Low efficiency of conventional fertilizer (quick release fertilizer) application in agricultural sectors has caused environmental pollution and health problems. A method to overcome the drawback of the conventional fertilizer is by controlled release fertilizer (CRF) preparation. CRF is expected to be able to fulfil the nutrient demand of targeted plants. The objective of this research is to prepare CRF by coating NPK fertilizer with multilayer chitosan-polyanion using alginate, pectin, and sodium tripolyphosphate (TPP). In addition, the effect of the layer arrangement modification of material on the rate of nitrogen release was also studied. The mechanical strength of coated fertilizer was analysed by compressive stress test and the properties of the fertilizer coating was observed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The nitrogen release study shows that multilayer of chitosan-alginate (CA)₅, chitosan-pectin (CP)₅, and chitosan-TPP (CT)₅ as coating material was able to increase the compressive stress and decrease the nitrogen release of coated fertilizer. These results are supported by the FTIR analysis which exhibits the formation of ionic interaction between amine group of chitosan and carboxyl group of alginate in chitosan-alginate (CA)₅ layer, carboxyl group of pectin in chitosan-pectin (CP)₅ layer, and phosphate of TPP in chitosan-TPP (CT)₅ layer. On the other hand, the modification of the arrangement of chitosan-alginate layers showed that the fertilizer with the alternating layer arrangement (CA)₅ was able to optimally increase the compressive strength. The mathematical model for the nitrogen release of coated fertilizer is also prepared and simulated with the MATLAB software. The simulation results showed that the nitrogen release of coated fertilizer followed the proposed diffusion mechanism. The obtained diffusivity coefficient value in the layer of chitosan-alginate (CA)₅ is 2.0933 × 10⁻⁶ cm²/s, 2.5606 × 10⁻⁶ cm²/s in chitosan-TPP (CT)₅ layer, and 3.7256 × 10⁻⁶ cm²/s in chitosan-pectin (CP)₅ layer.

Plastics based on low-density polyethylene (LDPE) blends generally have limited miscibility, and it is difficult to obtain a homogeneous blend. Although they show excellent properties, their thermal degradation rate is a concern. This work aims to realize a homogeneous blend with higher chitosan concentration, thus expected to increase its degradation properties. An extrusion technique successfully synthesized LDPE and chitosan blends. The mixtures were prepared by adding maleic anhydride (MA) and tert-butyl peroxybenzoate (TBPB) as a compatibilizer and initiator, respectively. The addition of MA and TBPB resulted in homogeneous blends and using chitosan concentration of 40 %wt resulted in better tensile strength and elongation at break. The water uptake increased along with chitosan concentration in the blends. The thermal behavior analysis of the blends conducted by simultaneous TG/DTA revealed that the increase of chitosan concentration tends to improve the blend's thermal degradation slightly. Moreover, chitosan addition resulted in approximately a hundred times larger biodegradability compared to plastics based on LDPE alone.

The development of fluorescent silica nanoparticles (SNP-RB) from natural amorphous silica and its performance as an Escherichia coli (E. coli) biosensor is described in this paper. SNP-RB was derived from silica recovered from geothermal installation precipitation and modified with the dye, Rhodamine B. The Fourier Infrared (FTIR) confirms the incorporation of Rhodamine B in the silica matrix. Transmission Electron Microscopy (TEM) micrographs show that the SNP-RB had an irregular structure with a particle diameter of about 20–30 nm. The maximum fluorescence spectrum of SNP-RB was recorded at 580 nm, which was further applied to observe the detection performance of the fluorescent nanoparticles towards E. coli. The sensing principle was based on the fluorescence-quenching mechanism of SNP-RB and this provided a wide linear E. coli concentration range of 10–10⁵ CFU/mL with a limit detection of 8 CFU/mL. A rapid response time was observed after only 15 min of incubation of SNP-RB with E. coli. The selectivity of the biosensor was demonstrated and showed that the SNP-RB only gave quenching response only to live E. coli bacteria. The use of SNP-RB as a sensing platform reduced the response time significantly compared to conventional 3-day bacterial assays, as well having excellent analytical performance in terms of sensitivity and selectivity.

A modified functional group of chitosan film was successfully prepared. Maleic anhydride (MA) was used to introduce carboxylic functional groups into chitosan film to enhance the drug loading capacity of the film and also control the drug release. The experiment was carried out by adding various amounts of MA into a chitosan solution, followed by loading the drug into the mixed solution. The drug release study was conducted by immersing the chitosan film in phosphate-buffered saline (PBS) solution (pH 7.4) as a body fluid model. This study was carried out in purpose to study the release kinetics of a drug from the modified chitosan film. Hence, the drug release data obtained were correlated with three mathematical models of drug release kinetics: Higuchi’s model, Peppas’ Model, and First-order model. Finally, the results revealed that the modified chitosan film exhibited a controlled release profile. Among the three mathematical models, the drug release profile from the modified chitosan film was best fitted with the First-order model.

Nanofiber is a widely used biopolymer in medical and industrial applications due to its unique characteristics such as the high surface area to volume ratio and its biocompatibility. This work demonstrates the ability of polyion complex chitosan-alginate to form nanofiber with the addition of polyvinyl alcohol (PVA) by electrospinning. The electrospinning process offers a unique capability to produce natural nanofibers with controlled pore structure using both natural and synthesis polymer or its combination. This research was conducted to optimize the fabrication of chitosan/alginate/PVA nanofibers by varying the conductivity of solution, solvent concentration, and polymer composition. The obtained nanofibers were characterized using Scanning Electron Microscope (SEM) to observe the morphology and Fourier Transform Infrared (FTIR) identify the constituent group. Nanofibers have achieved with the range of mixture solution’s conductivity of 0.5-2.0 Mho/cm. The resulted nanofibers showed a uniform nanofiber with average diameter around 200−400 nm. Although higher acetic acid concentration (as a chitosan solvent) did not change conductivity significantly, it resulted in a larger diameter of nanofibers. Higher sodium alginate concentration in the mixture solution produced nanofibers with higher conductivity and larger diameter.

The objective of this research was to get the mechanism of nano size chitosan particle growth during storage by observing the effect of temperature and initial concentration of chitosan. The products were analyzed using PSA to have the average of particle radius. Nanochitosan solution was prepared by ionic gelation method. This method is described as an electrostatic interaction between positively charged amine with negatively charged polyanion, such as tripolyphosphate (TPP). Chitosan was dissolved in 1% acetic acid and was stirred for 30 minutes. Tween 80 was added to avoid agglomeration. TPP was prepared by dissolving 0.336 g into distilled water. The nano size chitosan was obtained by mixing TPP and chitosan solution dropwise while stirring for 30 minutes. This step was done at 15°C and ambient temperature (about 30°C) and chitosan concentration 0.2%, 0.4% and 0.6%. The results show that temperature during ionic gelation process (15°C and 30°C) does not affect the initial size of the nanoparticles produced as well as the growth of the nanoparticles during storage. On the other hand, initial chitosan concentration strongly affects initial size of the nanoparticles produced and the growth of the nanoparticles during storage. The concentration of chitosan at 0.2%, 0.4%, 0.6% gave initial size of nanoparticle chitosan of 175.3 nm, 337.9 nm, 643.3 nm respectively. On the other hand, the growth mechanism of chitosan nanoparticle depended on its radius(R). At R<500 nm, the growth rate of nanoparticles is controlled by adsorption at the surface of the particles, while at R>500 nm, it is controlled by diffusion in the liquid film around the particles.