Wound healing is a critical but complex biological process of skin tissue repair and regeneration resulting from various systems working together at the cellular and molecular levels. Quick wound healing and the problems associated with traditional wound repair techniques are being overcome with multifunctional materials. Over time, this research area has drawn significant attention. Metal-organic frameworks (MOFs), owning to their peculiar physicochemical characteristics, are now considered a promising class of well-suited porous materials for wound healing in addition to their other biological applications. This detailed literature review provides an overview of the latest developments in MOFs for wound healing applications. We have discussed the synthesis, essential biomedical properties, wound-healing mechanism, MOF-based dressing materials, and their wound-healing applications. The possible major challenges and limitations of MOFs have been discussed, along with conclusions and future perspectives. This overview of the literature review addresses MOFs-based wound healing from several angles and covers the most current developments in the subject. The readers may discover how the MOFs advanced this discipline by producing more inventive, useful, and successful dressings. It influences the development of future generations of biomaterials for the healing and regeneration of skin wounds.
Climate change caused by the greenhouse gases CO2 remains a topic of global concern. To mitigate the excessive levels of anthrophonic CO2 in the atmosphere, CO2 capture methods have been developed and among these, adsorption is an especially promising method. This paper presents a series of amine functionalized biochar obtained from desiccated coconut waste (amine-biochar@DCW) for use as CO2 adsorbent. They are ethylenediamine-functionalized biochar@DCW (EDA-biochar@DCW), diethylenetriamine-functionalized biochar@DCW (DETA-biochar@DCW), triethylenetetramine-functionalized biochar@DCW (TETA-biochar@DCW), tetraethylenepentamine-functionalized biochar@DCW (TEPA-biochar@DCW), and pentaethylenehexamine-functionalized biochar@DCW (PEHA-biochar@DCW). The adsorbents were obtained through amine functionalization of biochar and they are characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, Brunauer-Emmett-Teller (BET), and thermogravimetric analysis (TGA). The CO2 adsorption study was conducted isothermally and using a thermogravimetric analyzer. From the results of the characterization analyses, a series of amine-biochar@DCW adsorbents had larger specific surface area in the range of 16.2 m2/g-37.1 m2/g as compare to surface area of pristine DCW (1.34 m2/g). Furthermore, the results showed an increase in C and N contents as well as the appearance of NH stretching, NH bending, CN stretching, and CN bending, suggesting the presence of amine on the surface of biochar@DCW. The CO2 adsorption experiment shows that among the amine modified biochar adsorbents, TETA-biochar@DCW has the highest CO2 adsorption capacity (61.78 mg/g) when using a mass ratio (m:m) of biochar@DCW:TETA (1:2). The adsorption kinetics on the TETA-biochar@DCW was best fitted by the pseudo-second model (R2 = 0.9998), suggesting the adsorption process occurs through chemisorption. Additionally, TETA-biochar@DCW was found to have high selectivity toward CO2 gas and good reusability even after five CO2 adsorption-desorption cycles. The results demonstrate the potential of novel CO2 adsorbents based on amine functionalized on desiccated coconut waste biochar.
Porous structured silicon or porous silicon (PS) powder was prepared by chemical etching of silicon powder in an etchant solution of HF: HNO₃: H₂O (1:3:5 v/v). An immersion time of 4 min was sufficient for depositing Cu metal from an aqueous solution of CuSO₄ in the presence of HF. Scanning electron microscopy (SEM) analysis revealed that the Cu particles aggregated upon an increase in metal content from 3.3 wt% to 9.8 wt%. H₂-temperature programmed reduction (H₂-TPR) profiles reveal that re-oxidation of the Cu particles occurs after deposition. Furthermore, the profiles denote the existence of various sizes of Cu metal on the PS. The Cu-PS powders show excellent catalytic reduction on the p-nitrophenol regardless of the Cu loadings.
Porous silicon (PSi) layers were formed on a p-type Si wafer. Six samples were anodised electrically with a 30 mA/cm² fixed current density for different etching times. The samples were coated with a 50-60 nm gold layer and annealed at different temperatures under Ar flow. The morphology of the layers, before and after annealing, formed by this method was investigated by scanning electron microscopy (SEM). Photoacoustic spectroscopy (PAS) measurements were carried out to measure the thermal diffusivity (TD) of the PSi and Au/PSi samples. For the Au/PSi samples, the thermal diffusivity was measured before and after annealing to study the effect of annealing. Also to study the aging effect, a comparison was made between freshly annealed samples and samples 30 days after annealing.
Despite its attractive features for energy saving separation, the performance of forward osmosis (FO) has been restricted by internal concentration polarization and fast fouling propensity that occur in the membrane sublayer. These problems have significantly affected the membrane performance when treating highly contaminated oily wastewater. In this study, a novel double-skinned FO membrane with excellent anti-fouling properties has been developed for emulsified oil-water treatment. The double-skinned FO membrane comprises a fully porous sublayer sandwiched between a highly dense polyamide (PA) layer for salt rejection and a fairly loose dense bottom zwitterionic layer for emulsified oil particle removal. The top dense PA layer was synthesized via interfacial polymerization meanwhile the bottom layer was made up of a zwitterionic polyelectrolyte brush - (poly(3-(N-2-methacryloxyethyl-N,N-dimethyl) ammonatopropanesultone), abbreviated as PMAPS layer. The resultant double-skinned membrane exhibited a high water flux of 13.7 ± 0.3 L/m2.h and reverse salt transport of 1.6 ± 0.2 g/m2.h under FO mode using 2 M NaCl as the draw solution and emulsified oily solution as the feed. The double-skinned membrane outperforms the single-skinned membrane with much lower fouling propensity for emulsified oil-water separation.
Halloysite (HNT) is treated with sulfuric acid and the physico-chemical properties of its morphology, surface activity, physical and chemical properties have been investigated when HNT is exposed to sulfuric acid with treatment periods of 1 h (H1), 3 h (H3), 8 h (H8), and 21 h (H21). The significance of this and similar work lies in the importance of using HNT as a functional material in nanocomposites. The chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR). The spectrum demonstrates that the hydroxyl groups were active for grafting modification using sulfuric acid, promoting a promising potential use for halloysite in ceramic applications as filler for novel clay-polymer nanocomposites. From the X-ray diffraction (XRD) spectrum, it can be seen that the sulfuric acid breaks down the HNT crystal structure and alters it into amorphous silica. In addition, the FESEM images reveal that the sulfuric acid treatment dissolves the AlO₆ octahedral layers and induces the disintegration of SiO₄ tetrahedral layers, resulting in porous nanorods. The Bruncher-Emmett-Teller (BET) surface area and total pore volume of HNTs showed an increase. The reaction of the acid with both the outer and inner surfaces of the nanotubes causes the AlO₆ octahedral layers to dissolve, which leads to the breakdown and collapse of the tetrahedral layers of SiO₄. The multi-fold results presented in this paper serve as a guide for further HNT functional treatment for producing new and advanced nanocomposites.
Chitosan-based hemostats are promising candidates for immediate hemorrhage control. However, they have some disadvantages and require further improvement to achieve the desired hemostatic efficiency. Here, a series of 1% Ga2O3-containing mesoporous bioactive glass-chitosan composite scaffolds (Ga-MBG/CHT) were constructed by the lyophilization process and the effect of various concentrations of Ga-MBG (10, 30, and 50 wt %) on the hemostatic function of the CHT scaffold was assessed as compared to that of Celox Rapid gauze (CXR), a current commercially available chitosan-coated hemostatic gauze. The prepared scaffolds exhibited >79% porosity and showed increased water uptake compared to that in CXR. The results of coagulation studies showed that pure CHT and composite scaffolds exhibited increased hemostatic performance with respect to CXR. Furthermore, the composite scaffold with the highest Ga-MBG content (50 wt %) had increased capability to enhancing thrombus generation, blood clotting, and platelet adhesion and aggregation than that of the scaffold made of pure CHT. The antibacterial efficacy and biocompatibility of the prepared scaffolds were also assessed by a time-killing assay and an Alamar Blue assay, respectively. Our results show that the antibacterial effect of 50% Ga-MBG/CHT was more pronounced than that of CHT and CXR. The cell viability results also demonstrated that Ga-MBG/CHT composite scaffolds had good biocompatibility, which facilitates the spreading and proliferation of human dermal fibroblast cells even with 50 wt % Ga-MBG loading. These results suggest that Ga-MBG/CHT scaffolds could be a promising hemostatic candidate for improving hemostasis in critical situations.
Functional surfaces and polymers with branched structures have a major impact on physicochemical properties and performance of membrane materials. With the aim of greener approach for enhancement of permeation, fouling resistance and detrimental heavy metal ion rejection capacity of polyetherimide membrane, novel grafting of poly (4-styrenesulfonate) brushes on low cost, natural bentonite was carried out via distillation-precipitation polymerisation method and employed as a performance modifier. It has been demonstrated that, modified bentonite clay exhibited significant improvement in the hydrophilicity, porosity, and water uptake capacity with 3 wt. % of additive dosage. SEM and AFM analysis showed the increase in macrovoides and surface roughness with increased additive concentration. Moreover, the inclusion of modified bentonite displayed an increase in permeation rate and high anti-irreversible fouling properties with reversible fouling ratio of 75.6%. The humic acid rejection study revealed that, PEM-3 membrane having rejection efficiency up to 87.6% and foulants can be easily removed by simple hydraulic cleaning. Further, nanocomposite membranes can be significantly employed for the removal of hazardous heavy metal ions with a rejection rate of 80% and its tentative mechanism was discussed. Conspicuously, bentonite clay-bearing poly (4-styrenesulfonate) brushes are having a synergistic effect on physicochemical properties of nanocomposite membrane to enhance the performance in real field applications.
A recent study by Ooi and Ooi (EH Ooi, ET Ooi, Mass transport in biological tissues: Comparisons between single- and dual-porosity models in the context of saline-infused radiofrequency ablation, Applied Mathematical Modelling, 2017, 41, 271-284) has shown that single-porosity (SP) models for describing fluid transport in biological tissues significantly underestimate the fluid penetration depth when compared to dual-porosity (DP) models. This has raised some concerns on whether the SP model, when coupled with models of radiofrequency ablation (RFA) to simulate saline-infused RFA, could lead to an underestimation of the coagulation size. This paper compares the coagulation volumes obtained following saline-infused RFA predicted based on the SP and DP models for fluid transport. Results showed that the SP model predicted coagulation zones that are consistently 0.5 to 0.9 times smaller than that of DP model. This may be explained by the low permeability value of the tissue interstitial space, which causes the majority of the saline to flow through the vasculature. The absence of fluid flow tracking in the vasculature in the SP model meant that any flow of saline into the vasculature is treated as losses and do not contribute to the saline penetration depth of the tissue. Comparisons with experimental results from the literature revealed that the DP models predicted coagulation zone sizes that are closer to the experimental values than the SP models. This supports the hypothesis that the SP model is a poor choice for simulating the outcome of saline-infused RFA.
A layered nanoreactor (zinc hydroxide gallate/nitrate nanohybrid) has been designed as a nano-vessel to confine the gallate/nitrate reaction inside zinc hydroxide layers for production of metal/nitrogen-doped carbon catalysts. Metals (Fe2+, Co2+ and Ni2+) doped and bare zinc hydroxide nitrates (ZHN) were synthesized as the α-phase hydroxide hosts. By an incomplete ion-exchange process, nitrate anions between the layers of the hosts were then partially replaced by the gallate anions to produce the layered nanoreactors. Under heat-treatment, the reaction between the remaining un-exchanged nitrate anions and the organic moiety inside the basal spacing of each nanohybrid plate resulted in obtaining highly porous 3D metal/nitrogen-doped carbon nanosheets. These catalysts were then used as extremely efficient electrocatalysts for catalyzing oxygen reduction reaction (ORR). This study is intended to show the way to get maximum electrocatalytic activity of the metal/N-doped carbon catalysts toward the ORR. This exceptionally high ORR performance originates from the increased available surface, the best pore size range and the uniform distribution of the active sites in the produced catalysts, all provided by the use of new idea of the layered nanoreactor.
In current practice, oil palm frond leaflets and stems are re-used for soil nutrient recycling, while the petioles are typically burned. Frond petioles have high commercialization value, attributed to high lignocellulose fiber content and abundant of juice containing free reducing sugars. Pressed petiole fiber is the subject of interest in this study for the production of lignocellulolytic enzyme. The initial characterization showed the combination of 0.125 mm frond particle size and 60% moisture content provided a surface area of 42.3 m2/g, porosity of 12.8%, and density of 1.2 g/cm3, which facilitated fungal solid-state fermentation. Among the several species of Aspergillus and Trichoderma tested, Aspergillus awamori MMS4 yielded the highest xylanase (109 IU/g) and cellulase (12 IU/g), while Trichoderma virens UKM1 yielded the highest lignin peroxidase (222 IU/g). Crude enzyme cocktail also contained various sugar residues, mainly glucose and xylose (0.1-0.4 g/L), from the hydrolysis of cellulose and hemicellulose. FT-IR analysis of the fermented petioles observed reduction in cellulose crystallinity (I900/1098), cellulose-lignin (I900/1511), and lignin-hemicellulose (I1511/1738) linkages. The study demonstrated successful bioconversion of chemically untreated frond petioles into lignin peroxidase and xylanase-rich enzyme cocktail under SSF condition.
Aluminium foam tube is a metal that consists of porous medium with special characteristics such as good energy absorption, good heat transfer and high thermal conductivity. These make it suitable to be used in a wide range of applications such as in heat exchangers. The aim of this project is to identify and analyse mechanical behaviour and microstructure aluminium foam tube produced and fabricated with infiltration method with vacuum-gas. The density of aluminium foam tube was also determined and an average aluminium foam tube with porosity 50% - 80% with the average NaCl particle size 2mm, 3mm and 4mm was produced. Foams with porosity 60%-75% NaCl has higher energy absorption. These was based on foam structure, density and maximum compressive load test result.
The volume of waste generated from surface coating industries is of global concern. The disposal of this waste in the form of effluent has put enormous pressure on land and also poses as a health hazard when it leaches into soil and underground water. The study aims to examine the utilization of vinyl acetate effluents from water based paint factories as an admixture in concrete. Concrete specimens containing 0%, 2.5%, 5% and 10% of vinyl acetate effluents by weight of cement were prepared. The specimens were tested for drying shrinkage for 28 days and porosity was tested using mercury intrusion porosimetry. Findings show that concrete containing various proportions of vinyl acetate effluents manifests higher shrinkage behaviour compared to the control item. An investigation of pore size distribution reveals that polymer effluents have particles size larger than 50 nm which are categorize as macroporous in accordance to IUPAC classification. It can be concluded that adding polymer vinyl acetate effluents affects concrete deformation due to the condition of its pore structures. The utilization of this material may provide beneficial effect in terms of the durability performance of concrete and minimize environmental pollution.
Electrospinning is a simple and versatile technique to fabricate continuous fibers with diameter ranging from micrometers to a few nanometers. To date, the number of polymers that have been electrospun has exceeded 200. In recent years, electrospinning has become one of the most popular scaffold fabrication techniques to prepare nanofiber mesh for tissue engineering applications. Collagen, the most abundant extracellular matrix protein in the human body, has been electrospun to fabricate biomimetic scaffolds that imitate the architecture of native human tissues. As collagen nanofibers are mechanically weak in nature, it is commonly cross-linked or blended with synthetic polymers to improve the mechanical strength without compromising the biological activity. Electrospun collagen nanofiber mesh has high surface area to volume ratio, tunable diameter and porosity, and excellent biological activity to regulate cell function and tissue formation. Due to these advantages, collagen nanofibers have been tested for the regeneration of a myriad of tissues and organs. In this review, we gave an overview of electrospinning, encompassing the history, the instrument settings, the spinning process and the parameters that affect fiber formation, with emphasis given to collagen nanofibers' fabrication and application, especially the use of collagen nanofibers in skin tissue engineering.
A high-performance porous biochar adsorbent prepared by facile thermal pyrolysis of seaweed (Gelidiella acerosa) is reported. The textural characteristics of the prepared seaweed biochar (SWBC) and the performance in the adsorption of methylene blue (MB) dye were evaluated. The batch experiment for the adsorption of MB was conducted under different parameters, such as temperature, pH, and initial concentration of MB in the range of 25-400 mg/L. The developed SWBC exhibited a relatively high surface area, average pore size, and pore volume of 926.39 m2/g, 2.45 nm, and 0.57 cm3/g, respectively. The high surface area and pristine mineral constituents of the biochar promoted a high adsorption capacity of 512.67 mg/g of MB at 30 °C. The adsorption isotherm and kinetics data best fitted the Langmuir and pseudo-second-order equations. The results indicate that SWBC is efficient for MB adsorption and could be a potential adsorbent for wastewater treatment.
We aimed to compare clinical and pathological reactions towards locally synthesized bovine bone derived from hydroxyapatite (bone docosahexaenoic acid (dHA)) and commercially available porous polyethylene (Medpor®, Porex Surgical Incorporation, Georgia, USA) orbital implants in animal models. An experimental study was performed on 14 New Zealand white rabbits. Group A (n=7) was implanted with bovine bone dHA and group B (n=7) was implanted with Medpor®. Clinical examinations were performed on Days 1, 7, 14, 28, and 42 post-implantation. The implanted eyes were enucleated on Day 42 and were sent for pathological evaluation. Serial clinical examinations included urine color and odor; feeding and physical activity demonstrated normal wellbeing in all the subjects. Localized minimal infection was observed in both groups during the first two weeks following implantation, and the subjects responded well to topical moxifloxacin. Both groups exhibited evidence of wound breakdown. No signs of implant migration or extrusion were observed in either group. The histopathological examination revealed no statistically significant difference in inflammatory cell reactions and fibrovascular tissue maturation between both types of implants. However, all (100%) of the bovine bone dHA implants displayed complete fibrovascular ingrowth compared to Medpor® implants (57.1%) at six weeks post-implantation (p=0.001). In conclusion, bovine bone dHA and Medpor® orbital implants were well-tolerated clinically and displayed similar inflammatory reactions and fibrovascular tissue maturation. Locally synthesized bovine bone dHA orbital implants displayed significantly greater complete fibrovascular ingrowth in comparison with Medpor® implants.
Epoxy shape memory foam (ESM) was produced by an advanced aqueous method. Mixture of epoxy, sodium bicarbonate,
hardener and ammonium chloride was premixed and emulsified in distilled water by using high speed stirring (at 1200
rpm). The content of sodium bicarbonate used was 5, 10, 15 and 20 phr. Besides that, ammonium chloride was used
(based on stoichiometrical content) to also function as acidifying agent in initiating the decomposition process of sodium
bicarbonate at lower foaming temperature. The foam morphology was observed using SEM. It was found that higher
sodium bicarbonate produced more porosity, more cell size, thinner cell wall and more cell interconnection. Epoxy shape
memory foam with 10 phr of sodium bicarbonate exhibited good shape memory property and better compression set.
Shape memory behaviour was measured by the recovered time of the transformed sample to its original shape.
A well-known planting medium in soilless culture is a coconut based material famously known in Malaysia as cocopeat.
It is a viable ecologically friendly peat soil substitute for containerized crop production. The multipurpose growing media
had received much interest particularly in commercial applications. This study focused on the physical and hydraulic
characteristics of cocopeat perlite mixture as a growing media in containerized plant production. Perlite was added to
cocopeat at a ratio of 3 cocopeat: 1 perlite. Bulk density, particle density, porosity, particle size distribution, water holding
capacity, wettability and hydraulic conductivity of the media were evaluated. About 82.93% of the total particles were
in the range between 0.425 and 4 mm in diameter at a bulk density of 0.09 g/cm3
. Total porosity (79%) and wettability
improved with the incorporation of perlite to cocopeat. This study showed that water holding capacity was very high at
912.54% whereas the saturated hydraulic conductivity was low at 0.1 cm/s. The results showed that adding perlite to
cocopeat had improved the physical and hydraulic characteristics of the media.
An advanced electrodialysis fermentation system was set up to remove ammonium during hydrogen fermentation. When the voltage was increased from 0 to 6 V, the average ammonium removal rate was improved from 8.7 to 31.1 mg/L/h at an initial ammonium concentration of 3000 mg/L. A model based on the Nernst-Plank equation and porous media properties of ion exchange membranes was successfully implemented to predict the ammonium removal performance. When such a system was fed with synthetic wastewater at an ammonium concentration of 3000 mg/L for hydrogen fermentation, a significant increase in specific hydrogen yield was observed in the experiment group at 4 V. Specific hydrogen yield was 225.0 mL/g glucose, this value is 47.9% higher than the control. Moreover, ammonium concentration in experiment group was reduced to 701.6 mg/L at 72 h when voltage was set at 4 V, which is 63.7% lower than that in 0 V experiment group.
This article demonstrates the first application of a copper-based porous coordination polymer (BTCA-P-Cu-CP) as a carbon paste electrode (CPE) modifier for the detection of malathion. The electrochemical behavior of BTCA-P-Cu-CP/CPE was explored using cyclic voltammetry (CV) while chrono-amperometry methods were applied for the analytical evaluation of the sensor performance. Under optimized conditions, the developed sensor exhibited high reproducibility, stability, and wide dynamic range (0.6-24 nM) with the limits of detection and sensitivity equal to 0.17 nM and 5.7 µAnMcm-1, respectively, based on inhibition signal measurement. Furthermore, the presence of common coexisting interfering species showed a minor change in signals (<4.4%). The developed sensor has been applied in the determination of malathion in spiked vegetable extracts. It exhibited promising results in term of fast and sensitive determination of malathion in real samples at trace level with recoveries of 91.0 to 104.4%. (RSDs < 5%, n = 3). A comparison of the two studied techniques showed that the HPLC technique is unable to detect malathion when the concentration is lower than 1.8 µM while 0.006 µM is detected with appropriate RSDs 0.2-5.2% (n = 3) by amperometric method. Due to the high sensitivity and selectivity, this new electrochemical sensor will be useful for monitoring trace malathion in real samples.