lot of attention has been given to the nasal route of drug administration for delivery of peptide drugs. The availability of several promising classes of absorption enhancers and new drug delivery technologies has also prompt scientists to develop new delivery systems for nasal administration of peptide drugs. It has been shown in recent years that N-trimethyl chitosan chloride (TMC), a quaternary derivative of chitosan, is effective in enhancing the absorption of several peptide drugs, both in the peroral route and in the nasal route of drug administration. Early indications are that new drug delivery technologies such as Pheroid technology will also be able to enhance peptide drug absorption in the nasal route. The aim of this study was to evaluate and compare the absorption enhancing abilities of TMC and Pheroid technology in the nasal delivery of calcitonin, a peptide hormone with low bioavailability. Pheroid vesicles and Pheroid microsponges were prepared and characterized for their morphology and size distribution. Calcitonin was entrapped into these vesicles and microsponges and TMC and TMO solutions (0.5 % w/v), containing calcitonin, was also prepared. These formulations were administered nasally to rats in a volume of 100 μl/kg body-weight to obtain a final concentration of 10 IU/kg body-weight of calcitonin. Plasma calcitonin and calcium levels were determined over a period of 3 hours. The results of this study clearly indicated that both Pheroid formulations and the TMC formulation increase the nasal absorption of calcitonin with a resulting decrease in plasma calcium levels, indicating an increased absorption of calcitonin. The highest increase in calcitonin absorption was obtained with the TMC formulation and this was explained by the difference in the mechanism of action in enhancing peptide absorption between TMC and Pheroid technology. It was concluded that Pheroid technology is also a potent system to enhance peptide drug delivery and that the exact mechanism of action should be investigated further. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2006.

The absorption enhancing ability of chitosan, a linear polysaccharide, is mediated by protonated amino groups on the C-2 position of the molecules that induce interaction with the anionic sites on the cell membranes to subsequently alter tight junction integrity. In neutral and basic environments, such as those found in the small and large intestines, most chitosan molecules will lose their charge and precipitate from solution rendering it ineffective as an absorption enhancer. To increase the solubility of this polymer, methylation of the amino groups on the C- 2 position was proposed. A partially quaternised and water soluble derivative of chitosan, N-trimethyl chitosan chloride (TMC), which exhibits superior solubility in a basic environment compared with other chitosan salts was synthesised and included in a chitosan microbead solid drug delivery system. Two TMC derivatives were synthesised by reductive methylation from high and medium molecular weight Chitoclear™ chitosan respectively. The degree of quaternisation calculated from the 1H-NMR spectra for the medium molecular weight TMC (TMC-M) and the high molecular weight TMC (TMC-H) polymers were 74.7 % and 48.5 % respectively. The mean molecular weights of the synthesised TMC-M and TMC-H polymers were 64 100 g/mole and 233 700 g/mole respectively. The effect of different concentrations TMC-M and TMC-H on chitosan microbeads was studied with results obtained from scanning electron microscopy (SEM), TMC loading capacity and microbead swelling behaviour. After selection of the most suitable TMC concentration, the effect of varying concentration (0.1, 0.2 and 0.5 %) additives on TMC and ibuprofen release was studied. Commonly used modified cellulose gum (Ac-di-sol®(ADS)), sodium starch glycolate (Explotab®(EXP)) and ascorbic acid (AA) were added as disintegrants to different microbead formulations to promote release of both the ibuprofen as model drug and TMC from the beads. It was noticed that the loading (% drug loading capacity) of TMC-M was much lower than that obtained with TMC-H while the inclusion of different additives in varying concentrations did not seem to have a profound influence on the loading of either TMC-M or TMC-H. It was further noticed from the fit factors (f1 and f2) for dissolution profiles of eighteen chitosan microbead variations that the formulation containing TMC-H and 0.5% (w/v) ascorbic acid was the only formulation with a significantly higher ibuprofen and TMC-H release profile compared to all other formulations tested. The chitosan microbead formulation containing 2%(w/v) TMC-H and 0.5 % (w/v) ascorbic acid (H-AA-0.5) was used for in vitro absorption studies through rat intestine in Sweetana-Grass diffusion chambers. Chitosan containing TMC-H (no ascorbic acid) (CHIT-H) only and a plain chitosan microbead (CHIT) formulation was used as control formulations during the in vitro studies. Although the H-AA-0.5 formulation exhibited the highest transport rate for ibuprofen, the mean rate of transport (P app) obtained from the two formulations containing TMCH (CHIT-H and H-AA-0.5) showed no significant difference in the transport rate of ibuprofen. Compared to the CHlT formulation as control, both formulations containing TMC-H exhibited increased ibuprofen transport across in vitro rat jejunum. However, a statistical significant increase in transport was obtained only from the H-AA-0.5 formulation in comparison with the CHlT formulation. It can be concluded that the combination of high molecular weight TMC with a low degree of quaternisation and ascorbic acid (0.5% w/v) in a chitosan microbead lead to a statistical significant increase in the in vitro transport rate of ibuprofen through rat jejunum. / Thesis (Ph.D. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2006.