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.

Controlled release formulations offer many advantages over conventional dosage forms. These include reduced plasma fluctuations and improved patient comp1i:nce. Complex controlled release formulations such as those with enteric release properties, often require additional steps in the production phase. The costs and economic impact associated with these complex controlled release dosage formulations often outweigh the immediate benefits. Thus the development of an economic method to produce controlled release particles is of great importance especially in third world countries. In controlled release formulations, the drug is generally dispersed throughout a polymer matrix. The rate of drug release is often determined by the viscosity or complexity of the polymer matrix through which the drug needs to diffuse in order to be released. With enteric release the polymer coating, insoluble in an acidic environment is often applied in the final phase of production. Chitosan is a versatile polymer of natural origin with many favourable characteristics. These include its safety, biocompatibility, and biodegradability. Simple methods can be applied and modified to produce controlled release particles form chitosan. The effect of modern controlled release polymers such as Aqoat AS-HF, Eudragit SlOO and Kollidon SR was investigated. Chitosan beads and chitosan-polymer beads, as well as chitosan granules and chitosan-polymer granules, were prepared and investigated as possible controlled release formulations. Ketoprofen was chosen as the model drug. Chitosan beads and chitosan-polymer beads were prepared by inotropic gelation in tripolyphosphate. Chitosan granules and chitosan-polymer matrix granules were prepared by binding chitosan with an acetic acid solution as a granulating system. The beads and granules appeared differed in appearance as well as in the results obtained from various experiments. Granules prepared in the study did not appear to be effective with regards to enteric and controlled release. Beads prepared form Kollidon SR appeared to be effective with regards to enteric and controlled release, with Kollidon 1% and 5% w/v chitosan beads achieving good drug loading of up to 73.13% and releasing less than 15 % of the total drug content in 0.1 M HCI after 60 minutes. Drug release continued steadily for up to 360 minutes in pH 7.2. It was concluded that Kollidon SR loaded chitosan beads nay be a viable controlled release dosage form with enteric release properties, and that future experiments, possibly with lower polymer concentrations, are worthwhile / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2006.

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.

Cellulose is one of the most abundant biopolymers found in nature. Cellulose based derivatives have a number of advantages including recyclability, reproducibility, biocompatibility, biodegradability, cost effectiveness and availability in a wide variety of forms. Due to the benefits of cellulose based systems, this research study was aimed at developing novel cellulosic nanoparticles with potential pharmaceutical and personal care applications. Two different cellulosic systems were evaluated, each with its own benefits and proposed applications. The first project involves the synthesis and characterization of polyampholyte nanoparticles composed of chitosan and carboxymethyl cellulose (CMC), a cellulosic ether. EDC carbodiimide chemistry and inverse microemulsion technique was used to produce crosslinked nanoparticles. Chitosan and carboxymethyl cellulose provide amine and carboxylic acid functionality to the nanoparticles thereby making them pH responsive. Chitosan and carboxymethyl cellulose also make the nanoparticles biodegradable and biocompatible, making them suitable candidates for pharmaceutical applications. The synthesis was then extended to chitosan and modified methyl cellulose microgel system. The prime reason for using methyl cellulose was to introduce thermo-responsive characteristics to the microgel system. Methyl cellulose was modified by carboxymethylation to introduce carboxylic acid functionality, and the chitosan-modified methyl cellulose microgel system was found to be pH as well as temperature responsive. Several techniques were used to characterize the two microgel systems, for e.g. potentiometric and conductometric titrations, dynamic light scattering and zeta potential measurements. FTIR along with potentiometric and conductometric titration was used to confirm the carboxymethylation of methyl cellulose. For both systems, polyampholytic behaviour was observed in a pH range of 4-9. The microgels showed swelling at low and high pH values and deswelling at isoelectric point (IEP). Zeta potential values confirmed the presence of positive charges on the microgel at low pH, negative charges at high pH and neutral charge at the IEP. For chitosan-modified methyl cellulose microgel system, temperature dependent behaviour was observed with dynamic light scattering. The second research project involved the study of binding interaction between nanocrystalline cellulose (NCC) and an oppositely charged surfactant tetradecyl trimethyl ammonium bromide (TTAB). NCC is a crystalline form of cellulose obtained from natural sources like wood, cotton or animal sources. These rodlike nanocrystals prepared by acid hydrolysis of native cellulose possess negatively charged surface. The interaction between negatively charged NCC and cationic TTAB surfactant was examined and it was observed that in the presence of TTAB, aqueous suspensions of NCC became unstable and phase separated. A study of this kind is imperative since NCC suspensions are proposed to be used in personal care applications (such as shampoos and conditioners) which also consist of surfactant formulations. Therefore, NCC suspensions would not be useful for applications that employ an oppositely charged surfactant. In order to prevent destabilization, poly (ethylene glycol) methacrylate (PEGMA) chains were grafted on the NCC surface to prevent the phase separation in presence of a cationic surfactant. Grafting was carried out using the free radical approach. The NCC-TTAB polymer surfactant interactions were studied via isothermal titration calorimetry (ITC), surface tensiometry, conductivity measurements, phase separation and zeta potential measurements. The major forces involve in these systems are electrostatic and hydrophobic interactions. ITC and surface tension results confirmed two kinds of interactions: (i) electrostatically driven NCC-TTAB complexes formed in the bulk and at the interface and (ii) hydrophobically driven TTAB micellization on the NCC rods. Conductivity and surface tension results confirmed that the critical micelle concentration of TTAB (CMCTTAB) shifted to higher values in the presence of NCC. Phase separation measurements allowed us to identify the formation of large aggregates or hydrophobic flocs depending on the TTAB concentration. Formation of NCC-TTAB complexes in aqueous solutions was confirmed by a charge reversal from negative to positive charge on the NCC rods. The effect of electrolyte in shielding the negative charges on the NCC was observed from ITC, surface tensiometry and phase separation experiments. Several mechanisms have been proposed to explain the above results. Grafting of PEGMA on the NCC surface was confirmed using FTIR and ITC experiments. In phase separation experiments NCC-g-PEGMA samples showed greater stability in the presence of TTAB compared to unmodified NCC. By comparing ITC and phase separation results, an optimum grafting ratio (PEGMA : NCC) for steric stabilization was also proposed.

Chitin is a polysaccharide found in abundance in the shell of crustaceans. In this study, chitin was first extracted from shrimp waste material previously demineralized, using proteolytic enzymes, i.e., chymotrypsin and papain. The conditions used for the deproteinization were optimized with respect to 3 factors, viz., pH, temperature, and enzyme to waste (E/W) ratio, using response surface methodology (RSM). / In a second part of the study, chitosan was prepared from chitin by partial deacetylation and its capacity to preserve whole and headless fresh shrimps was evaluated. The shrimps (Pandalus borealis) were dipped in chitosan (1 and 2% w:v), and stored on ice. Chemical indicators such as pH, drip loss, total volatile bases (TVB), nucleotide degradation, and sensory indicators of appearance (including melanosis) and odor, as well as total microbial counts were monitored during 20 days. / As a third and final part, the antimicrobial properties of chitosan were evaluated using several microorganisms implicated in food spoilage and/or food poisoning outbreaks, especially those associated with fish and seafood products. Chitosan prepared from crab offal and used in the previous study on shrimp preservation was compared with commercially available chitosan from Sigma Chemical Co. (St-Louis, MO). (Abstract shortened by UMI.)

Kentucky reported a solid 13.1% growth in certified organic land from 1997 to 2002. The relative lack of research on disease management practices in Kentucky consistent with organic regulations is an issue that needs to be addressed to provide more reliable information to local farmers. Thus, the first objective of this research was to investigate the potential disease control obtained with natural, organically certifiable spray materials against Colletotrichum orbiculare in vitro and in vivo. The second objective was to test certifiable spray materials in combinations to identify synergistic interactions. The third objective was to evaluate Organic Material Review Institute (OMRI)-certified materials for managing Septoria leaf spot and early blight in tomato under field conditions. The fourth objective was to evaluate chitosan-based products against C. orbiculare in vitro and in vivo. Essential oils, Trilogy®, and Actinovate®, failed to suppress C. orbiculare in vitro as well as cucurbit anthracnose. Bicarbonate salts, Regalia®SC, Sonata®, copper based-products, lime sulfur and water-soluble chitosan showed high antifungal activity in vitro. Bicarbonate salts, Sonata®, Serenade Max®, Soil Gard 12G®, copper based-products and lime sulfur reduced anthracnose disease severity in vivo. In the synergism experiments only a limited number of mixtures showed synergistic interactions, but even in those cases, the effect was not consistent between experiments. The main response obtained was antagonism. In field experiments the most effective fungicides for managing Septoria leaf spot and early blight of tomato were copper-based fungicides. None of the biological-based products (Sonata® and Serenade Max®)), plant-based extracts (Trilogy® and Regalia® SC), chitosan, ammonium bicarbonate nor horticultural lime sulfur provided a significant reduction in disease severity. For the fourth objective, water-soluble chitosan with a molecular weight between 3 to 10 kDa (80 and 85% deacetylated) showed the highest antifungal activity among all chitosan-based products evaluated in vitro. Also, combining the in vitro and in vivo results suggest that the antifungal activity of chitosan-based products is molecular weight- and concentration-dependent. These results provide a significant advance in the evaluation of the efficacy of OMRI-certified materials and natural materials to help organic farmers in Kentucky and the USA to manage diseases.

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.