Chitosan-Tripoly Phosphate (CS-TPP) Synthesis Through Cross-linking Process: the Effect of Concentration Towards Membrane Mechanical Characteristic and Urea Permeation
Crosslinking reactions are required to modify the functional groups on chitosan and to increase the number of active groups of chitosan. In this study crosslinking reaction of tripolyphospate (TPP) groups on chitosan was conducted in order to produce membrane which functions as candidate of hemodialysis membrane. The mole ratio between chitosan and NaTPP was varied to obtain the best composition of modified materials. Study of TPP concentration effect towards membrane characteristics was conducte durea permeation ability. The resulting membrane was then characterized including tests of thickness, water uptake, tensile strength and membrane hydrophilicity. The results showed that the best composition of membrane occurred in the addition of 0.691 g of NaTPP proved byin creasing water uptake (150%), its highest mechanical strength and releasing the percentage of urea permeation by 44%.
BCR Sequential Leaching for Geochemical Fractions and Assessment of Fe, Ni, and Mn in the Coastal Sediments Sendang Biru Port, East Java, Indonesia
The changes in the aquatic environment by either natural or anthropogenic sources may affect the presence of heavy metals in the sediment of Sendang Biru Port. Heavy metals such as Fe, Ni, and Mn possibly give a negative impact on ecological and biological systems in the sea water. To monitor the status of sediment of the Port Sendang Biru, we investigated the geochemical fraction of Fe, Ni, and Mn in sediment using the BCR (European Community Bureau of Reference) sequential leaching method. The precision test of BCR method showed that Fe, Ni, and Mn has 4.82; 3.73; and 3.16 Relative Standard Deviation (RSD), respectively. The accuracy test of BCR method showed that percentage recovery for Fe, Ni, and Mn were 85.5%; 96.2%; and 63.0%, respectively. The fractionation of Fe, Ni, and Mn in the sediment of Sendang Biru Port showed that Fe was dominant in residual fraction (90.7%), whereas Ni and Mn were dominant in non-residual fraction (78.8% Ni and 77.2% Mn). The dominance of Fe in the residual fraction indicated that Fe was from natural sediment minerals bound to silicate and aluminate, whereas the dominance of Ni and Mn in non-residual fractions was possibly derived from anthropogenic effects. Assessment from index calculation of sediment had the category contaminated at moderate levels by Ni and contaminated at low levels by Fe and Mn.
Rational Design, Synthesis and Evaluation of γ-CD-Containing Cross-Linked Polyvinyl Alcohol Hydrogel as a Prednisone Delivery Platform
This study describes the in-silico rational design, synthesis and evaluation of cross-linked polyvinyl alcohol hydrogels containing γ-cyclodextrin (γ-CDHSAs) as platforms for the sustained release of prednisone (PDN). Through in-silico studies using semi-empirical quantum mechanical calculations, the effectiveness of 20 dicarboxylic acids to generate a specific cross-linked hydrogel capable of supporting different amounts of γ-cyclodextrin (γ-CD) was evaluated. According to the interaction energies calculated with the in-silico studies, the hydrogel made from PVA cross-linked with succinic acids (SA) was shown to be the best candidate for containing γ-CD. Later, molecular dynamics simulation studies were performed in order to evaluate the intermolecular interactions between PDN and three cross-linked hydrogel formulations with different proportions of γ-CD (2.44%, 4.76% and 9.1%). These three cross-linked hydrogels were synthesized and characterized. The loading and the subsequent release of PDN from the hydrogels were investigated. The in-silico and experimental results showed that the interaction between PDN and γ-CDHSA was mainly produced with the γ-CDs linked to the hydrogels. Thus, the unique structures and properties of γ-CDHSA demonstrated an interesting multiphasic profile that could be utilized as a promising drug carrier for controlled, sustained and localized release of PDN.