response surface method

This study was conducted to produce probiotic cheese containing barley (Hordeum vulgare) bran, optimizing its physicochemical, rheological, and sensory characteristics while maximizing the viability of Lactobacillus acidophilus over a nine-day storage period at 4 °C.

Using the Response Surface Method (RSM), 13 treatment combinations were designed, including barely bran concentrations ranging from 0% to 4% and storage durations extending up to 42 days. Two types of cheese were evaluated: probiotic cheese and probiotic cheese containing barley bran. Comprehensive assessments included microbial viability, physicochemical variables (such as pH and acidity), rheological properties, and sensory evaluation.

The highest viability of probiotics, recorded at 8.7 log CFU/g, was observed in the probiotic low-fat cheese on day 1 with a barley bran concentration of 4%. The physicochemical analysis indicated suitable pH and acidity levels. Rheological characteristics, such as viscosity and hardness, were enhanced in barley bran samples, whereas adhesiveness showed no significant change. The color index (L*) decreased in the samples with added barley bran.

Incorporating 2.37% barley bran into the cheese formulation resulted in a product with optimal physicochemical, rheological, and sensory properties. In addition, the population of L. acidophilus bacteria increased to 8.21 log CFU/g, and these characteristics were maintained for approximately nine days during refrigerated storage (4 °C).

Considering the increased demand for cars in different countries during recent years, using car washes for washing vehicles has received a lot of attention. This study aimed to assess removing chemical oxygen demand (COD) from car wash effluent using the electrocoagulation method.

A reactor with dimensions of 40 cm * 50 cm * 50 cm of Plexiglas with a volume of 90 L equipped with an electric current generator and an electrode was used connected to the DC current generator in the form of Al-Al. The response surface method (RSM) was applied to optimize the factors affecting COD removal in the electrocoagulation process. For this purpose, D-optimal was utilized to optimize the experiments. The effects of measurable factors such as electrolysis time (X1), current density (X2), and aeration time (X3) were examined to check COD removal.

According to the results, the optimal operating conditions for COD removal during electrolysis (30 min) were as follow: the current density was 18.75 A/m2, and the aeration time of 30 min was 48.51%.

In conclusion, electrocoagulation is, to some extent, a reliable and environmentally compatible technique for car wash wastewater treatment.

Lamotrigine is widely used in the management of partial epilepsy, generalized tonic-clonic epilepsy and Lenox-Gastut syndrome and is an add-on therapy in the treatment of complex and simple partial seizures and secondarily generalized tonic-clonic seizures resistant to multiple drug therapy.

In the current study, a fluorometric nanoprobe based on metal–organic frameworks (MOF) was designed for the determination of lamotrigine in exhaled breath condensate (EBC). The MOF nanoprobe consisted of Tb3+ ions as metal part and dimethylformamide (DMF) and 1,10-phenanthroline (Phen) as organic parts of nanoprobe.

The used probe shows a weak fluorescence in alkaline media owing to an energy transfer from nitrogen groups of DMF and Phen on carbonyl group of DMF as an antenna for Tb3+ luminescence. However, its fluorescence is enhanced in acidic conditions by protonation of DMF nitrogen atoms and Phen and deactivation of energy transfer pathways of nitrogen groups to carbonyl group. Lamotrigine addition to this fluorescent system leads to quenching in the fluorescence intensity due to reactivation of the above mentioned energy transfer pathways resulting in competitive interaction with H+ ions. Moreover, the inner filter effect (IFE) of lamotrigine on DMF–Tb–Phen MOF NPs is considered as another reason for the observed quenching in the fluorescence of DMF–Tb–Phen MOF NPs. The intensity of the fluorescence was recorded at λem = 545 nm and the difference between fluorescence signal in the absence and presence of lamotrigine was the analytical response. The factors affected on experimental conditions were optimized utilizing a multivariate optimization technique. The validation of nanoprobe response to lamotrigine gives a linear relationship in the range of 0.05 to 2.0 µg⋅mL‒1 with a detection limit of 11.0 ng⋅mL‒1 for lamotrigine.

The developed method reveals good repeatability and selectivity for lamotrigine in real samples.

Canning food is one of the good methods of food preservation. This method will create a good shelf if the principles of preparation are observed. In this regard, the present study aimed to optimize the cooking time and pressure for canned beef production. In this study, three levels of pressure (1, 1.2 and 1.4 bars) and three cooking times (9, 15 and 18 minutes) were applied. Response surface method was used for pH, phloem weight, water-soluble solids (Brix), and protein content and sensory examinations in the produced products. The results showed that the phloem, weight and the general acceptance of the samples decreased with the increasing of processing time and pressure. Only the linear parameter of process time had a significant effect on the pH at the level of 5%, which increased slightly with the pH of the samples. The results of process optimization showed that the surface response method is an appropriate approach for optimizing the cooking process in the preparation of canned veal.

Sofosbuvir is a potent direct-acting antivirus agent that has been listed as a promising medicine for the treatment of all genotypes of hepatitis C virus. As antiviral drugs could be metabolized to their associated compounds and toxicologically and pharmacologically interfere with the parent drugs, identifying the therapeutic range of drugs would be notable.

In the current study, copper nanoclusters (Cu NCs) are synthesized during the reduction of copper nitrate with hydrazine hydrate in a protected media and used as a nanoprobe for the determination of sofosbuvir in plasma samples. Herein, synchronous fluorescence spectroscopy (SFS) is used for monitoring of fluorescence variation of nanoprobe owing to the excessive benefits compared with the traditional fluorescence.

SFS peak of Cu NCs has appeared at 355 nm with ∆λ=80 nm which is decreased in the presence of sofosbuvir. To optimize the reaction factors, a response surface methodology is used and in the optimized conditions, a linear concentration-response plot is obtained in a range of 0.05-6.0 µg mL−1 with a limit of detection of 0.0147 µg mL−1.

The developed method also reveals good repeatability and selectivity for sofosbuvir in plasma samples.

Although Green tea is a rich source of antioxidant, use of this herbal in food industries is limited due to its oxygen and light instabilities.

Green tea polyphenols were encapsulated into liposomes using Mozafari method (with no solvents and detergents) to improve bioavailability of tea polyphenols. Screening design was used to find the major variables within all possible process variables. Then, optimal conditions were studied using response surface.

The most appropriate condition was achieved using phosphatidylcholine of 4.5% (w/w), extract concentration of 0.7%, mixing time of 30 min and temperature of 50 °C. Encapsulation efficiency (EE) depended on concentrations of the green tea extract and phosphatidylcholine. The EE in optimal formulation was reached as 51.34%. The particle size and Z-potential of liposomal green tea extract were assessed at 419 nm and -59.7 mV, respectively. The total polyphenol content (TPC) of green tea included 164.2 mg gallic acid/g extract. Free radical scavenging activities of free and liposomal extracts were calculated as 90.6 and 93.37%, respectively, using 2-2-diphenyl-1-pycrylhydrazyl (DPPH) method.

Results revealed that liposomal green tea extract can be used extensively in food industries due to its high antioxidant activity. No size decreasing methods (e.g. sonication and homogenization) were needed to produce nanosize liposomal extracts to avoid structure instability.

Gamma-aminobutyric acid (GABA) is a non-protein four-carbon amino acid that has many physiological properties, including reducing blood pressure, accelerating protein synthesis in the brain, and treatment of insomnia and depression. This amino acid is produced by a number of lactic acid bacteria, fungi and yeasts. The objective of the present study was to identify probiotic bacteria with the maximum ability to generate GABA and optimize the bacterial culture conditions having the highest potential for GABA production.

The potential of GABA production by Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus rhamnosus, Lactobacillus casei, Streptococcus thermophilus, Lactobacillus brevis and Lactococcus lactis ssp. lactis in the culture medium of MRS broth was assessed by High Performance Liquid Chromatography (HPLC). In order to increase the rate of GABA produced by the bacteria having the highest potential for GABA production, the conditions of the culture medium including pH (3.5 to 6.5) "temperature (25 to 45°C), time (12 to 96 h) and glutamic acid (GA) concentration (25 to 650 mmol) were optimized by the Box-Behnken’s Response Surface Method (RSM).

Lactobacillus brevis had the highest potential of GABA production (5960.8 mg/l). The effect of time and GA concentration was significant on the amount of GABA production. The best conditions of culture medium to achieve the highest amount of GABA production by Lactobacillus brevis (19960 mg/l) were temperature 34.09°C, pH 4.65, GA concentration 650 mmol and time 96 h.

The results showed that by optimization of the culture medium conditions of probiotic bacteria we can produce more GABA in culture medium.

Tobacco etch virus (TEV) protease, a 27 KDa protein, consists of the catalytic domain of nuclear inclusion a (NIa) protein produced by Tobacco etch virus. Because of its unique sequence, TEV protease is used for purging fusion tags from proteins. It also has many advantages such as stability and activity in a board range of temperature and pH and overproduction in Escherichia coli and these benefits make this protease valuable. Despite all these benefits, TEV protease has problems like low solubility (less than 1 mg/mL). There are methods for enhancing protein solubility and in this study, the effect of additives during cell lysis was studied.

Eleven different additives that made twelve different lysis buffers were used and their effect on TEV protease solubility analyzed by Plackett-Burman and response surface methodology methods.

Three best effective additives on TEV solubility (L-proline, sodium selenite, and CuCl2) were selected according to software analysis and the best concentration of them was applied to optimize TEV protease solubility.

The obtained results provided the composition of an optimum solvent for obtaining soluble TEV protease.

L-Asparaginase (L-Asp) is used as an efficient anti-cancer drug, especially for acute lymphoblastic leukemia (ALL). Currently, two bacterial asparaginase isoenzymes are used for cancer treatment. Therefore, this research focused on isolating native bacteria with the ability to produce L-Asp. L-Asp producing bacteria were isolated from soil samples on 9K medium supplemented with L-Asp as nitrogen source. Detection of L-Asp activity was performed by observing color change of the agar medium from yellow to orange due to the release of ammonia around the colonies. After the isolation and identification of the bacterium, L-Asp production was first optimized by the one factor-at-the-time (OFAT) technique followed by the response surface method. Next, the enzyme was extracted, purified, and assessed for antileukemia activity on U937 and MRC-5 cell lines. The results revealed that L-Asp produced by Rouxiella sp. AF1 significantly inhibited the growth of U937 cells at a dose of up to 0.04 IU/ml, while MRC-5 was not affected at any enzyme doses. The final purification of the enzyme was achieved by column chromatography (Sephadex G-100) at approximately 0.31 mg/ml, and its specific activity was determined to be 0.51 IU/mg. The OFAT optimization experiments were performed primarily to determine optimal enzyme conditions, which were found to be neutral pH (pH7), 30 °C temperature, and 3 % NaCl, 1 % peptone, and 1% glucose concentrations. Statistical optimization   was based on five factors obtained from OFAT, and response surface method  (RSM) analysis introduced a quadratic model for enzyme production at the optimal range of these variables. This model provided an equation for measuring the effect of physiochemical conditions on final enzyme production. We showed that native bacteria may be novel candidates for isolating new metabolites such as L-Asp. Because many bacteria grow in unknown environments with unique ecological properties, the probability of discovering novel bacterial species producing bioactive compounds is high.

The objective of this study was to synthesize and statistically optimize dimethyl fumarate (DMF) loaded solid lipid nanoparticles (SLNs) for better management of multiple sclerosis (MS).
SLNs were formulated by hot emulsion, ultrasonication method and optimized with response surface methodology (RSM). A three factor and three level box-behnken design was used to demonstrate the role of polynomial quadratic equation and contour plots in predicting the effect of independent variables on dependent responses that were particle size and % entrapment efficiency (%EE).
The results were analyzed by analysis of variance (ANOVA) to evaluate the significant differences between the independent variables. The optimized SLNs were characterized and found to have an average particle size of 300 nm, zeta potential value of -34.89 mv and polydispersity index value This study showed that the present formulation with improved characteristics can be a promising formulation with a longer half-life for the better management of MS.

Solid lipid nanoparticles (SLNs) have been proven to possess pharmaceutical advantages. They have the ability to deliver hydrophilic drugs through lipid membranes of the body. However, the loading of such drugs into SLNs is challenging. Hydrophilic nicotinamide, a histone deacetylase inhibitor, is used to establish SLNs with enhanced encapsulation efficiency by using statistical design.
The possible effective parameters of these particles’ characteristics were determined using pre-formulation studies and preliminary tests. Afterwards, the Response Surface Method (RSM) was utilized to optimize the preparation condition of SLNs. The effect of the amount of lipid, drug, surfactant, and the mixing apparatus were studied on particle size, zeta potential, and encapsulation efficiency of the obtained particles. The acquired particles were characterized in respect of their morphology, in vitro release profile, and cytotoxicity.
According to this study, all the dependant variables could be fitted into quadratic models. Particles of 107 nm with zeta potential of about -40.9 and encapsulation efficiency of about 36% were obtained under optimized preparation conditions; i.e. with stearic acid to phospholipon® 90G ratio of 7.5 and nicotinamide to sodium taurocholate ratio of 14.74 using probe sonication. The validation test confirmed the model’s suitability. The release profile demonstrated the controlled release profile following the initial burst release. Neither the nicotinamide nor the SLNs showed toxicity under the evaluated concentrations.
The acquired results suggested the suitability of the model for designing the delivery system with a highly encapsulated water soluble drug for controlling its delivery.