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This work explores the feasibility of fused deposition modelling (FDM) to produce kenaf fiber/thermoplastic polyurethane (TPU) composites. Internal mixer was used for mixing different weight percentage (0, 5 and 10 wt %) of kenaf fiber with TPU before being extruded to produce filament for FDM feed stock. Addition of kenaf fiber was found to give benefits on dimensional stability of the printed samples which is importance for its implementation in FDM. TPU filled with 10wt% of kenaf fibre showed improvements in hardness and Young modulus of 15% and 49%. However, the tensile strength, elongation at break and density of the printed samples decreased with increasing kenaf fiber loading. This could be explained due to increase of voids and porosity within the material and poor wettability between TPU matrix and kenaf fiber which is evidenced by SEM observation.

Microplastic is classified as fragmented polymeric particles up to 500 microns in diameter. In an aqueous system, microplastic does not always present as a single particle, and these microparticles tend to aggregate and subsequently causing severe ecological risks. The exploration of the underlying mechanisms on how microplastics aggregate in seawater and freshwater enables the prediction of their diffusivity, distribution, and bioavailability in the water environment. In this study microplastic model systems of polypropylene (PP) and poly(vinyl chloride) (PVC) were used to investigate the interactions and aggregation size between microplastics in seawater and with the response anionic sodium dioctyl sulfosuccinate (AOT) surfactant dosages via electrophoretic mobility and Dynamic Light Scattering (DLS) measurements, supported by the UV-Vis spectrum analysis. This investigation revealed that mobile ions present in water ecosystems played a vital role in the surface interactions between microplastics and their aggregation behaviour. The surface charge of both PP and PVC microplastics were switched to a positive value at 5 wt.% of AOT and continued in the negative regime with increasing AOT concentration. Upon the addition of surfactant, surface charge neutralization and aggregation of PP and PVC microplastics were detected; however, the restabilization of microplastic was observed with increasing concentration of surfactant.

Fish processing by-products, such as fish bone waste is usually considered as waste and will be disposed without fully utilizing it. Indeed, this by-product can serve as a cheap bio-resource for the production of high-value product, for instance, as an inexpensive source of calcium phosphate material. In this research, Lutjanus johnii and Lutjanus sebae bones were subjected to thermal calcination to yield different calcium phosphate products. XRD, FTIR and HRTEM-SAED results revealed that biphasic HAp/β-TCP mixture was obtained by heat treatment of Lutjanus johnii bone while a single-phase HAp was prepared from Lutjanus sebae bone. In addition, it was shown that both Lutjanus johnii and Lutjanus sebae bones had a merit in producing B-type carbonated composition that is advantageous for biomedical application. EDX result further corroborated the existence of inorganic elements such as Mg, Na and Sr. With their unique composition, the calcined products deriving from Lutjanus johnii and Lutjanus sebae bones can be further employed to form bioceramic scaffolds for bone engineering applications.

Alginate microspheres are used for controlled drug delivery system; however, the formation and size control of alginate microspheres is necessary for these systems to be effective. Therefore, the influence of stirring speed on the characteristic of alginate microspheres (AMs) via emulsification/gelation method was evaluated. Alginate solution was emulsified into liquid paraffin oil to form water in oil emulsion and followed by cross-linked with Ca2+ ions. The shape and surface characteristics of AMs were determined by scanning electron microscope (SEM). Morphological observation shows that at lower stirring speed, the alginate particles were irregularly shaped with a rough surface. Whereas, increasing stirring speed resulted in spherical microspheres with smoother surface. Particle size analysis by laser diffraction method showed a decreased in mean particle size and more homogeneous distribution as the stirring speed increased. The mean particle size of AMs was found to be in the range of 28.5-69.6 μm. Fourier transform infrared (FTIR) analysis shows that there was no shifting in peak positions in the transmittance spectrum of AMs. This study suggested that the formation of AMs can be synthesis via emulsification/gelation method and the size of the AMs can be tailor by varying the stirring speed.

This review provides an intensive overview of flame retardant coating systems. The occurrence of flame due to thermal degradation of the polymer substrate as a result of overheating is one of the major concerns. Hence, coating is the best solution to this problem as it prevents the substrate from igniting the flame. In this review, the descriptions of several classifications of coating and their relation to thermal degradation and flammability were discussed. The details of flame retardants and flame retardant coatings in terms of principles, types, mechanisms, and properties were explained as well. This overview imparted the importance of intumescent flame retardant coatings in preventing the spread of flame via the formation of a multicellular charred layer. Thus, the intended intumescence can reduce the risk of flame from inherently flammable materials used to maintain a high standard of living.

Alginate microspheres (AMs) have received much attention as a novel drug delivery system owing to various advantages of alginate such as inexpensiveness, nontoxicity, biocompatibility and biodegradability. The well-designed fabrication method is essential to achieve desired AMs suitable for specific drug delivery system. Reports on AMs preparation techniques have increased rapidly in the last decade. A number of synthesis parameters have been investigated for the improvement of physical, chemical and biological properties of AMs. Hence, this review summarizes the work to date on the fabrication techniques of AMs for drug delivery system, including spray-drying, extrusion and emulsification/gelation technique. Besides, the influence of various factors such as alginate concentration, oil phase, surfactant, cross-linker concentrations, cross-linking time, stirring speed, model drug and drug content on the morphologies, properties and encapsulation efficiency (EE) of AMs via extrusion and emulsification/gelation technique are summarized. Before embarking on the development of any drug delivery system, a thorough understanding of drug release mechanism and factors that impact the drug release profile are essential, which are also covered in this review.

Polymeric materials are currently being investigated as potential drug carriers. However, their performance is highly influenced by various factors especially the formulation variables. Herein, doxycycline-loaded PLA microspheres were prepared using the double emulsion solvent evaporation method and the effects of formulation variables were investigated. Specifically, particle size distribution, encapsulation efficiency and in vitro drug release behavior were evaluated for different formulations. In addition, antimicrobial activity of the doxycycline-loaded PLA microspheres was studied through the agar well diffusion method. Results showed that the addition of 4% NaCl into the external aqueous phase helped to improve the encapsulation efficiency, which subsequently influenced the drug release behavior of the microspheres. Specifically, about 66% of the doxycycline was encapsulated within PLA microspheres. Notably, slower drug release behavior was obtained by increasing the aqueous/organic phase volume ratio, polymer concentration and NaCl concentration in the external aqueous phase. However, increase in the particle size of microspheres resulted in lower encapsulation and antibacterial efficiencies. This study reveals that through proper manipulation of formulation variables, high-performance PLA microspheres suitable for use as carrier for various drugs can be prepared.

In this work, thermal and rheological properties of self-fabricated polylactic acid (PLA) filaments without and with 10-wt% polyethylene glycol (PLA/0PEG and PLA/10PEG, respectively) were investigated, and the properties were compared with a commercial PLA filament used for fused deposition modeling (FDM). The result showed that the melt flow index for self-fabricated filaments was comparable with commercial filaments at approximately 10 g/10 min at 190°C, suggesting suitability to be used as filament for FDM with well-wetted layers. Variation in thermal properties was found in PLA/10PEG with 20°C higher cold crystallization temperature ( T cc) after FDM in which disruption of the molecular arrangement reduced the ability for chain alignment and folding. The result also revealed that addition of PEG decreased the storage modulus ( G′), loss modulus ( G″), and complex viscosity ( η*), resulting in slow crystallization behavior, and however, the properties did not induce degradation of the filaments and printing products.

Formulated, processed, and dried Aloe polysaccharides thin film sandwiched between ITO as bottom electrode and Au as top electrode has been adopted as an artificial synapse to emulate behavior of neuromorphic computing. The synaptic plasticity or weight has been modulated with this simple metal-insulator-metal structure by applying voltage sweep and voltage pulse, with excitatory postsynaptic current being monitored. Synaptic potentiation and depression has been demonstrated by applying 6 consecutive sweeps of voltage in positive and negative polarity, respectively. By varying number (10 – 50) of voltage pulses, variable synaptic weight has been measured with paired pulse facilitation and post-tetanic potentiation indexes of 2.61x10-6and 1.45x10-4, respectively. The short-term plasticity and long-term potentiation can be clearly revealed when applying 40 pulses and beyond, with extracted time constants of approximately 28 s at 40 pulses and 90 s at 50 pulses.

The critical feature in trachea replacement is to provide a hollow cylindrical framework that is laterally stable and longitudinally flexible, facilitating cartilage and epithelial tissue formation. Despite advanced techniques and sources of materials used, most inherent challenges are related to the complexity of its anatomy. Limited blood supply leads to insufficient regenerative capacity for cartilage and epithelium. Natural and synthetic scaffolds, different types of cells, and growth factors are part of tissue engineering approaches with varying outcomes. Pre-vascularization remains one of the crucial factors to expedite the regenerative process in tracheal reconstruction. This review discusses the challenges and strategies used in tracheal tissue engineering, focusing on scaffold implantation in clinical and preclinical studies conducted in recent decades.

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) are two common dental regenerative treatments targeted at reconstructing damaged periodontal tissue and bone caused by periodontitis. During GTR/GBR treatment, a barrier membrane is placed in the interface between the soft tissue and the periodontal defect to inhibit soft tissue ingrowth and creating a space for the infiltration of slow-growing bone cells into the defect site. Recently, asymmetric resorbable-based barrier membrane has received a considerable attention as a new generation of GTR/GBR membrane. Despite numerous literatures about asymmetric-based membrane that had been published, there is lacks comprehensive review on asymmetric barrier membrane that particularly highlight the importance of membrane structure for periodontal regeneration. In this review, we systematically cover the latest development and advancement of various kinds of asymmetric barrier membranes used in periodontal GTR/GBR application. Herein, the ideal requirements for constructing a barrier membrane as well as the rationale behind the asymmetric design, are firstly presented. Various innovative methods used in fabricating asymmetric barrier membrane are being further discussed. Subsequently, the application and evaluation of various types of asymmetric barrier membrane used for GTR/GBR are compiled and extensively reviewed based on the recent literatures reported. Based on the existing gap in this field, the future research directions of asymmetric resorbable-based barrier membrane such as its combination potential with bone grafts, are also presented.

The astonishing outbreak of SARS-CoV-2 coronavirus, known as COVID-19, has attracted numerous research interests, particularly regarding fabricating antimicrobial surface coatings. This initiative is aimed at overcoming and minimizing viral and bacterial transmission to the human. When contaminated droplets from an infected individual land onto common surfaces, SARS-CoV-2 coronavirus is able to survive on various surfaces for up to 9 days. Thus, the possibility of virus transmission increases after touching or being in contact with contaminated surfaces. Herein, we aim to provide overviews of various types of antiviral and antimicrobial coating agents, such as antimicrobial polymer-based coating, metal-based coating, functional nanomaterial, and nanocomposite-based coating. The action mode for each type of antimicrobial agent against pathogens is elaborated. In addition, surface properties of the designed antiviral and antimicrobial polymer coating with their influencing factors are discussed in this review. This paper also exhibits several techniques on surface modification to improve surface properties. Various developed research on the development of antiviral/antimicrobial polymer coating to curb the COVID-19 pandemic are also presented in this review.

This study illustrated the potential applications of thermoresponsive poly(N-isopropylacrylamide) (PNIPAm) grafted nylon membranes with different grafting yields and grafting architecture. The thermoresponsive gating performance at temperatures below and above the lower critical solution temperature (LCST) of PNIPAm (32 °C) were demonstrated. The linear PNIPAm-grafted nylon membrane exhibited a sharp response over the temperature range 20–40 °C. The grafting yield of 25.5% and 21.9%, for linear and crosslinked PNIPAm respectively, exhibited highest thermoresponsive gating function for water flux and had a stable and repeatable “open-closed” switching function over 5 cycle operations. An excellent oil/water separation was obtained at T < 32 °C, at which the hydrophilic behavior was observed. The linear PNIPAm-grafted nylon membrane with 35% grafting yield had the highest separation efficiency of 99.7%, while PNIPAm structures were found to be independent of the separation efficiency. In addition, the membranes with thermoresponsive gas permeability were successfully achieved. The O2 and CO2 transmission rates through the PNIPAm-grafted nylon membranes decreased when the grafting yield increased, showing the better gas barrier property. The permeability ratio of CO2 to O2 transmission rates of both PNIPAm architectures at 25 °C and 35 °C were around 0.85 for low grafting yields, and approximately 1 for high grafting yields. Ultimately, this study demonstrated the possibility of using these thermoresponsive smart membranes in various applications.

Stem cell-based therapy appears as a promising strategy to induce regeneration of damaged and diseased tissues. However, low survival, poor engraftment and a lack of site-specificity are major drawbacks. Polysaccharide hydrogels can address these issues and offer several advantages as cell delivery vehicles. They have become very popular due to their unique properties such as high-water content, biocompatibility, biodegradability and flexibility. Polysaccharide polymers can be physically or chemically crosslinked to construct biomimetic hydrogels. Their resemblance to living tissues mimics the native three-dimensional extracellular matrix and supports stem cell survival, proliferation and differentiation. Given the intricate nature of communication between hydrogels and stem cells, understanding their interaction is crucial. Cells are incorporated with polysaccharide hydrogels using various microencapsulation techniques, allowing generation of more relevant models and further enhancement of stem cell therapies. This paper provides a comprehensive review of human stem cells and polysaccharide hydrogels most used in regenerative medicine. The recent and advanced stem cell microencapsulation techniques, which include extrusion, emulsion, lithography, microfluidics, superhydrophobic surfaces and bioprinting, are described. This review also discusses current progress in clinical translation of stem-cell encapsulated polysaccharide hydrogels for cell delivery and disease modeling (drug testing and discovery) with focuses on musculoskeletal, nervous, cardiac and cancerous tissues.

Carbon can form different allotropes due to its tetravalency. Different forms of carbon such as carbon nanotubes (CNTs), carbon nanofibers, graphene, fullerenes, and carbon black can be used as nanofillers in order to enhance the properties of polymer nanocomposites. These carbon nanomaterials are of interest in nanocomposites research and other applications due to their excellent properties, such as high Young’s Modulus, tensile strength, electrical conductivity, and specific surface area. However, there are some flaws that can be found in the carbon nanoparticles such as tendency to agglomerate, insoluble in aqueous or organic solvents or being unreactive with the polymer surface. In this study, the aim is to study functionalization in order to rectify some of these shortcomings by attaching different functional groups or particles to the surface of these carbon nanoparticles; this also enables the synthesis of high-performance polymer nanocomposites. The main findings include the effects of functionalization on carbon nanoparticles and the applications of polymer nanocomposites with carbon nanoparticles as nanofillers in the industry. Additionally, the different methods used to produce polymer composites such as in situ polymerization, solution mixing and melt blending are studied, as these methods involve the dispersion of carbon nanofillers within the polymer matrix.

Surgical reconstruction of extensive tracheal lesions is challenging. It requires a mechanically stable, biocompatible, and nontoxic material that gradually degrades. One of the possible solutions for overcoming the limitations of tracheal transplantation is a three-dimensional (3D) printed tracheal scaffold made of polymers. Polymer blending is one of the methods used to produce material for a trachea scaffold with tailored characteristics. The purpose of this study is to evaluate the mechanical and in vitro properties of a thermoplastic polyurethane (TPU) and polylactic acid (PLA) blend as a potential material for 3D printed tracheal scaffolds. Both materials were melt-blended using a single screw extruder. The morphologies (as well as the mechanical and thermal characteristics) were determined via scanning electron microscopy (SEM), Fourier Transform Infrared (FTIR) spectroscopy, tensile test, and Differential Scanning calorimetry (DSC). The samples were also evaluated for their water absorption, in vitro biodegradability, and biocompatibility. It is demonstrated that, despite being not miscible, TPU and PLA are biocompatible, and their promising properties are suitable for future applications in tracheal tissue engineering.

Poly(l-lactide-co-e-caprolactone) (PLCL) is a potential material to fabricate scaffolds for vascular tissue engineering. In this work, scaffolds with a multilayered structure comprising a combination of porous and fibrous structures were developed. PLCL was used to fabricate the inner layer of the tubular scaffolds using the freeze-drying technique. The inner layer was then covered by an outer layer fabricated by the melt-spinning technique. The morphology and physical structure of the scaffolds were evaluated through SEM micrographs. The freeze-drying technique formed a porous structure, while the melt-spinning method formed a fibrous structure for the bilayer scaffolds. Physicochemical properties were also investigated by DSC and FTIR measurements; no new functional groups were found to have formed during the freeze-drying or melt-spinning processes. Mechanical properties and fracture mechanism under a tensile loading condition were carefully analyzed to characterize the deformation and fracture behaviors. It was found that the bilayer scaffolds exhibited better mechanical properties than single-layer scaffolds with higher maximum stress at 675.41 kPa, strain at maximum stress at 69.42%, fracture energy at 412.45 kJ/m3 and burst pressure at 147.93 kPa. Porosity, swelling ratio and in vitro biodegradation were measured to ensure its suitability for vascular tissue applications. The bilayer scaffolds with both porous and fibrous structures meet the requirements for vascular tissue engineering.

This research focuses on the development of eco-friendly denture adhesives (EFDAs) by studying the effects of the addition of different types of native and modified natural starches as fill...

The switching behaviors of polysaccharides-based resistive random access memories change substantially depending on the electrical inputs. Here, the switching dynamics of the device are presented by varying the applied current compliance ( ${I}_{\text {CC}}$ ) and voltage sweeping rate ( $\nu $ ). The results show that the device resistance in the low-resistance state ( ${R}_{\text {LRS}}$ ) can be modulated over five orders of magnitude by varying ${I}_{\text {CC}}$ and $\nu $ in the typical current–voltage measurements. The ${R}_{\text {LRS}}$ modulation is attributed to the variable tunneling gap between the filament tip and the top electrode (TE). Conductance quantization is observed once a single-atomic contact with resistance $\le 12.9~\text{k}\Omega $ is formed. Depending on the TEs, both integer and half-integer multiples of quantization levels are being observed, demonstrating its potential for multilevel data storage. In addition, the results unveil the stochastic strengthening and rupturing of the filament as modulated by periodic voltage pulses, thus enabling the device to operate in both volatile and nonvolatile modes. The device offers excellent switching dynamics for preliminary emulation of synapselike learning and forgetting behaviors in neural junctions for next-generation neuromorphic computing systems.

An earlier study showed that the behaviour of chitosan-poly(methacrylic acid‑co‑N‑isopropylacrylamide) [chitosan‑p(MAA‑co‑NIPAM)] hydrogels synthesized at different reaction times are affected with regard to their pH and temperature sensitivities. The study was continued in this paper to identify the effects of different reaction times on the degradation, efficiency of rifampicin (Rif) loading and the Rif release profile under two different pH conditions (acidic and basic). The results that were obtained showed that the hydrogel had a faster degradation rate in the acidic condition than in the basic condition, where there was a loss of approximately 50% and 20%, respectively in its original weight within two weeks. The Rif loading efficiency was within 50% and the drug release was controlled by characteristics that were developed beyond the polymerization stages of the synthesis. Therefore, the reaction time for the synthesis of the hydrogel can be considered as a way to control the behaviour of the hydrogel as well as to modify the drug release profile in the chitosan‑p(MAA‑co‑NIPAM) hydrogel.

In this study, water at high temperatures (150, 175, 200 °C) and in a vacuum state (−0.1 MPa) was applied to graphite nanosheets to enhance surface activity to promote the formation of oxygen-containing functional groups through supercritical water treatment. Nylon 610 nanocomposites (with treated or untreated nanosheets as nanofillers) were then synthesized using interfacial polymerization. X-ray diffraction (XRD) analysis showed that the water treatment did not alter the crystal structure of the carbon nanosheets. Additionally, Fourier transform infrared spectroscopy (FTIR) analysis showed the presence of amide peaks within the nanocomposites, indicating the presence of hydrogen bonding between the nanosheets and the polymer matrix. The intensity of the amide peaks was higher for nanocomposites combined with treated nanosheets than untreated ones. This hydrogen bonding is beneficial to the conductivity of the nanocomposites. The conductivity of treated nanosheets/nylon nanocomposites generally decreased with increasing wt%, while the conductivity of untreated nanosheets/nylon nanocomposites increased with increasing wt%. The decrementing of conductivity in the treated nanosheets/nylon nanocomposites is due to the agglomeration of the nanosheets within the composite. This is in in line with scanning electron microscopy (SEM) results which showed that at higher wt%, the aggregation condition tended to occur. The highest conductivity obtained is 0.004135 S/m, as compared to the conductivity of neat nylon 610, which is 10−14 S/m. This improvement in electrical properties can be attributed to the intact structure of the nanosheets and the interaction between the nanofillers and the nylon 610 matrix. The optimum nylon 610 nanocomposite synthesized was the one incorporated with 0.5 wt% graphite nanosheets treated at 200 °C and −0.1 MPa, which possess the highest conductivity.

Oxidative stress and inflammation are two common risk factors of various life-threatening disease pathogenesis. In recent years, medicinal plants that possess antioxidant and anti-inflammatory activities were extensively studied for their potential role in treating and preventing diseases. Spilanthes acmella (S. acmella), which has been traditionally used to treat toothache in Malaysia, contains various active metabolites responsible for its anti-inflammatory, antiseptic, and anesthetic bioactivities. These bioactivities were attributed to bioactive compounds, such as phenolic, flavonoids, and alkamides. The review focused on the summarization of in vitro and in vivo experimental reports on the antioxidant and anti-inflammatory actions of S. acmella, as well as how they contributed to potential health benefits in lowering the risk of diseases that were related to oxidative stress. The molecular mechanism of S. acmella in reducing oxidative stress and inflammatory targets, such as inducible nitric oxide synthase (iNOS), transcription factors of the nuclear factor-κB family (NF-κB), cyclooxygenase-2 (COX-2), and mitogen-activated protein kinase (MAPK) signaling pathways were discussed. Besides, the antioxidant potential of S. acmella was measured by total phenolic content (TPC), total flavonid content (TFC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and superoxide anion radical scavenging (SOD) and thiobarbituric acid reactive substance (TBARS) assays. This review revealed that S. acmella might have a potential role as a reservoir of bioactive agents contributing to the observed antioxidant, anti-inflammatory, and health beneficial effects.

Increased life expectancy has led to an increase in the use of bone substitutes in numerous nations, with over two million bone-grafting surgeries performed worldwide each year. A bone defect can be caused by trauma, infections, and tissue resections which can self-heal due to the osteoconductive nature of the native extracellular matrix components. However, natural self-healing is time-consuming, and new bone regeneration is slow, especially for large bone defects. It also remains a clinical challenge for surgeons to have a suitable bone substitute. To date, there are numerous potential treatments for bone grafting, including gold-standard autografts, allograft implantation, xenografts, or bone graft substitutes. Tricalcium phosphate (TCP) and hydroxyapatite (HA) are the most extensively used and studied bone substitutes due to their similar chemical composition to bone. The scaffolds should be tested in vivo and in vitro using suitable animal models to ensure that the biomaterials work effectively as implants. Hence, this article aims to familiarize readers with the most frequently used animal models for biomaterials testing and highlight the available literature for in vivo studies using small and large animal models. This review summarizes the bioceramic materials, particularly HA and β-TCP scaffolds, for bone defects in small and large animal models. Besides, the design considerations for the pre-clinical animal model selection for bone defect implants are emphasized and presented.

Oxidative stress and inflammation are two common risk factors of various life-threatening disease pathogenesis. In recent years, medicinal plants that possess antioxidant and anti-inflammatory activities were extensively studied for their potential role in treating and preventing diseases. Spilanthes acmella (S. acmella), which has been traditionally used to treat toothache in Malaysia, contains various active metabolites responsible for its anti-inflammatory, antiseptic, and anesthetic bioactivities. These bioactivities were attributed to bioactive compounds, such as phenolic, flavonoids, and alkamides. The review focused on the summarization of in vitro and in vivo experimental reports on the antioxidant and anti-inflammatory actions of S. acmella, as well as how they contributed to potential health benefits in lowering the risk of diseases that were related to oxidative stress. The molecular mechanism of S. acmella in reducing oxidative stress and inflammatory targets, such as inducible nitric oxide synthase (iNOS), transcription factors of the nuclear factor-κB family (NF-κB), cyclooxygenase-2 (COX-2), and mitogen-activated protein kinase (MAPK) signaling pathways were discussed. Besides, the antioxidant potential of S. acmella was measured by total phenolic content (TPC), total flavonid content (TFC), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and superoxide anion radical scavenging (SOD) and thiobarbituric acid reactive substance (TBARS) assays. This review revealed that S. acmella might have a potential role as a reservoir of bioactive agents contributing to the observed antioxidant, anti-inflammatory, and health beneficial effects.

A combination of bioactive scaffold with drug delivery of therapeutic agents is a great deal to locally treat bone infections. However, controllable drug release behaviours for different types of drug-incorporated scaffold have been not comprehensively compared. In this study, novel technique was proposed with the addition of bioactive agents in microspheres was incorporated into carbonate apatite (CO3Ap) scaffold. A simple slurry-dipping method by dispersion of 0.8 wt% suspension of gentamicin (GEN)-loaded polylactic acid (PLA) microsphere (GENMS) using an ultrasonic bath was used to coat the scaffold. GENMS was fabricated by double emulsion. This coated scaffold was compared to the GEN coated scaffold without microsphere and uncoated scaffold with direct loading of GEN. It was confirmed that the microsphere coating did not inhibit the apatite growth of the scaffold when immersed in Hank’s Balance Salt Solution for 4 weeks. The drug release profile exhibited the initial burst and sustained drug release could be improved by the presence of GENMS in the coated scaffold. Moreover, the kinetic release study supported the findings of different drug release based on zero-order, first-order, Higuchi and Korsmeyer–Peppas models. The results showed that drug release mechanisms were diffusion and degradation controlled for scaffold, while for coated scaffolds led to diffusion and degradation of chitosan and microsphere. Rougher surface of the scaffold by the adhered GENMS on the scaffold facilitated cell proliferation. In short, this multifunctional coated bioactive scaffold has the potential to enhance cell attachment and provide local of controlled drug delivery for bone tissue engineering improvement.

Currently, numerous attentions have been given by researchers and industry to explore and develop biodegradable polymer composites. Organic fillers like natural polymers are added into biodegradable composites to improve the properties of composites, reduce the production cost, and enhance the processing condition. This review is carried out to evaluate the effect of protein-based fillers on biodegradable polymer composites in light of miscibility and compatibilization. The factors affecting compatibility such as composition of fillers, coupling agent, and methods to achieve compatibilization are also discussed.

Coal bottom ash (CBA) is a one of coal combustion by-products from the production of electricity in coal fired power plants. Although it is classified as hazardous waste and the usage of this material is very limited, it is also an alternative material that benefits the construction industry in replacing cement or fine aggregate at certain percentage. CBA contains heavy metals. The possibility of heavy metals fluxes from the concrete is of great concern as it may cause highly potential adverse environmental impacts especially if the concentration is at beyond regulated standards. This will stop the reuse of CBA in the construction industry and may lead to deficit to entities like power plants due to the high cost of CBA disposal. Thus, this paper presents an overview on the studies of heavy metals immobilization for building materials in the construction industry. Techniques applied for heavy metals immobilization during solidification and stabilization (S/S) process using alkali activation, hydration, thermal treatment and synthesis of dicalcium silicate (β-Ca2SiO4) were briefly described.

Poly(lactic) acid (PLA) is well known as a drug carrier in drug delivery system. Double emulsion and solvent evaporation technique was used to encapsulate gentamicin within PLA microspheres. The ability of PLA microspheres to encapsulate gentamicin was investigated at three different wt%; 0.125%, 0.25% and 0.375%. The highest encapsulation efficiency (42.3%) and drug loading (26.5x10-3%) was observed at 0.375 wt% gentamicin loaded. For antimicrobial assay, the diameter for zone of inhibition was measured and compared for each wt% of gentamicin used. This evaluation was done to determine the effectiveness of gentamicin delivery from the PLA microspheres to inhibit the growth of Staphylococcus aureus. The higher wt% of gentamicin loaded into the PLA microspheres, the larger the diameter for zone of inhibition was obtained with the highest diameter at 0.375 wt% (2.3 cm). The study showed that the PLA is having potential to serve as a slow and sustained release drug delivery vehicle since the inhibition zone only can be measured after day 3 of incubation.

Alkali-silica reaction causes major problems in concrete structures due to the rapidity of its deformation. Factors that affect ASR include the alkali and silica content, relative humidity, temperature and porosity of the concrete, making the relationship a complex phenomenon to be understood. In investigating the mechanical deformation of the structure, the theory of continuum damage mechanics proves to be a suitable method. Damage mechanics can be used to predict the physical and chemical behavior of a structure, making it an appropriate method to study the behavior of the structure under the influence of alkali-silica reactivity. Therefore solution of the damage model is critically needed to overcome the concrete deformation problem. In this research, an engineering example of a thermo-chemo-hygro-mechanical model of a concrete gravity dam at the macroscale and coupled with the mesoscale will be studied for varying environmental conditions of temperature and relative humidity. The simulation was developed using the stochastic finite element software. Investigations found that temperature, as well as relative humidity influences the latency and characteristic time constants, which dictate the rapidity of ASR expansion into the structure, rendering heterogeneous values across the cross-section of the structure according to the relative humidity and temperature distribution.

In this study, chitosan-poly(methacrylic acid-co-N-isopropylacrylamide) [chitosan-p(MAA-co-NIPAM)] hydrogels were synthesized by emulsion polymerization. In order to be used as a carrier for drug delivery systems, the hydrogels had to be biocompatible, biodegradable and multi-responsive. The polymerization was performed by copolymerize MAA and NIPAM with chitosan polymer to produce a chitosan-based hydrogel. Due to instability during synthesis and complexity of components to produce the hydrogel, further study at different times of reaction is important to observe the synthesis process, the effect of end product on swelling behaviour and the most important is to find the best way to control the hydrogel synthesis in order to have an optimal swelling behaviour for drug release application. Studied by using Fourier transform infra-red (FTIR) spectroscopy found that, the synthesized was successfully produced stable chitosan-based hydrogel with PNIPAM continuously covered the outer surface of hydrogel which influenced much on the stability during synthesis. The chitosan and PMAA increased the zeta potential of the hydrogel and the chitosan capable to control shrinkage above human body temperature. The chitosan-p(MAA-co-NIPAM) hydrogels also responses to pH and temperature thus improved the ability to performance as a drug carrier.