Zero-order Model Research Articles

Reaction kinetics of aspalathin degradation and flavanone isomer formation in aqueous model solutions: Effect of temperature, pH and metal chelators

The poor stability of aspalathin in aqueous solutions is a major challenge in delivering a shelf-stable ready-to-drink (RTD) green rooibos iced tea. The kinetics of aspalathin degradation and the formation of eriodictyol glucoside isomers [(S/R)-6-β-D-glucopyranosyleriodictyol and (S/R)-8-β-D-glucopyranosyleriodictyol] in aqueous buffers were modeled to understand and predict aspalathin losses during heat processing. The effects of temperature and pH on the rate constants of aspalathin degradation and eriodictyol glucoside isomer formation were determined in a 0.1 M phosphate buffer with 5.7 mM citric acid. The zero-order model best described the reaction kinetics of aspalathin degradation and eriodictyol glucoside isomer formation. Increasing the temperature and pH increased the reaction rate constants. The activation energies of the reactions were much lower at pH 6 than at pH 4, indicating that pH affected the temperature dependence of the reactions. The 8-C-glucosyl eriodictyol derivatives (RE8G and SE8G) formed at much lower rates than the 6-C-glucosyl eriodictyol derivatives (RE6G and SE6G). The metal chelators, citric acid, citrate and EDTA, drastically reduced the reaction rate constants, indicating the catalytic role of metal ions in aspalathin autoxidation. The results of the study could assist manufacturers to improve the shelf life of rooibos RTD beverages by changing the formulation and adjusting heat processing conditions.

Kinetic approach to assess germination and growth parameters in 'Azkan' chickpea (Cicer arietinum L.) seeds during postharvest storage

This research aimed to investigate the impact of varying storage temperature (5-, 10-, 15- and 20 °C) and storage duration (0-, 60-, 120-, 180-, 240-, 300-, 360-, 420-, 480- and 540-days) on moisture contents, germination parameters (germination rate, mean germination time, germination speed, seed vigor index, germination energy and electrical conductivity) and growth parameters (shoot length, root length, shoot fresh weight, shoot dry weight, root fresh weight and root dry weight) of chickpea (Cicer arietinum L.) seeds. In addition, it is aimed to determine the optimum storage temperature by applying kinetic model and multivariate analysis to these parameters. During germination, the tested parameters presented differential sensitivity to both storage temperature and duration. Seeds at a temperature of 20 °C were more affected than at 5, 10 and 15 °C. The storage at 20 °C reduced germination and growth parameters. It also caused an increase in electrical conductivity values, which decreased the viability of the seed and in the germination rate. The zero-order kinetic model was determined as the most suitable model for germination and growth parameters, and half-life and activation energy were determined accordingly. Based on the results obtained from the zero-order kinetic model, it can be suggested that the optimal storage temperature for maintaining seed quality is 5 and 10 °C.

Exploring the mystery of soil carbon mineralization: Insights from incubation experiments and kinetic modeling

Soil carbon mineralization is vital for carbon sequestration but affected by factors like soil type and residue quality. Understanding the process and factors is still incomplete, including the interplay between soil properties and organic residues and the need for accurate kinetic models. Research faces significant challenges in describing carbon mineralization dynamics. The present study aimed to investigate carbon mineralization in three soils located in Tamil Nadu, India (S1, S2 and S3) that possess distinct textures. The study also focused on the effects of five different plant residues (Rice, maize, sugarcane, cotton and turmeric) on carbon mineralization in these soils. Incubation experiments were conducted for 150 days, and CO2 evolution was measured at different time intervals of 7, 10, 15, 30, 60, 90, 120 and 150 days. The performance of three kinetic models (Zero order model, exponential kinetic model and first order model) was also evaluated in predicting carbon mineralization using experimental data. The results showed that the rate and extent of carbon mineralization varied significantly among the different soils and residues. The highest carbon mineralization was observed in rice (989.02 µg C/g/day) and maize (966.53 µg C/g/day) residue, while the lowest was in sugarcane (752.09 µg C/g/day) residue. Among the kinetic models, the first-order kinetic model provided the best fit for all treatments (R2=0.98). The findings suggest that soil texture and residue quality play crucial roles in carbon mineralization. The first order kinetic model can be useful for predicting carbon mineralization in different soil-residue systems. These results have implications for managing soil carbon sequestration and mitigating climate change.

Dopamine / Artesunate loaded polyhydroxybutyrate-g-cellulose- magnetite zinc oxide core shell nanocomposites: Synergistic antimicrobial and anticancer efficacy

In this study, polyhydroxybutyrate-g-cellulose - Fe3O4/ZnO (PHB-g-cell- Fe3O4/ZnO) nanocomposites (NCs) was synthesized and used as a delivery system for Dopamine (DO) /Artesunate (ART) drugs. Different types of cells (Ccell, Scell, Pcell) grafted with PHB were designed and mixed with different contents of Fe3O4/ZnO. Physical and chemical features of PHB-g-cell-Fe3O4/ZnO NCs were detected by FTIR, XRD, dynamic light scattering, transmission electron microscopy, and scanning electron microscopy. ART/DO drugs were loaded into PHB-g-cell- Fe3O4/ZnO NCs by single emulsion technique. The rate of drugs release was studied at different pHs (5.4, 7.4). Owing to the overlap between the absorption bands of both drugs, differential pulse adsorptive cathodic stripping voltammetry (DP-AdCSV) was used for the estimation of ART. To study the mechanism of ART and DO release, zero-order, first order, Hixon Crowell, Higuchi and Korsmeyer-Peppas models were applied to the experiment results. The results showed that Ic50 of ART @PHB-g-Ccell-10% DO@ Fe3O4/ZnO, ART @PHB-g-Pcell-10% DO@ Fe3O4/ZnO and ART @PHB-g-Scell-10% DO@ Fe3O4/ZnO were 21.22, 12.3, and 18.11 μg/mL, respectively. The results revealed that ART @PHB-g-Pcell-10% DO@ Fe3O4/ZnO was more effective against HCT-116 than the carriers loaded by a single drug. The antimicrobial efficacy of the nano-loaded drugs was considerably improved compared with free drugs.

The correlation among residual nitrites, biogenic amines, N-nitrosamine formation, and degradation occurrence of punicalagin α/β, rosmarinic acid, carnosol, and carnosic acid in extract-treated sausage during storage.

The aim of this study was to investigate the relation between residual α- and β-punicalagin in Punica granatum L.; PPE and rosmarinic acid, carnosol, and carnosic acid in Salvia eremophila (SE) with residual nitrites, biogenic amines (cadaverine, putrescine, and histamine), N-nitrosodimethylamine (NDMA), microbial counts, lipid oxidation indices, and color values in extract-treated sausage over 14 days of storage. Sausage containing SE + nitrite 60 ppm (SSN) showed minimum levels of the residual nitrites (13.14 mg/kg), NDMA (0.74 ± 0.05 μg/kg), and biogenic amine (histamine, 1.8 mg/kg; cadaverine, 3.7 mg/kg; and putrescine, 4.3 mg/kg) due to retarded degradation rate of 285.84-216.44 mg/kg; rosmarinic acid, 41.62-33.16 mg/kg; carnosol, and 88.70-76.73 mg/kg; carnosic acid over storage time. The first-order kinetic model fitted well for the degradation of rosmarinic acid and carnosol acid in SSN sample. TBA value remained below the threshold limit (0.32 mg kg-1) through 14 days for SSN. Second-order and zero-order reaction models had the best agreement with sausages' PV and TBA values, respectively. After 2 weeks of storage, E. coli and Cl. perfringens counts in the SN120 (sausage containing 120 ppm nitrite) and SSN were significantly lower than the other samples (p < .05), with the values 2.1 and 1.5 log cfu/g for SN120 and 2.2 and 1.6 log cfu/g for SSN formulation. Conversely, oxidation indices, residual nitrites, NDMA, and biogenic amine increased in sausage samples containing PPE extracts (SPN) owing to total degradation of α- and β-punicalagin during storage. The results indicated that SE can be used as potential co-preservative by reducing the levels of required nitrite in food industry.

Development of a potential carrageenan-based hard capsule as the alternative of conventional capsules by implementing the oligomerization reaction

Carrageenan-based (CRG) hard capsules have a slower disintegration rate compared to that of gelatin capsules. Therefore, there is an urgent need to optimize the performance of this material using the oligomerization process. The preparation was conducted by oligomerizing CRG, cross-linking it with maltodextrin (MD), and plasticizing it with sorbitol (SOR). Based on our research, we found that the capsule prepared with the code CRG(O)-MD/SOR had an ash content of 11.80% and a water content of 17.20 ± 1.20 %. No microbes or yeast were found in the capsule, and only negligible amounts of heavy metal traces were present. Scanning electron microscopy (SEM) morphology analysis of the capsule surface showed that no pores were observed, even at a magnification of 10,000 times. This result was supported by the BET-BJH analysis, which showed that the pores had an average diameter of 49.26 Ǻ. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed that the Tg of the prepared capsules was at 51.4 °C. Fourier-transform infrared spectroscopy (FTIR) analysis showed that the presence of citric acid as the oligomerization agent had changed the chain composition of the carrageenan. Acute toxicity analysis showed that the capsule was safe even at a dose of 3,000 mg/bw. The Young's modulus of CRG(O)-MD/SOR was determined to be 1.500 ± 0.52 MPa. In vitro disintegration testing of CRG(O)-MD/SOR showed that the capsule required 20.01 ± 1.13 mins, 23.13 ± 1.14 mins, and more than 120 mins to disintegrate at pH 1.2, 4.5, and 6.8, respectively. Release kinetics analyses showed that the drugs paracetamol (PCT) and salicylamide (SCA) followed the zeroth-order model at pH 1.2 and 4.5, while they were best described by the Peppas-Sahlin model at pH 6.8. Finally, the maximum swelling degree of the CRG(O)-MD/SOR hard capsule was determined to be 708.88%, which was reached in 15.22 mins. This capsule has the potential to be used as an alternative to conventional hard capsules on a broader scale. Furthermore, this work supports Sustainable Development Goals (SDGs) point 3, good health and well-being, by providing a capsule made from biomaterial.

Myrtle (Eugenia gracillima Kiaersk.) as a fermented alcoholic beverage alternative to wine: Preliminary study

Myrtle (Eugenia gracillima Kiaersk.) is an underexploited fruit rich in bioactive compounds. It can be consumed fresh or processed into diverse products. This preliminary study aimed to develop myrtle-based fermented alcoholic beverages and evaluate the effects of different concentrations of total soluble solids (TSS), in which B1 (15 °Bx) and B2 (20 °Bx). Fermentation kinetics, fermentation yield, alcohol yield, productivity, physicochemical, phytochemical and color properties were determined. In addition, color degradation kinetics and correlation analyze (significant phytochemical and color parameters) were performed. A second-order polynomial model provided a good fit to fermentation data (R2 > 0.95). Fermentation of myrtle must with a lower TSS content resulted in higher fermentation yield (60.00%) and provided a beverage whose physicochemical parameters were within regulatory limits. Myrtle beverages were excellent sources of phenolic compounds (3478.66–3783.04 mg gallic acid equivalents 100 g−1). The beverage with higher TSS had a significantly stronger color (p ≤ 0.05). Color degradation kinetics were described by first-order (B1) and zero-order (B2) models, which revealed that redness (a*) was the most sensitive color parameter. There was a significant negative correlation (p ≤ 0.05) of most color parameters with phenolic compounds values, indicating that darker colored formulations have higher content of these phytochemical compounds. Industrial production of alcoholic fermentation of myrtle beverages is feasible and may represent an interesting income source for small-scale producers.

Insight into direct phosphorus release from simulated wastewater ferric sludge: Influence of physiochemical factors

Phosphorous recovery from chemical phosphorus removal (CPR) plants is limited. CPR plants that use iron salts for phosphorous removal generate iron phosphate (Fe-P) rich sludge. This study investigates the influence of pH and competing anions (chloride), on phosphorus and soluble iron release from lab simulated Fe-P sludge. Factors influencing recovery, such as sludge age and Fe/P molar ratio are also investigated. Results showed that alkaline treatment of Fe-P sludge was not effective in releasing Fe (<3%) but effective in releasing P, particularly at controlled pH value of 10 where the %P release was (90 ± 2%). Sludge ageing time did not affect P release from Fe-P sludge at ages less than 5 days. However, a remarkable decrease in %P release (i.e., 50% reduction) was observed at ages of 9 and 11 days for pH values of 9–10. Arsenic extraction of exchangeable surface bound P from Fe-P sludge and surface area determination of hydrous ferric oxide (HFO) under different aging times supported qualitatively the internalization of surface bound P during aging, which is a proposed mechanism responsible for the decrease in P release for older sludge. Chloride effect in releasing P from Fe-P sludge was negligible. The reduction in P release by aging was best described by a zero-order kinetic model. Modeling with the PHREEQC geochemical software did not always agree with the measured release of phosphorus from the Fe-P sludge. PHREEQC assumes all surface sites for phosphorus are exchangeable and has no mechanism to represent phosphorus trapped within HFO particles.

Bioremediation of propylbenzenes by a novel marine microalga Rhinomonas reticulata S6A isolated from Daya Bay: acute toxicity, growth kinetics and biodegradation performance

This study investigated the degradation characteristics of propylbenzenes (PBZs, including isopropylbenzene and n-propylbenzene), with high leakage risks and ecological hazards, by a newly isolated marine microalga named Rhinomonas reticulata S6A which is a promising candidate for eco-friendly bioremediation from marine. About 72% and 56% of n-PBZ and i-PBZ can be degraded after 7 days in culture. The acute toxicity of n-PBZ (96h - EC50 = 2.38 mg/L) was higher than that of i-PBZ (96h - EC50 = 3.65 mg/L). The growth inhibition kinetics of this strain were consistent with the Edwards model (R2 = 0.998) and Aiba model (R2 = 0.999). The optimal concentrations for the degradation of n-PBZ and i-PBZ were calculated to be 2.42 mg/L and 2.78 mg/L, respectively. The degradation trends of PBZs conformed to the zero-order kinetic model, and k increased with initial concentrations. The moderate increase in inoculation density could accelerate the degradation of PBZs, with the maximum specific growth rates (r) of 1.116/d (n-PBZ) and 1.230/d (i-PBZ) at the initial inoculation density of 104 cells/mL, while over-inoculation (initial microalgae density more than 105 cells/mL) was not conducive to the degradation of the pollutants. There is not much data on the biodegradation of PBZs in the aquatic environment, so it would be worthwhile to try to apply the new microalgae to explore the fate of PBZs.

Effect of copper, arsenic and nickel on pyrite-based autotrophic denitrification

Pyritic minerals generally occur in nature together with other trace metals as impurities, that can be released during the ore oxidation. To investigate the role of such impurities, the presence of copper (Cu(II)), arsenic (As(III)) and nickel (Ni(II)) during pyrite mediated autotrophic denitrification has been explored in this study at 30 °C with a specialized microbial community of denitrifiers as inoculum. The three metal(loid)s were supplemented at an initial concentration of 2, 5, and 7.5 ppm and only Cu(II) had an inhibitory effect on the autotrophic denitrification. The presence of As(III) and Ni(II) enhanced the nitrate removal efficiency with autotrophic denitrification rates between 3.3 [7.5 ppm As(III)] and 1.6 [7.5 ppm Ni(II)] times faster than the experiment without any metal(loid) supplementation. The Cu(II) batches, instead, decreased the denitrification kinetics with 16, 40 and 28% compared to the no-metal(loid) control for the 2, 5 and 7.5 ppm incubations, respectively. The kinetic study revealed that autotrophic denitrification with pyrite as electron donor, also with Cu(II) and Ni(II) additions, fits better a zero-order model, while the As(III) incubation followed first-order kinetic. The investigation of the extracellular polymeric substances content and composition showed more abundance of proteins, fulvic and humic acids in the metal(loid) exposed biomass.Graphical

Controlled drug delivery from chitosan-coated heparin-loaded nanopores anodically grown on nitinol shape-memory alloy

Nitinol (NiTi shape-memory alloy) is an interesting candidate in various medical applications like dental, orthopedic, and cardiovascular devices, owing to its unique mechanical behaviors and proper biocompatibility. The aim of this work is the local controlled delivery of a cardiovascular drug, heparin, loaded onto nitinol treated by electrochemical anodizing and chitosan coating. In this regard, the structure, wettability, drug release kinetics, and cell cytocompatibility of the specimens were analyzed in vitro. The two-stage anodizing process successfully developed a regular nanoporous layer of Ni-Ti-O on nitinol, which considerably decreased the sessile water contact angle and induced hydrophilicity. The application of the chitosan coatings controlled the release of heparin mainly by a diffusional mechanism, where the drug release mechanisms were evaluated by the Higuchi, first-order, zero-order, and Korsmeyer-Pepass models. Human umbilical cord endothelial cells (HUVECs) viability assay also showed the non-cytotoxicity of the samples, so that the best performance was found for the chitosan-coated samples. It is concluded that the designed drug delivery systems are promising for cardiovascular, particularly stent applications.

Metabolic Biodegradation Pathway of Fluoranthene by Indigenous Trichoderma lixii and Talaromyces pinophilus spp.

Two indigenous ascomycetes fungi, Trichoderma lixii strain FLU1 (TlFLU1) and Talaromyces pinophilus strain FLU12 (TpFLU12), were isolated from benzo(b)fluoranthene-enriched activated sludge and tested for bio-catalytically degrade fluoranthene as a sole carbon source. TlFLU1 and TpFLU12 degraded 98 and 99% of 400 mg/L of fluoranthene after 16 and 12 d incubation period, respectively. Degradation correlated with the upregulation of expression of ligninolytic enzymes. The GC-MS and FTIR analysis of the degradation products suggest that the degradation is initiated at the C1-C2 position of the compound ring via oxygenation and ring cleavage to form 9-oxo-9H-fluorene-1-carboxylic acid before undergoing ring cleavage to yield fluorenone, which then proceeds through the ß-Ketoadipate pathway via benzene-1,2,3-tricarboxylic acid. The degradation rate is better fitted in the first-order and zero-order kinetic model for TlFLU1 and TpFLU12, respectively. The metabolites from the TlFLU1 degradation media are shown to be toxic in Vibryo parahaemolyticus after 6 h of exposure with effective concentration (EC50) and toxicity unit (TU) values of 14.25 mg/L and 7.018%, respectively, while also being observed as non-toxic from TpFLU12 degradation media with an EC50 and TU values of 197.1 mg/L and 0.507%, respectively. Results from this study show efficient metabolism of fluoranthene into an innocuous state by TlFLU1 and TpFLU12.

Evaluation of redox activity of brownmillerite-structured Ca2Fe2O5 oxygen carrier for chemical looping applications

The brownmillerite-structured Ca2Fe2O5 oxygen carrier has shown its great potential in chemical looping processes, due to it can be completed regeneration in a H2O or CO2 atmosphere without the air reactor. However, the low reaction reactivity of Ca2Fe2O5 restricts its application. In this study, Ca2Fe2O5 oxygen carrier was prepared by sol-gel method. The reduction and oxidation kinetics of Ca2Fe2O5 were evaluated in H2 and CO2 atmospheres, respectively. The reduction of Ca2Fe2O5 in H2 atmosphere in good agreement with the random nucleation and growth model with Ea and A of 53.82 kJ/mol and 2.65 s−1, respectively. The dimension of the model increases with conversion (A1.5 → A2 → A3 → A4). The oxidation of reduced Ca2Fe2O5 in CO2 atmosphere can be described by the zero-order contraction model with Ea and A of 11.66 kJ/mol and 0.05 s−1, respectively. The kinetics analysis showed that both the reduction of H2 and the oxidation of CO2 are one-step reactions, as evidenced by the fact that only Fe0 and Fe3+ phases were detected in semi-in situ XRD analysis. It was inferred that the release and recovery of lattice oxygen is from inside to outside for Ca2Fe2O5 oxygen carrier in the redox process. By reducing the migration energy barrier of lattice oxygen between bulk and surface would be an effective means to improve the reactivity of Ca2Fe2O5 oxygen carriers.

Preparation of polymersomes from synthesized hyaluronic acid-graft-poly(ε-caprolactone) copolymers for drug delivery to the brain

The application of amphiphilic block copolymer for drug delivery has received immense attention in recent years. Polymersomes are favorable types of polymeric systems that can load different molecules and their structures and functional properties can be decorated for various drug-releasing platforms. Here, we represent a hyaluronic acid (HA) and polycaprolactone (PCL)-based amphiphilic block copolymer that can be assembled as polymersomes via the solvent substitution strategy. HA-graft-PCL copolymers were synthesized by a novel method, through the formation of an amide bond between the N-terminal amino acid of PCL and the carboxyl (–COOH) group in HA. Following the assemblage of copolymers, nanopolymersomes were coated with polysorbate-80 (P80) to target blood–brain barrier receptors. To determine the functional capacity of this vehicle, celecoxib (COXI) was loaded into nanopolymersomes. Then, particle size distribution, encapsulation efficiency, zeta potential, and polydispersity index were improved to 95%, 120 ± 10 nm, −21 mV, and ≤0.2, respectively. The P80-COXI-NPOL (P80 coated-COXI loaded-Nanopolymersomes) exhibited up to 72 h of sustained drug release in phosphate-buffered saline. Besides, the release profile revealed a biphasic pattern containing initial anomalous release (n = 0.63) in the first 9 h, followed by a linear pattern in 9–72 h (zero-order model). Overall, through targeted delivery of the encapsulated drug (COXI), these nanopolymersomes provide a passive targeting system to spot P80 receptors on the blood–brain barrier.

Estimation of coffee shelf life under accelerated storage conditions using mathematical models - Systematic review

The shelf life of a food product is a finite period after manufacturing and packaging, during which it retains a required and acceptable level of quality for consumption. The objective was to characterise and describe the transparent and comprehensible processing process to collect, select, critically evaluate and summarise available evidence regarding the use of mathematical models in the estimation of the shelf life of coffee under accelerated storage conditions. Of the 183 articles identified, nine studies were included in the review: four evaluated various types of packaging containing roasted and ground coffee, three coffee-based beverages, one infusion and one in bean format; the models frequently used were Weibull-Hazard Analysis, first-order, and zero-order kinetic model, which requires the decay kinetic constant, the same as that acquired by the Arrhenius model or a proposed model. Quality descriptors and mathematical models have been identified that allow estimating the shelf life of coffee and its derivative products under accelerated storage conditions, in addition to primary sources with experimental designs.

Dissociation Kinetics of Gaseous Ozone in Onion (Allium Cepa L.) Bulbs

ABSTRACT Ozone decomposition kinetics varies significantly in the presence of biological commodity. This variation depends on many factors but primarily on the active sites in agricultural commodities and storage environments. Ozone decomposition kinetics in onion bulbs at temperatures (2, 10, and 18°C) and relative humidity (RH) (35 & 85%) for different ozone concentrations (100, 200, 300 ppm) and number of exposures (1, 2, 3) were investigated. Zero-order, first-order, and second-order kinetic models were fitted to the ozone decomposition data with respect to time. It was found that the decomposition kinetics follows a first-order reaction and the decomposition rate constant ( k d ) varies from 1.712 × 10−3 s−1 − 5.181 × 10−3 s−1 in the presence of onion. The half-life period ( t 1 / 2 ) was found to increase with concentration and number of exposures and decrease with temperature and relative humidity. The activation energy was found to vary between 1.840 and 10.216 kJ mole−1 and 6.271–12.461 kJ mole−1 for the relative humidity of 85% and 35%, respectively.

A double-layered gastric floating tablet for zero-order controlled release of dihydromyricetin: Design, development, and in vitro/in vivo evaluation

Dihydromyricetin (DHM) is an important natural flavonoid. However, most of DHM preparations have shown shortcomings such as low drug loading, poor drug stability, and/or large fluctuations in blood concentration. This study aimed to develop a gastric floating tablet with a double-layered structure for zero-order controlled release of DHM (DHM@GF-DLT). The final product DHM@GF-DLT showed a high average cumulative drug release at 24 h that best fit the zero-order model, and had a good floating ability in the stomach of the rabbit with a gastric retention time of over 24 h. The FTIR, DSC, and XRPD analyses indicated the good compatibility among the drug and the excipients in DHM@GF-DLT. The pharmacokinetic study revealed that DHM@GF-DLT could prolong the retention time of DHM, reduce the fluctuation of blood drug concentration, and enhance the bioavailability of DHM. The pharmacodynamic studies demonstrated that DHM@GF-DLT had a potent and long-term therapeutic effect on systemic inflammation in rabbits. Therefore, DHM@GF-DLT had the potential to serve as a promising anti-inflammatory agent and may develop into a once-a-day preparation, which was favorable to maintain a steady blood drug concentration and a long-term drug efficacy. Our research provided a promising development strategy for DHM and other natural products with a similar structure to DHM for improving their bioavailability and therapeutic effect.

Optimisation of Encapsulation by Complex Coacervation of Phenolic Compounds from Propolis with Triumfetta cordifolia Gum and Kinetic Study

Phenolic compounds from propolis have pharmacological properties such as antioxidant, antidiabetic, antiulcer, anticancer. However, they are unstable and oxidize in contact with ultraviolet rays and humidity. In order to limit their oxidation, phenolic compounds need to be protected through a polymeric membrane. The aim of this work is to optimize the encapsulation of phenolic compounds from propolis by complex coacervation using a polymer matrix consisting of gelatin and a Cameroonian tropical gum named Triumfetta cordifolia. A second order regression using Central Composite Design (CCD) was used to determine the optimal conditions of encapsulation as follows: pH (X1) 4.2, gelatin concentration (X2) 54 % and active ingredient concentration (X3) 25 %. The use of Triumfetta cordifolia gum as an anionic polymer led to a considerable encapsulation rate of total polyphenols and flavonoids with the values of 85.75 % and 88.24 % respectively. Concerning the study of the release kinetic of phenolic compounds from propolis, it appeared that the zero-order model better fitted the release in the gastric environment with a high correlation coefficient of R2 = 0.99. While in the intestinal environment it was the first-order model which better explained their slowed diffusion into the solvent (R2= 0.97).

Low thermal pre-treatment of palm kernel expeller to enhance microalgal hydrogen production

The production of hydrogen from microalgae has inevitably intrigued considerable interests off late. However, the commercial production of microalgal hydrogen is not yet feasible due to the intricate production processes and expensive procedures. Therefore, this research work intended to streamline the microalgal hydrogen generation by utilizing the organic solid waste, palm kernel expeller (PKE), for converting into microalgal hydrogen. Accordingly, the impacts of low thermal pre-treatment method using hydrolysis process was studied at 50 °C, 70 °C, and 90 °C to overcome the recalcitrance of lignocellulosic PKE in associating with the rate of microalgal hydrogen production. The results evidenced that the maximum hydrogen yield was attained at 638 mL H2/g microalgae under the dark anaerobic environment whilst using PKE that was pre-treated at 90 °C for 4 h. In comparison with untreated PKE, this microalgal hydrogen yield had increased by two folds. The release of inhibitory compounds had increased significantly at 50 °C. Thereafter, the zeroth order model was employed to quantify the kinetics of microalgal hydrogen production. The highest rate was successfully achieved at 128 mL H2/g microalgae-d while subsisting on 90 °C pre-treated PKE for 4 h.

Biomimetic Silica Particles with Self-Loading BMP-2 Knuckle Epitope Peptide and Its Delivery for Bone Regeneration.

Biomimetic silica deposition is an in-situ immobilization method for bioactive molecules under biocompatible conditions. The osteoinductive P4 peptide derived from the knuckle epitope of bone morphogenetic protein (BMP), which binds to BMP receptor-II (BMPRII), has been newly found to contain silica formation ability. We found that the two lysine residues at the N-terminus of P4 played a vital role in silica deposition. The P4 peptide co-precipitated with silica during P4-mediated silicification, yielding P4/silica hybrid particles (P4@Si) with a high loading efficiency of 87%. P4 was released from P4@Si at a constant rate for over 250 h, representing a zero-order kinetic model. In flow cytometric analysis, P4@Si showed a 1.5-fold increase in the delivery capacity to MC3T3 E1 cells than the free form of P4. Furthermore, P4 was found anchored to hydroxyapatite (HA) through a hexa-glutamate tag, followed by P4-mediated silicification, yielding P4@Si coated HA. This suggested a superior osteoinductive potential compared to silica or P4 alone coated HA in the in vitro study. In conclusion, the co-delivery of the osteoinductive P4 peptide and silica by P4-mediated silica deposition is an efficient method for capturing and delivering its molecules and inducing synergistic osteogenesis.