Probing polydopamine adhesion to protein and polymer films: microscopic and spectroscopic evaluation

Polydopamine has been found to be a biocompatible polymer capable of supporting cell growth and attachment, and to have antibacterial and antifouling properties. Together with its ease of manufacture and application, it ought to make an ideal biomaterial and function well as a coating for implants. In this paper, atomic force microscopy was used to measure the adhesive forces between polymer-, protein- or polydopamine-coated surfaces and a silicon nitride or polydopamine-functionalised probes. Surfaces were further characterised by contact angle goniometry, and solutions by circular dichroism. Polydopamine was further characterised with infrared spectroscopy and Raman spectroscopy. It was found that polydopamine functionalisation of the atomic force microscope probe significantly reduced adhesion to all tested surfaces. For example, adhesion to mica fell from 0.27 ± 0.7 nN nm-1 to 0.05 ± 0.01 nN nm-1. The results suggest that polydopamine coatings are suitable to be used for a variety of biomedical applications

Food security and sustainability: Malaysia agenda

Issues pertaining to sustainability and food security in agricultural development are still the main agenda of Malaysia in its vision of being a developed nation. It is basically the government’s responsibility of installing public confidence that food is available and affordable as well as ensuring the sustainability of the agri-food sector, for the welfare of today’s and future generation. Apart from defining food security and sustainability, the paper reviews Malaysia’s position on food security considering the global food security index as well as identification of its strengths and weaknesses. Some of the descriptions are also presented as part of a policy review on food security and sustainability as well as government regulations that have been established to ensure the effective implementation of relevant initiatives. This paper also focuses on agri-food research direction particularly in MARDI in addressing food security and sustainability. It encompasses the areas of research that need to be strengthened to address food security issues and sustainable agriculture through technology and innovation. Discussions within this framework also include the relationship of climate change with food security and sustainability with special emphasis on rice production. This is due to the fact that rice is a major commodity in the context of food security in our country

Synthesization and characterization of chlorhexidine/calcium phosphate/poly(lactic-co-glycolic acid) bone cement

Calcium (Ca) and phosphorus (P) elements are important for bone growth and bone remodeling process while chlorhexidine (CHX) is mainly used as an antiseptic due to its broad antibacterial effects. In this study, CaP nanoparticles were synthesized by a wet chemical route from the precursors of calcium hydroxide (CaOH) and diammonium hydrogen phosphate, (NH4)2HPO4. Poly(lactic-co-glycolic acid) PLGA polymer was incorporated into the mixture of CaP, acted as a matrix binder to form bone cement composite. Different concentrations of CHX (0.5, 1.0, 1.5 and 2.0 mM) were then added into the CaP/PLGA mixtures (CHX/CaP/PLGA bone cements). The bone cements were then characterized by ATR-FTIR, XRD and SEM analyses. The CHX was successfully incorporated into the bone cements, indicated by the appearance of aromatic amine and alkane C–H stretching vibrations which contributed by the ring and long hydrocarbon chain of CHX. The XRD spectra of bone cements showed poorly crystalline phase of apatite. A porous structure of bone cements was also observed with the dispersion of CaP nanoparticles over the PLGA. The CHX/CaP/PLGA bone cement is intended for bone resorption and bone infection applications that require further exploration on its capability to act as bone cement

Formation of carbonated apatite layer in 1.5× simulated body fluid at different refreshing time

Bioactivity analysis in simulated body fluid (SBF) is an experiment or protocol conducted to evaluate the bioactive properties of a sample without involving cells. The bioactive property is claimed based on the formation of apatite layer after immersion in SBF. This analysis consumes expensive chemical reagents and requires complex procedure in preparing and refreshing the solution. Therefore, the aim of this study was to identify significant alteration of refreshing time in the 1.5× SBF to form an apatite layer on a polydopamine (PDA) grafted stainless steel (SS316L) disk. The SS316L disks were pre-treated and grafted with a PDA layer to equip the bioinert metal surface with a bioactive film. The PDA grafted disks were subjected to bioactivity analysis in SBF for 7 days at different refreshing time (24 h, 48 h, 72 h and not refreshed up to 7 d). The surfaces were then characterised by FTIR, SEM-EDX, and contact angle analyses to determine its chemical composition, morphology and wettability properties. The PDA grafted disks that been subjected to 48 h refreshing time in SBF produced homogenous apatite formation with less agglomeration, closest theoretical Ca/P ratio and high hydrophilicity, suggesting the formation of preferable apatite layer with a reduction in the number of refreshing time

Synthesis of tricalcium phosphate at different pH condition

calcium element is crucial for bone health and bone remodeling process. its compound is often used as a material for bone scaffold. one of the common calcium compounds utilized in the development of bone scaffold is tricalcium phosphate (tcp) due to its bioactive and high degradation property. in this study, tcp is synthesized from the precursors of calcium oxide (cao) and diammonium hydrogen phosphate, (nh4)2hpo4. the synthesization was set at three different ph condition – ph 4, ph 7 and ph 10. both precursors were mixed at a stoichiometric ca/p ratio of 1.5, stirred under heat, left to cool, filtered and dried in an oven to solidify. it was then crushed to form powders and subjected to sem-edx and wettability analyses. the morphology images showed that the tcp4 was formed as thin-plate-flakes whereby, the tcp7 and the tcp10 were formed as feathery-thick-blocks materials. as the ph increased, the ca/p ratio and wettability were increased. these results indicated that the synthesization in an alkaline environment favored to the formation of tcp compared to the acidic environment