Development of a chitosan based glucose responsive nanoparticulate insulin delivery system

Research into responsive polymeric insulin delivery systems for the management of diabetes mellitus is gaining increasing interest due to the rise in the incidence rate and the burden of daily multiple subcutaneous insulin injections that needs to be endured by the patient. The present study attempted to formulate a nanoparticulate glucose responsive insulin delivery system from a natural polymer chitosan, using a safe glucose sensor, phenyl boronic acid (PBA), which is known to interact with glucose. In the present project, a new method for the production of chitosan tripolyphosphate (TPP) nanoparticles via ultrasonication was developed and optimised. The electrostatic method of tagging PBA onto chitosan was unsuccessful, but the method of N-reductive alkylation of introducing the PBA was successful. Evidence of PBA bonding on to chitosan was assessed by FTIR, ToF-SIMS, DSC and glucose adsorption sensitivity measurements. Glucose adsorption sensitivity to PBA-bonded chitosan polymer was directly related to the amount of PBA functionality within the conjugates and the physical nature of the matrices (porous or crystalline) as revealed by scanning electron microscopy (SEM). The nanoparticles showed glucose concentration dependent swelling with swelling decrease at a glucose concentration above 2.5mg/ml. Encapsulation of insulin into the nanoparticulate matrix was achieved by both the ionotropic gelation and polyelectrolyte complexation methods. Smaller particles with z-average between 140 – 150nm, lower Pdi and zeta potential between 17.5-19.1mV were characteristic of particles produced by PEC, whilst slightly larger particles with z-averages between 170-200nm, higher Pdi and zeta potential between +17.6-21.6mV were noticed for the particles produced by ionotropic gelation. Higher encapsulation of insulin of about 90% was achieved using the PEC method as compared to 34% from the ionotropic gelation series. The amount of drug encapsulated in both methods was pH dependent. In vitro xxi glucose dependent insulin release studied on PEC formulations showed a glucose and fructose concentration dependent release which was affected by the buffer system used. Lower insulin release from higher concentration of the sugars was attributed to the formation of bidentate interaction between the diols in the sugar and PBA, which restricts further expansion of the nanoparticles and hence reduces insulin release. This was confirmed by the SEM images of the nanoparticles after exposure to buffer, glucose and fructose in buffers at pH 7.4. Nanoparticles exposed to fructose showed more spherical and intact matrices whilst the buffer samples showed fragmented particles. The samples exposed to glucose showed some degree of fragmentation but not high as compared to that of nanoparticles exposed to buffer. The release of insulin from this formulation was therefore dependent on a complex interplay between the components of the buffer and the amount of sugar present

Development of a chitosan based glucose responsive nanoparticulate insulin delivery system

Research into responsive polymeric insulin delivery systems for the management of diabetes mellitus is gaining increasing interest due to the rise in the incidence rate and the burden of daily multiple subcutaneous insulin injections that needs to be endured by the patient. The present study attempted to formulate a nanoparticulate glucose responsive insulin delivery system from a natural polymer chitosan, using a safe glucose sensor, phenyl boronic acid (PBA), which is known to interact with glucose. In the present project, a new method for the production of chitosan tripolyphosphate (TPP) nanoparticles via ultrasonication was developed and optimised. The electrostatic method of tagging PBA onto chitosan was unsuccessful, but the method of N-reductive alkylation of introducing the PBA was successful. Evidence of PBA bonding on to chitosan was assessed by FTIR, ToF-SIMS, DSC and glucose adsorption sensitivity measurements. Glucose adsorption sensitivity to PBA-bonded chitosan polymer was directly related to the amount of PBA functionality within the conjugates and the physical nature of the matrices (porous or crystalline) as revealed by scanning electron microscopy (SEM). The nanoparticles showed glucose concentration dependent swelling with swelling decrease at a glucose concentration above 2.5mg/ml. Encapsulation of insulin into the nanoparticulate matrix was achieved by both the ionotropic gelation and polyelectrolyte complexation methods. Smaller particles with z-average between 140 – 150nm, lower Pdi and zeta potential between 17.5-19.1mV were characteristic of particles produced by PEC, whilst slightly larger particles with z-averages between 170-200nm, higher Pdi and zeta potential between +17.6-21.6mV were noticed for the particles produced by ionotropic gelation. Higher encapsulation of insulin of about 90% was achieved using the PEC method as compared to 34% from the ionotropic gelation series. The amount of drug encapsulated in both methods was pH dependent. In vitro xxi glucose dependent insulin release studied on PEC formulations showed a glucose and fructose concentration dependent release which was affected by the buffer system used. Lower insulin release from higher concentration of the sugars was attributed to the formation of bidentate interaction between the diols in the sugar and PBA, which restricts further expansion of the nanoparticles and hence reduces insulin release. This was confirmed by the SEM images of the nanoparticles after exposure to buffer, glucose and fructose in buffers at pH 7.4. Nanoparticles exposed to fructose showed more spherical and intact matrices whilst the buffer samples showed fragmented particles. The samples exposed to glucose showed some degree of fragmentation but not high as compared to that of nanoparticles exposed to buffer. The release of insulin from this formulation was therefore dependent on a complex interplay between the components of the buffer and the amount of sugar present

Microbial Quality of Household Drinking Water in the Sunyani Municipality of Ghana

The health risk associated with the microbial contamination of drinking water has been a major challenge in most households in the developing world. This challenge stems from the fact that water management systems are either inadequate or non-existent. In this study, the microbial quality of household drinking water in the Sunyani Municipality of Ghana was assessed. Thirty water samples were collected from the various households from eight communities for bacteriological analysis using the multiple tube method. The results were recorded as Most Probable Number (MPN) of coliform per 100 ml of water and compared with World Health Organization Guidelines for Drinking water quality. From the study, the mean total coliform of water ranged from 1.75 x 103 to 8.5 x106 cfu/100 ml. Out of the 30 water samples, twenty-two (73.3%) were positive with coliforms. The commonest source of drinking water standpipe had fifty percent of samples contaminated with coliforms. All four samples collected from the borehole were contaminated with coliforms. Out of the 22 coliform-positive samples, 59.1% of them showed positive for faecal coliform, out of which 50% of samples tested positive for the presence of Escherichia coli (E. coli). The study recommends intensive community education on proper water management systems as well as encouraging proper household hygiene practices. Keywords: Total coliforms, E. coli, Most Probable Number, water qualit

Phylogenetic Analysis fails to sort MHC Class II B Exon 2 Alleles by Locus in the Great Frigatebird (Fregata minor)

The major histocompatibility complex (MHC) is a highly polymorphic genetic region, encoding both immune and immune and non-immune receptors found on the surface of cells. The characterization of MHC loci provides a basis for the understanding of population ecology and evolutionary biology. Previous genetic analysis of the Great Frigatebird MHC Class II B exon 2 region revealed a maximum number of 4 alleles revealing the possibility that these alleles can be divided into 2 loci. The goal for this investigation was to determine if we could classify the previously determined alleles of the Great Frigatebird into 2 loci using phylogenetic tree analysis. The methods and results are divided into two sections. In Approach I, we used phylogenetic methods to determine if sequence similarity could create two clusters of alleles, consistent with the haplotype distribution across all 92 birds. This failed due to the incompatibility between haplotype cluster locations and haplotype identities for each individual bird. Approach II used logic-based criteria to group the alleles into 2 loci based upon the patterns of the co-occurrence of individual birds’ haplotypes. Only 26 of the 44 haplotypes were successfully classified into a locus, and further nucleotide sequence analysis prevented definitive placement of the remainder of the 18 haplotypes. The results from both approaches reveal that there could be gene conversion and recombination acting upon the sequences in the loci, to prevent the successful classification of alleles into 2 loci. Future studies on the MHC exon 3 region, known to have more homogenized sequences, could reveal a more definitive allele placement

The Use of Explicit Instruction in Writing Amongst Students of Colleges of Education in the Ashanti Region of Ghana

The study sought to examine the use of Explicit Instruction in writing lessons at some selected Colleges of Education in the Ashanti Region of Ghana. The collective case study design informed by constructivist grounded theory data analysis methods was used. Data were collected and analyzed using three instruments namely a semi-structured interview, sample texts on argumentative and expository essays and observations. The study revealed that combining the cognitive strategy of text structure knowledge application with the metacognitive strategy of self-monitoring supports the development of academic writing in students in the Colleges of Education. Also, students make mistakes in their writing and these mistakes include verb errors, article errors and wrong words. It was also revealed that with regards to Explicit Instruction in the classroom, tutors comprehensively used instructions in the language class to enhance students writing skills. This study further showed that tutors have a variety of evidence-based instructional practices that improve many different skills and student’s writing knowledge. The researcher recommended that students in Colleges of Education in Ghana are made to read extensively outside the curriculum to broaden their vocabulary repertoire so that the over-reliance on tutors for corrections can be minimized

Cross-Linked Dependency of Boronic Acid-Conjugated Chitosan Nanoparticles by Diols for Sustained Insulin Release

Boronic acids have been widely investigated for their potential use as glucose sensors in glucose responsive polymeric insulin delivery systems. Interactions between cyclic diols and boronic acids, anchored to polymeric delivery systems, may result in swelling of the delivery system, releasing the drug. In this study, 4-formylphenylboronic acid conjugated chitosan was formulated into insulin containing nanoparticles via polyelectrolyte complexation. The nanoparticles had an average diameter of 140 ± 12.8 nm, polydispersity index of 0.17 ± 0.1, zeta potential of +19.1 ± 0.69 mV, encapsulation efficiency of 81% ± 1.2%, and an insulin loading capacity of 46% ± 1.8% w/w. Changes in size of the nanoparticles and release of insulin were type of sugar- and concentration-dependent. High concentration of diols resulted in a sustained release of insulin due to crosslink formation with boronic acid moieties within the nanoparticles. The formulation has potential to be developed into a self-regulated insulin delivery system for the treatment of diabetes

Correlating Physicochemical Properties of Boronic Acid-Chitosan Conjugates to Glucose Adsorption Sensitivity

Phenyl boronic acid (PBA), which is known to interact with glucose, was covalently bonded to chitosan by direct reductive N-alkylation of chitosan with 4-formylphenylboronic acid (4-FPBA). Evidence of PBA bonding on chitosan was assessed by FTIR, ToF-SIMS, SEM, DSC and glucose adsorption sensitivity measurements. FTIR spectra showed strong signals at 1560 and 630 cm−1 indicating the formation of p-substituted benzene. Similarly, ToF-SIMS analyses on the conjugates registered fragments of boron ion (B−) at 11.0 m/z whose intensity increased in proportion to 4-FPBA loading. The degree to which PBA was bonded to chitosan was related to the 4-FPBA load used in the reaction (termed F1 through to F6 with increasing 4-FPBA load). Glucose adsorption sensitivity to PBA-bonded chitosan was directly related to the amount of PBA functionality within the conjugates and the physical nature of the matrices (porous or crystalline). Topographic analysis by SEM revealed that PBA-chitosan conjugates F1, F2 and F3 have porous matrices and their sensitivity to glucose adsorption was directly proportional to the degree of PBA substitution onto chitosan. Conversely, conjugates F4, F5 and F6 appeared crystalline under SEM and glucose adsorption sensitivity decreased in proportion to amount of PBA bonded to chitosan. The crystalline nature of the conjugates was confirmed by DSC, where the exothermic event related to the melting of the bonded PBA moiety, occurred at 338 °C. Thus, decreased sensitivity to glucose adsorption by the conjugates can be ascribed to the crystallinity imparted by increased content of the bonded PBA moiety, providing an optimal loading of PBA in terms of maximizing response to glucose

The Impact of the Extraction Method on Allanblackia floribunda Butter’s Physicochemical Properties as a Possible Pharmaceutical Excipient

The extraction method of edible Allanblackia floribunda seed butter is crucial for preserving its constituents. The objective of the present study was to investigate the effects the extraction methods have on the physicochemical properties of A. floribunda butter regarding its potential use as a pharmaceutical excipient. Butter obtained from different extraction methods (including solvent/hexane, cold press, and traditional/hot water) was analyzed for its physicochemical properties such as yield, melting point, relative density, refractive index, moisture content, pH, acid value, saponification value, percentage of free fatty acids, and iodine value as well as beneficial elements and pathogenic microorganisms. All physicochemical parameters were within the standard limits for edible and industrial oils/butter (Codex Stan 210-1999) and were free from pathogenic microorganisms. However, the pH value of all extracts was higher than that of olive oil. The moisture content was higher in the water and hexane extracts compared to the cold-pressed ones. The hexane extract had higher mineral content (calcium, sodium, magnesium, potassium, and iron) than the cold press and hot water extracts. Extraction with hexane gave the highest yield. The identified fatty acids in all extracts are palmitic and stearic (saturated fatty acids), oleic, linoleic, and linolenic (polyunsaturated fatty acids) acids. Based on the physicochemical analysis, A. floribunda seed butter is edible and has the potential as a pharmaceutical excipient in drug delivery