Optimization of adsorption conditions of papain on dye affinity membrane using response surface methodology

Statistical Design and Optimization of Cr (VI) Adsorption onto Native and HNO3/NaOH Activated Cedar Sawdust Using AAS and a Response Surface Methodology (RSM)

The removal of heavy metals from wastewater has become the subject of considerable interest at present. Thus, the use of novel adsorbents that are highly efficient is of critical importance for the removal of Cr (VI) ions from aqueous media. The adsorption of Cr (VI) ions from aqueous solutions by a new adsorbent, cedar wood sawdust, and the optimization of its adsorption parameters, were investigated in this study. Cedar wood sawdust was used in its native and HNO3/NaOH chemically modified forms as new low-cost sorbents to remove Cr (VI) ions from aqueous solutions in a batch system. The adsorption conditions were analyzed via response surface methodology. The RSM results showed that the optimal adsorption conditions yielding the best response were an adsorbent mass of 2 g for native Cedar and 1.125 g for its activated form, a metal concentration of 150 mg/L for native Cedar and 250 mg/L for activated, a temperature of 50 °C, a pH of 1, and a contact time of 67.5 min. At optimum adsorption conditions, the maximum adsorption capacities and the adsorption yields were 23.64 mg/g and 84% for native Cedar and 48.31 mg/g and 99% for activated Cedar, respectively.

Stoichiometrically Governed Curcumin Solid Dispersion and Its Cytotoxic Evaluation on Colorectal Adenocarcinoma Cells

Background

Colorectal cancer (CRC) is the third most commonly occurring cancer in men and the second most commonly occurring cancer in women. Curcumin (CMN) is obtained from a natural source and has no toxicity, even at high doses (8,000 mg/kg body weight in 24 hours) and was determined to have anticancer potency on several kinds of carcinoma. However, its medical applications were limited because of its low solubility and poor bioavailability.

Materials and Methods

To improve the medical applications of CMN, various hydrophilic carriers such as poloxamer 407 (PMX-407), poloxamer 188 (PMX-188), Gelucire 50/13 (Gel-50/13), and mannitol (MNL) were used to prepare a binary complex solid dispersion (SD). These binary SDs were characterized for aqueous solubility in various solvents. Physical stability, thermal behaviors, and morphology were determined by Fourier transform infrared spectrophotometric analysis, powder X-ray diffraction analysis, thermogravimetric analysis, differential scanning calorimetric analysis, scanning electron microscopy, dynamic light scattering study, and the novel dyeing test. In vitro drug release was determined by dissolution study. Based on the characterization, the better SD complex was optimized using Box-Behnken design (BBD). The cytotoxicity and apoptosis study of prepared CMN (C-SD) were used to test for colorectal adenocarcinoma cell lines.

Results

These results showed that the solubility of CMN is greatly improved after complexation with PXM-407 in SD. CMN is practically insoluble in water at acidic and neutral pH; however, the SD of CMN with PXM-407 produced significant improvement in solubility (1.266±0.0242 mg/mL) and dissolution (91.36±0.431% at 30 minutes); similarly, these data fit with a phase solubility study and in silico molecular modeling. Moreover, the solid-state characterization revealed that the SD complex exhibits the intermolecular hydrogen bond with drug and carrier. Also, the complex does not undergo any chemical modification owing to the amorphous form, and the dye test showed better coloring impact indicating the solubility of CMN. The cell cycle arrest confirmed at G2/M phase from flow cytometry analysis, and Western blot investigation was recognized molecular level cell death and the complex induced more exploit DNA during apoptosis.

Conclusion

This study confirmed that the ideal stoichiometric ratio of CMN with carrier to enhance its solubility was 1:1. This molecular complex of PXM-407 was found to be more effective against colorectal cancer (CRC) than pure CMN.

Pectin co-functionalized dual layered solid lipid nanoparticle made by soluble curcumin for the targeted potential treatment of colorectal cancer

The investigation is to increase the cytotoxicity of soluble curcumin (SC) by loading it onto pectin and skimmed milk powder (SMP) dual layered solid lipid nanoparticles (DL-SLN). The DL-SLN exhibited significantly higher encapsulation efficiency (83.94 ± 6.16), better stability (90 days), and sustained the drug release in different gastro intestional (GI) environments upto 72 h. Molecular docking revealed that the Vander Waals (57420.669 Kcal^-mol^-1) and electrostatic (-197.533) bonds were involved in the DL-SLN complex formation. The in vivo toxicity of DL-SLN was performed by the zebrafish model, the cell cycle arrest at G₂/M phase (64.34 %) by flow cytometry, and western blot investigation was recognized molecular level cell death using SW480 cells. Pharmacokinetic (PK) evaluation (Cmax-5.78 ± 3.26 μg/mL; Tmax-24 h) and organ distribution studies confirmed that the co-functionalized pectin based SLN could efficiently improve the oral bioavailability (up to 72 h) of curcumin (CMN) on colon-targeted release.

Microwave-assisted extraction, characterization and immunomodulatory activity on RAW264.7 cells of polysaccharides from Trichosanthes kirilowii Maxim seeds

Microwave-assisted extraction of polysaccharides from Trichosanthes kirilowii Maxim seeds (TKMSP) was optimized using Response surface methodology (RSM) base on Central composite design (CCD). The optimum extraction conditions are detailed as follows: liquid-solid ratio 42 mL/g, extraction temperature 80 °C, microwave power 570 W, extraction time 26 min. Under this conditions, the mean value of TKMSP yield 2.43 ± 0.45% (n = 3), which was consistent closely with the predicted value (2.44%). The five polysaccharides (TKMSP-1, TKMSP-2, TKMSP-3, TKMSP-4 and TKMSP-5) were isolated from TKMSP by DEAE-52. TKMSP-1, TKMSP-2 and TKMSP-4 were common in containing Man, Rib, Rha, GluA, GalA, Glu, Gal, Xyl, Arab and Fuc. However, there was no Fuc in TKMSP-3, while TKMSP-5 lacked GluA, GalA and Fuc. UV–vis and FT-IR analysis combined with molecular weight determination further indicated that the five fractions were polydisperse polysaccharides. A significant difference was achieved in the structural characterization of these five fractions. TKMSP exhibited immunosuppressive activity on RAW264.7 cells. It can be applied as a potential immunosuppressant agent in medicine.

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Microwave-assisted extraction of TKMSP optimized by RSM base on CCD.

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The five polydisperse polysaccharides were isolated from TKMSP.

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The structure characterizations of the five polysaccharides were analyzed.

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TKMSP-3 exhibited significant inhibition of RAW264.7 proliferation.

Changes in the Physical Properties of Calcium Alginate Gel Beads Under a Wide Range of Gelation Temperature Conditions

Until now, most studies using calcium alginate gel (CAG) have been conducted primarily at room temperature (20 °C) without considering gelation temperature. Moreover, the effects of gelation temperature on the physical properties of CAG beads have not been studied in detail. We aimed to study the effect of gelation temperature on the physical properties (diameter, sphericity, and rupture strength) of CAG beads. Response surface methodology was used in this study. The independent variables were sodium alginate concentration (X₁, 1.2–3.6%, w/v), calcium lactate concentration (X₂, 0.5−4.5%, w/v), gelation temperature (X₃, 5–85 °C), and gelation time (X₄, 6–30 min). Diameter (Y₁, mm), sphericity (Y₂, %), and rupture strength (Y₃, kPa) were selected as the dependent variables. A decrease in gelation temperature increased the diameter, sphericity and rupture strength of the CAG beads. Additionally, the CAG beads prepared at 5 °C exhibited the highest rupture strength (3976 kPa), lowest calcium content (1.670 mg/g wet), and a regular internal structure. These results indicate that decreasing the gelation temperature slows the calcium diffusion rate in CAG beads, yielding a more regular internal structure and increasing the rupture strength of the beads.

Optimization of polyvinylidene fluoride (PVDF) membrane fabrication for protein binding using statistical experimental design

Statistical experimental design was employed to optimize the preparation conditions of polyvinylidenefluoride (PVDF) membranes. Three variables considered were polymer concentration, dissolving temperature, and casting thickness, whereby the response variable was membrane-protein binding. The optimum preparation for the PVDF membrane was a polymer concentration of 16.55 wt%, a dissolving temperature of 27.5°C, and a casting thickness of 450 µm. The statistical model exhibits a deviation between the predicted and actual responses of less than 5%. Further characterization of the formed PVDF membrane showed that the morphology of the membrane was in line with the membrane-protein binding performance.

Adsorption of safranin-O dye on CO2neutralized activated red mud waste: process modelling, analysis and optimization using statistical design

Neutralization of red mud using CO₂and activated by calcined at 500 °C.

Optimization by Response Surface Methodology of the adsorption of Coomassie Blue dye on natural and acid-treated clays

The effect of acid treatment on natural agalmatolite (AN) and natural kaolinite (KN) was investigated, together with the influence of those modifications on the removal of Coomassie Blue (CB) dye. The process was optimized using the Response Surface Methodology (RSM) developed by the application of the quadratic model associated with the Central Composite Design. Adsorption was promoted by initial CB concentration of 25 mg L(-1), pH 2 and adsorbent mass of 0.1 g. The adsorption kinetics study carried out in optimized conditions established that the equilibrium times were 1 h for AN and AA (treated agalmatolite), 4 h for KN and 2 h for KA (treated kaolinite). The kinetics data for AN, KN and KA were best fitted to the pseudo second order model, whilst for AA, the result pointed to the pseudo first order model. In the isotherm of adsorption the maximum quantities were obtained with reference to 11.29 mg g(-1), 9.84 mg g(-1), 22.89 mg g(-1) and 30.08 mg g(-1) for the samples AN, AA, KN and KA respectively. The data fitting showed that the Sips model was the most satisfactory for all the adsorbents. The calculated thermodynamic parameters showed that the process was spontaneous in all the adsorbents, endothermic for the KN and KA samples, exothermic for AN and AA, involved the disorganization of the adsorption system for the KN and KA and its organization for the AN and AA samples. The results showed that the KN and KA samples were more appropriate for use as adsorbents.

Partitioning Behavior of Papain in Ionic Liquids-Based Aqueous Two-Phase Systems

This paper attempts to study and optimize the affinity partitioning conditions of papain in an aqueous two-phase system (ATPS). The effect of the amount of ionic liquids (ILs), the concentration of K2HPO4, temperature, pH, and the volume of papain solution were discussed concretely. The optimum conditions were determined as ionic liquid was 1.4 g and K2HPO4was 1.4 g, the extraction efficiency of papain could reach 98.33% with pH unadjusted. The temperature and the pH of the solution are major parameters that influence the partitioning of protein in ILs-based ATPSs. The partition of papain to the IL-rich phase was enhanced by increasing the amount of ILs, the concentration of K2HPO4, and temperature, especially at its isoelectric point.

Optimization of operating parameters for sludge process reduction under alternating aerobic/oxygen-limited conditions by response surface methodology

Batch tests were employed to estimate the optimal conditions for excess sludge reduction under an alternating aerobic/oxygen-limited environment using response surface methodology. Three key operating parameters, initial mixed liquor suspended solids (initial MLSS), HRT (hydraulic retention time) and reaction temperature (T), were selected, and their interrelationships studied by the Box-Behnken design. The experimental data and ANOVA analysis showed that the coefficient of determination (R(2)) was 0.9956 and the adjR(2) was 0.9912, which demonstrates that the modified model was significant. The optimum conditions were predicted to give a maximal ΔMLSS yield of 226 mg/L at an initial MLSS of 10,021 ± 50 mg/L, an HRT of 9.1h and a reaction temperature of 29°C. The prediction was tested by triplicate experiments, where a ΔMLSS yield of 233 mg/L was achieved under the chosen optimal conditions. This excellent correlation between the predicted and measured values provides confidence in the model.

Application of response surface analysis for biodegradation of azo reactive textile dye using Aspergillus foetidus

This paper reports the application of experimental design methodology for the optimization of decolourization of azo reactive textile dye Remazol Red RR and reduction of chemical oxygen demand (COD) using fungal isolate Aspergillus foetidus. Response surface methodology (RSM), involving central composite design matrix in three most important input variables; temperature, pH and initial dye concentration was employed. A total of 20 experiments were conducted in the study towards the construction of a quadratic model. This demonstrated the benefits of approach in achieving excellent predictions, while minimizing the number of experiments required. Very high regression coefficient between the variables and the responses indicated excellent evaluation of experimental data. Under optimized conditions fungal isolate was capable to decolourize Remazol Red RR up to 86.21% and COD reduction up to 55.43% was achieved during the experimental setup. Enzymatic activity indicated excellent outcome under the optimal process conditions. The experimental values agreed with the predicted ones, indicating suitability of the model and success of RSM approach in optimizing the process.

Purification and in situ immobilization of papain with aqueous two-phase system

Papain was purified from spray-dried Carica papaya latex using aqueous two-phase system (ATPS). Then it was recovered from PEG phase by in situ immobilization or preparing cross-linked enzyme aggregates (CLEAs). The Plackett-Burman design and the central composite design (CCD) together with the response surface methodology (RSM) were used to optimize the APTS processes. The highly purified papain (96–100%) was achieved under the optimized conditions: 40% (w/w) 15 mg/ml enzyme solution, 14.33–17.65% (w/w) PEG 6000, 14.27–14.42% (w/w) NaH₂PO₄/K₂HPO₄ and pH 5.77–6.30 at 20°C. An in situ enzyme immobilization approach, carried out by directly dispersing aminated supports and chitosan beads into the PEG phase, was investigated to recover papain, in which a high immobilization yield (>90%) and activity recovery (>40%) was obtained. Moreover, CLEAs were successfully used in recovering papain from PEG phase with a hydrolytic activity hundreds times higher than the carrier-bound immobilized papain.