Plackett-Burman Experimental Design Research Articles

Impact of process-induced variability on multi-bit phase change memory devices

Phase change memory (PCM) shows great potential for multi-bit data storage for the next-generation non-volatile, high-speed, high-density memories. However, the process-induced variability poses a serious threat to the performance of multi-bit switching in nano-scale PCM devices. In this study, the impact of structural and interfacial parameters are studied systematically on the multi-level RESET programming of mushroom-type Ge2Sb2Te5 (GST) PCM devices by using TCAD simulations. Here, the impact of unintentionally varying structural and interfacial input parameters is investigated for the optimized multi-bit PCM device of 60 nm heater diameter (HD) using the Plackett-Burman design of experiment. The quantitative analysis of input parameters shows that HD, GST thickness, and interfacial thermal resistance between GST and heater are the most sensitive parameters for the output parameter, RESET resistance (RRESET), while considering all the resistance levels from 1 to 7. Similarly, HD, heater height, and GST diameter are found to be the most governing parameters for RESET power (PRESET).

Production of high-value added exopolysaccharide by biotherapeutic potential Lactobacillus reuteri strain

Exopolysaccharides (EPS) are produced by various microbial groups including bacteria. EPS produced from Lactobacilli is gaining popularity as a new generation functional food to replace various chemically synthesized food additives. EPS production by strains of L. reuteri were reported previously in sourdough fermentation. The submerged cultivation of L. reuteri strain DSM 20016 T was optimised for crude EPS production. Initially, the factors controlling crude EPS generation were explored using one-at-a-time (OFAT). Among the investigated carbon sources, sucrose supplemented medium increased maximal crude EPS generation. Yeast extract was determined to be the greatest nitrogen source for increasing crude EPS and cell mass. Plackett-Burman experimental design (PBD) was employed to screen the important parameters impacting crude EPS production in the growing medium. Three important factors were identified: sucrose, yeast extract and sodium acetate. The RSM quadratic model for crude EPS generation was significant (R2:0.9373) and correlated with the observed response at roughly 94%. About 3.4 g L−1 crude EPS was produced under optimal fermentation conditions of sucrose (106.0 g L−1), yeast extract (30.0 g L−1) and sodium acetate (7.0 g L−1). This study shows the crude EPS synthesis of L. reuteri from sourdough can be used in submerged fermentation and biotechnological applications.

Tailoring the Optimized Fermentation Conditions of SCOBY-Based Membranes and Milk Kefir Grains to Promote Various Functional Properties.

Kombucha culture (named SCOBY-Symbiotic Culture of Bacteria and Yeasts) and milk kefir grains represent multiple consortia of wild microorganisms that include lactic acid bacteria, acetic acid bacteria and yeasts with valuable functional properties. Their fermentative potential provides a wide range of derivate metabiotics (prebiotics, probiotics, postbiotics and paraprobiotics) with valuable in vitro and in vivo benefits. This study targeted the evaluation of the functionality of a co-culture of SCOBY-based membranes and milk kefir grains, used as freeze-dried starter cultures, for the fermentation of a newly formulated medium based on black tea infusion, supplemented with bovine colostrum and sugar, in order to produce bioactive compounds with functional properties. The design and optimization of the biotechnological process were achieved by using the Plackett–Burman experimental design (six factorial points, three center points) and the response surface methodology and central composite design (three factorial points, six axial points and two center points in axial) tools. The statistical analysis and the mathematical modelling of the responses such as the pH, titratable acidity, antioxidant activity and antimicrobial activity (against Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Aspergillus niger) were investigated. Further, the composition of organic acids, polyphenols and flavonoids of the fermented product obtained under the optimized fermentation conditions was also analyzed. The fermentation of the medium containing 6.27% (w/v) bovine colostrum powder, 1.64% (w/v) black tea, 7.5% (w/w) sugar, pH 6.7, with an inoculum based of 0.36% (w/v) milk kefir grains powder and 0.5% (w/v) SCOBY-based membrane (both as freeze-dried culture), at 30 °C, for 5 days, in an aerobic stationary system, revealed an antifungal activity between 80 and 100% against Aspergillus niger, an antibacterial activity of 8–22 mm against Escherichia coli and Bacillus spp. And a titratable acidity of 445 °Th. The chemical composition of the obtained product had a positive impact on the functional properties of the fermented products in terms of the antimicrobial and antioxidant properties.

Application of Plackett-Burman and central composite design for analysis of Gadolinium in acetonitrile and TBAP supporting electrolyte by Differential Pulse Voltammetry

The voltammetry method offers fast, efficient and simple preparation for the detection of the sample containing rare earth elements (REE). The combination of voltammetry with the experimental design provided more efficient analysis especially the solvent consumption. This study aims to determine the factors that have an optimum effect using the experimental design results on the analysis of Gadolinium (Gd) in acetonitrile by Differential pulse voltammetry. The tertabuthylammonium perchlorate (TBAP) was used as supporting electrolyte. The screening and optimization of the parameter were carried out by Plackett-Burman experimental design and Central Composite Design. The two significant parameters were obtained for the analysis of Gd in acetonitrile by Differential pulse voltammetry (DPV) which are TBAP concentration value 0.1166 M and deposition potential at -0.7929 V.

Agro-waste as a substrate for the production of pullulanase by Penicillium viridicatum under solid-state fermentation

One of the key enzymes utilized in the food industry is pullulanase. But its major drawbacks are its low yield and high production costs. In this regard, the current research aims to screen agro-waste substrates for optimal pullulanase production in solid-state fermentation. Of various agro-wastes used as a substrate, the maximum enzymic activity (9.74 U/gds) was observed in a medium based on 5 g of green gram husk and incubated for 3 days at 30 °C. The effects of 16 different nutrients on the yield of pullulanase production were studied using the Plackett–Burman experimental design. The incorporation of FeSO4, MnSO4, and MgSO4 into the pullulanase production medium significantly increased the yield and showed a 5.7-fold increase (56.25 U/gds) in comparison with the unoptimized media. The Box-Behnken experimental design was used to study the effect of interactions between Fe2+, Mg2+, and Mn2+ on the production of pullulanase. Box-Behnken showed a 1.1-fold increase (62.1 U/gds) in pullulanase production. The total increase in yield after all optimization was 6.37-fold. The present study reports for the first time the applicability of green gram husk as a potent substrate for pullulanase production by Penicillium viridicatum.

Mixing and segregation assessment of bi-disperse solid particles in a double paddle mixer

A double paddle blender's flow patterns and mixing mechanisms were analyzed using discrete element method (DEM) and experiments. The mixing performance of this type of the blender containing bi-disperse particles has been rarely studied in the literature. Plackett-Burman design of experiments (DoE) methodology was used to calibrate the DEM input parameters. Subsequently, the impact of the particle number ratio, vessel fill level, and paddle rotational speed on mixing performance was investigated using the calibrated DEM model. The mixing performance was assessed using relative standard deviation and segregation intensity. Mixing performance was significantly affected by the paddle rotational speed and particle number ratio. Moreover, the Peclet number and diffusivity coefficient were used to evaluate the mixing mechanism in the blender. Results revealed that the diffusion was the predominant mixing mechanism, and the best mixing performance was observed when the diffusivity coefficients of 3 mm and 5 mm particles were almost equal.

Extracting Total Anthocyanin from Purple Sweet Potato Using an Effective Ultrasound-Assisted Compound Enzymatic Extraction Technology.

This study aimed to develop an effective technique for extracting total anthocyanins from purple sweet potato (Mianzishu 9) (PSP9) by ultrasound-assisted compound enzymatic extraction (UAEE). Single-factor experiments, Plackett-Burman experimental design, and response surface methodology were utilized for optimizing extraction conditions, and the antioxidant activities were evaluated. Anthocyanins were also measured using an ultra-performance liquid chromatograph linked to a mass spectrometer (UPLC-MS). The maximum yield of total anthocyanins was 2.27 mg/g under the following conditions: the ethanol concentration was 78%, the material-to-liquid ratio was 1:15 g/mL, the enzyme ratio (cellulase: pectinase: papain) was 2:2:1 and its hydrolysis was at 41 °C, pH = 4.5, 1.5 h, the ultrasonication was at 48 °C and conducted twice for 20 min each time. In addition to higher yield, anthocyanins extracted from purple sweet potato by UAEE showed great ability to scavenge DPPH (IC50 of 0.089 μg/mL) and hydroxyl radicals (IC50 of 100.229 μg/mL). Five anthocyanins were found in the purple sweet potato extract from UAEE. Taken together, the ultrasound-assisted compound enzymatic method can rapidly and effectively extract anthocyanins with greater antioxidant capacity from purple sweet potato.

Formulation-by-Design of Efinaconazole Spanlastic Nanovesicles for Transungual Delivery Using Statistical Risk Management and Multivariate Analytical Techniques.

As regulatory and technical landscapes for pharmaceutical formulation development are rapidly evolving, a risk-management approach using multivariate analysis is highly essential for designing a product with requisite critical quality attributes (CQA). Efinaconazole, a newly approved poorly water-soluble antifungal triazole drug has poor permeability. Spanlastics, new-generation surfactant nanovesicles, being fluidic, help improve the permeability of drugs. Therefore, we optimized efinaconazole spanlastics using the concepts of Formulation-by-Design (FbD) and explored the feasibility of transungual delivery for the management of onychomycosis. Using the Ishikawa fishbone diagram, the risk factors that may have an impact on the CQA of efinaconazole spanlastic vesicles were identified. Application of the Plackett–Burman experimental design facilitated the screening of eight different formulation and process parameters influencing particle size, transmittance, relative deformability, zeta potential, entrapment efficiency, and dissolution efficiency. With the help of Pareto charts, the three most significant factors were identified, viz., vesicle builder (Span), edge activator (Tween), and mixing time. The levels of these three critical variables were optimized by FbD to reduce the particle size and maximize the transparency, relative deformability, encapsulation efficiency, and dissolution efficiency of efinaconazole spanlastic nanovesicles. Bayesian and Lenth’s analysis and mathematical modeling of the experimental data helped to quantify the critical formulation attributes required for getting the formulation with optimum quality features. The optimized efinaconazole-loaded spanlastic vesicles had a particle size of 197 nm, transparency of 91%, relative deformability of 12.5 min, and dissolution efficiency of 81.23%. The spanlastic formulation was incorporated into a gel and explored ex vivo for transungual delivery. This explorative study provides an example of the application of principles of risk management, statistical multivariate analysis, and the FbD approach in developing efinaconazole spanlastic nanovesicles.

Application of Plackett-Burman Experimental Design for Investigating the Effect of Eight Phytohormones on Malt Quality Parameters

Barley is the major raw material for the malting and brewing industries. Seed germination is a fundamental process for malting and is affected by physical and chemical factors, especially plant hormones. It is well recognized that the phytohormones gibberellic acid (GA) and abscisic acid (ABA) are the primary hormones that antagonistically regulate barley germination. Other plant hormones, including auxin (IAA), ethylene (ET), brassinosteroid (BR), jasmonic acid (JA), salicylic acid (SA), cytokinins (CTKs), and strigolactone (SLs) also regulate seed germination by mediating the ABA/GA balance. In this study, the effects of eight hormones added during barley germination were investigated. An efficient design of the experimental method was employed to assess the effect of eight factors (α-amylase, β-amylase, limit dextrinase, β-glucanase, wort sugar profile, FAN, and β-glucan content) on epicotyl and root elongation. Almost all studied phytohormones played a significant role on barley epicotyl elongation. GA, ET, BA (benzylaminopurine), and zeatin (ZEA) exerted an increased effect, while ABA, SA, and BR showed a decreased effect for α-amylase, β-amylase, limit dextrinase, and β-glucanase activity. Results showed that in addition to GA and ABA, that SA, ET, BR, BA, ZEA, and JA also had significant effects on malt quality. The balance between these phytohormones is vital to the malting quality of barley. Future applications of these results could improve current recognition about the effects of phytohormones on malting and provide concrete ideas for enhancing malt quality.

Optimising production of a biochar made from conifer brash and investigation of its potential for phosphate and ammonia removal

As a lignocellulose biomass, waste conifer brash (waste treetops and branches) from felled afforested peatland sites can be converted to biochar through pyrolysis, thus creating a potentially useful product. Here, we propose that brash from ‘forest-to-bog’ peatland restoration sites through conversion to biochar, could be utilised for nutrient (PO43−-P and NH4+-N) removal at such restoration sites, or within the water sector. As a first step, we explore the factors involved in biochar production that will result in high nutrient adsorption efficiency and pyrolysis yield and low production cost (using a Plackett-Burman experimental design (PBD)). Central composite design (CCD) was used for further optimisation of pyrolysis time and temperature as the two most significant factors. Model predictions for an optimised biochar (OB) suggested pyrolysis conditions of 500 °C for 30 min could achieve the highest yield of 34.75 %, the lowest cost of 0.37 £ /kg, and the highest PO43−-P and NH4+-N removal of 9.9 % and 65.2 %, respectively. Additionally, the OB morphology, structure and surface chemistry were characterised using different instrumental techniques which showed typical features for a wood-based biochar. While the OB did remove NH4+-N from solution (due to the presence of negatively charged functional groups), it did not remove significant amounts of PO43--P, indeed it leached PO43--P back into solution. Therefore, an unmodified biochar produced from conifer brash did not fulfil the aim of removing these two key nutrient pollutants for use in improving water quality at restoration sites. To address this challenge, the surface chemistry of the OB could be functionalised to increase its affinity toward both PO43−-P and NH4+-N ions.

A novel experimental design for boar sperm cryopreservation.

Cryopreservation of sperm is a routine technology in many livestock species, but not in swine. Frozen sperm must result in acceptable conception rates and produce 11 to 12 piglets/litter to be competitive with traditional cooled semen. The development of an extender that results in high post-thaw sperm quality and acceptable litter size requires the identification of factors that markedly affect post-thaw semen quality. The present study aims to first identify factors in boar sperm cryopreservation that significantly affect post-thaw sperm quality using an efficient, cost-effective, and relatively rapid approach. The Plackett-Burman experimental design is ideal for the screening of factors at their extreme, greatly reducing the amount of time and resources needed for a follow-up, full factorial design. Using commercial semen, a 9-factor, 12-run Plackett-Burman design was used on 10 boars split between 12 treatments. Through this method, glycerol concentration, cooling rate, antioxidant supplementation with GameteGuard (Membrane Protective Technologies, Inc. Fort Collins, CO), and straw size were identified as highly influential factors that affect post-thaw sperm quality. Extender type, starting osmolality, sodium dodecyl sulfate addition, and stepwise addition of glycerol were also influential for some but not all post-thaw sperm parameters (P < 0.05). Equilibration time in the straws before freezing was determined to have no impact on post-thaw sperm quality parameters. Using the Plackett-Burman design, it can be concluded that four of the nine factors warrant detailed investigation in full factorial experiments in the development of boar sperm cryopreservation extenders.

Investigation of the optimum conditions for electricity generation by haloalkaliphilic archaeon Natrialba sp. GHMN55 using the Plackett–Burman design: single and stacked MFCs

The production of bioelectricity via the anaerobic oxidation of organic matter by microorganisms is recently receiving much interest and is considered one of the future alternative technologies. In this study, we aimed to produce electrical current by using facultative halophilic archaeon Natrialba sp. GHMN55 as a biocatalyst at the anode of a microbial fuel cell (MFC) to generate electrons from the anaerobic breakdown of organic matter to produce electrical current. Since the MFC’s performance can be affected by many factors, the Plackett–Burman experimental design was applied to optimize the interaction between these factors when tested together and to identify the most significant factors that influence bioelectricity generation. We found that the factors that significantly affected electrical current generation were casein, inoculum age, magnet-bounded electrodes, NaCl, resistor value, and inoculum size; however, the existence of a mediator and the pH showed negative effects on bioelectricity production, where the maximum value of the 200 mV voltage was achieved after 48 h. The optimum medium formulation obtained using this design led to a decrease in the time required to produce bioelectricity from 20 days (in the basal medium) to 2 days (in the optimized medium). Also, the overall behavior of the cell could be enhanced by using multiple stacked MFCs with different electrical configurations (such as series or parallel chambers) to obtain higher voltages or power densities than the single chambers where the series chambers were recorded at 27.5 mV after 48 h of incubation compared with 12.6 mV and 1.1 mV for parallel and single chambers, respectively. These results indicate that the order of preferred MFC designs regarding total power densities would be series > parallel > single.

Best-performing Bacillus strains for microbiologically induced CaCO3 precipitation: Screening of relative influence of operational and environmental factors

The microbiologically induced calcite precipitation (MICP) can be an emerging approach that could tap onto soil bacterial diversity and use as a bioremediation technique. Based on the concept that bacteria with biomineralization capacity could be effective CaCO3 inductance agents, this study aimed to evaluate the simultaneous influence of 11 operational and environmental factors on the MICP process, for the first time. Therefore, Bacillus muralis, B. lentus, B. simplex, B. firmus, and B. licheniformis, isolated from alkaline soils, were used in the selection of the best performing bacterium compared with a well-known MICP bioagent Sporosarcina pasteurii DSM 33. Plackett-Burman's experimental design was labouring to screen all independent variables for their significances on five outputs (pH value, number of viable cells and spores, amount of urea and CaCO3 precipitate). According to experimentally obtained data, an artificial neural network model based on the Broyden-Fletcher-Goldfarb-Shanno algorithm showed good prediction capabilities, while differences in the relative influences were observed at the bacterial strain level. B. licheniformis turn out to be the most potent bioagent, with a maximum amount of CaCO3 precipitate of 3.14 g/100 mL in the optimal conditions.

Assessment of the principal factors influencing the silver cyanidation process by using Plackett-Burman experimental design

For decades, the cyanidation process is frequently used for gold and silver extraction, as well as metal extraction as a sub-product of lead, zinc, and copper metallurgy. The present study focuses on the factors that influence silver extraction efficiency, which represents the rate of silver dissolution in a sodium cyanide solution. The screening design of Plackett and Burman has been performed to investigate the variables that have the most impact on the extraction of metal namely temperature, pH, free cyanide concentration, dissolved oxygen level, pulp density, lead nitrate ratio (Pb(NO3)2ratio), and setting time.To evaluate the meaning of the seven variables, twelve experiments were carried out and the result revealed that for a 95% confidence level, the chosen parameters for the model are meaningful in their whole. The following three factors were significant (P<0.05) when it comes to the silver cyanidation process including, setting time, pulp density, and free cyanide concentration. The variance analysis (ANOVA) using a Fisher test has shown that the setting time was considered to have the most significant effect for a significance level of 1% (Fstatistics=22.8328 > Fc=21.2). Likewise, for a 95% confidence level, both pulp density and free cyanide concentration have a major influence on the response. The Pareto diagram results clearly show that pulp density and setting time represent 20% of factors that have 80% effect on the silver extraction. Model validation verified that no statistically relevant distinction was made between the predicted and experimental results with the determination coefficient R2=0.93, this mean that the metal extraction is better fitted to the model and the predictability of the model is adequate to explain 93% of the variation in the dependent variable as a function of factor variation.

Optimization of process technology and quality analysis of a new yogurt fortified with Morchella esculenta

To optimize the process technology of yogurt fortified with M. esculenta, first, the Plackett-Burman experimental design combined with the central composite design (CCD) were used to investigate the effects of four parameters on the sensory score. Then, artificial neural networks (ANN) and genetic algorithm (GA) were used to evaluate the process parameters of the fortified yogurt. Finally, the quality of the yogurt prepared under optimal conditions were observed. The results showed that the optimal parameters from ANN-GA were: 0.2 g of mycelia, 15 g milk powder, 6.4 g sucrose, and a fermentation temperature of 38 °C, with the highest predicted sensory score of 97.1 points, which was more accurate and reliable than CCD. Mycelia of M. esculenta gave the yogurt excellent quality, including good acidity (95 ± 2.85° T) and water holding capacity (64.32 ± 4.25%) after 21 days storage at 4 °C; firmness (12.98 ± 1.25) g, consistency (22.85 ± 0.92) g·sec, stickness (-6.16 ± 0.38) g, stringiness (3.53 ± 0.12) mm, and cohesion index (-6.62 ± 1.75) g·sec. Moreover, the living lactic acid bacteria of the yogurt with M. esculenta (6.23 ± 0.23) × 107 CFU/mL) were significantly higher than that of the control yogurt (5.65 ± 0.31) × 107 CFU/mL. This could provide a theoretical basis and parameter guidance for developing a new functional yogurt.

Characterization and statistical optimization of γ-PGA produced by Bacillus megaterium UP47 isolated from Pentaclethra macrophylla.

Gamma-polyglutamic acid (γ-PGA) is a microbially produced non-toxic peptide biopolymer which is gaining grounds in many biotechnological fields and has a wide range of applications. In this study, the characteristics of γ-PGA produced by Bacillus megaterium isolated from an oil seed were determined, while the nutritional requirements of the bacterium were optimized using a predictive 15 factor-16 run Plackett-Burman experimental design. The main effect of each factor, the interaction and quadratic effects of the factors on optimized production were determined from Box-Benkhen model using Dell Statistica v. 12 and 13 software. Bacillus megaterium UP47 produced the highest γ-PGA (16.33 g/L) out of 56 spore-forming Bacillus strains isolated from soil, water and fermented food samples. Hydrolysates of the produced γ-PGA had a retention factor which corresponded to the L-glutamic acid standard (retention factor (rf) 0.35), while high-definition fourier transform infrared (FT-IR) spectroscopic imaging showed characteristic peaks representative of the active bonds present in γ-PGA. The γ-PGA at a concentration as low as 50 mg/100 mL exerted antimicrobial inhibitions against test pathogens. A 2.00 w/v γ-PGA solution had 11 mm and 13 mm inhibition zones against Staphylococcus aureus and Shigella dysenteriae, respectively. A second order polynomial equation for prediction of γ-PGA was derived as: γPGA yield = 3316.061 - 449.708A + 9.036A2 - 139.813B + 3.095B2 - 7.699C - 0.164C2 + 13.116AB - 0.087AB2 - 0.248A2B + 3.781AC - 0.076A2C - 0.394BC. It showed an increase in γ-PGA yield with increasing L-glutamic acid and biotin, but a decrease with yeast extract. Bacillus megaterium UP47 had a maximum γ-PGA yield of 54 g/L and 62 g/L, respectively, from the Plackett-Burman and Box-Benkhen design, thereby resulting in an appreciable increase in polymer yield after the optimization process with a 95% confidence level.

Effects of Inhibitory Compounds Present in Lignocellulosic Biomass Hydrolysates on the Growth of Bacillus subtilis

This study evaluated the individual and combined effects of inhibitory compounds formed during pretreatment of lignocellulosic biomass on the growth of Bacillus subtilis. Ten inhibitory compounds commonly present in lignocellulosic hydrolysates were evaluated, which included sugar degradation products (furfural and 5-hydroxymethylfurfural), acetic acid, and seven phenolic compounds derived from lignin (benzoic acid, vanillin, vanillic acid, ferulic acid, p-coumaric acid, 4-hydroxybenzoic acid, and syringaldehyde). For the individual inhibitors, syringaldehyde showed the most toxic effect, completely inhibiting the strain growth at 0.1 g/L. In the sequence, assays using mixtures of the inhibitory compounds at a concentration of 12.5% of their IC50 value were performed to evaluate the combined effect of the inhibitors on the strain growth. These experiments were planned according to a Plackett–Burman experimental design. Statistical analysis of the results revealed that in a mixture, benzoic acid and furfural were the most potent inhibitors affecting the growth of B. subtilis. These results contribute to a better understanding of the individual and combined effects of inhibitory compounds present in biomass hydrolysates on the microbial performance of B. subtilis. Such knowledge is important to advance the development of sustainable biomanufacturing processes using this strain cultivated in complex media produced from lignocellulosic biomass, supporting the development of efficient bio-based processes using B. subtilis.

Statistical modeling and optimization for the production of secondary metabolites by lichen mycobiont isolated from Parmotrema austrosinense

Lichens produce range of secondary metabolites which exhibit multifarious biological potential. The present work highlights the effect of media components for the production of secondary metabolites by lichen Parmotrema austrosinense. Mycobiont was isolated by lichen tissue culture method. One variable at a time approach exhibited that, Malt yeast extract media supplemented with glucose (4 mg/L), asparagine (1 mg/L), MnSO4 4H2O (20 mg/L), ZnSO4 7H2O (20 mg/L) and H3BO3 (4 mg/L) enhanced the growth of lichen mycobiont with improved total phenol production. The major influencing media components on total phenol content was screened through Plackett-Burman experimental design. Yeast, glucose and MgSO4 4H2O have been observed as effective media components. The screened variables have been further optimized by response surface methodology. The optimum media composition was found as 4.04 g/L glucose, 3.15 g/L yeast and 21.43 mg/L MnSO4 4H2O resulted with the maximum total phenol content of 1.80 ± 0.1 μg/g. Thus, the study established a suitable media component for the enhanced production rate of secondary metabolites in terms of total phenol content.

Multiparameter optimization of magnetite solid-phase microextraction for preconcentration of diclofenac and determination by UV–Vis Spectrophotometry

In this work, a clean and simple magnetic solid-phase microextraction based on L-arginine modified magnetic dialdehyde starch nanocomposite was developed for the preconcentration and determination of diclofenac in biological samples by UV–Vis Spectrophotometry. A Plackett–Burman experimental design was used to evaluate the influence of effective parameters. Significant parameters were further optimized by Central Composite Design. Sample volume, pH and salting effect had a main effect on extraction of diclofenac by the proposed method. Under the optimized conditions, the detection limit (3 \({S}_{b}\), n = 7) was found to be 0.039 µg ml−1. The calibration curve showed dynamic linear 0.05–10 µg ml−1 with correlation coefficients (R2) of 0.987. The enrichment factor was found to be 148. The proposed method showed good results for preconcentration and determination of diclofenac in serum and pharmaceutical samples.

Carbon nanomaterial properties help to enhance xylanase production from recombinant Kluyveromyces lactis through a cell immobilization method.

Carbon nanomaterials, due to their catalytic activity and high surface area, have potential as cell immobilization supports to increase the production of xylanase. Recombinant Kluyveromyces lactis used for xylanase production was integrated into a polymeric gel network with carbon nanomaterials. Carbon nanomaterials were pretreated before cell immobilization with hydrochloric acid (HCl) treatment and glutaraldehyde (GA) crosslinking, which contributes to cell immobilization performance. Carbon nanotubes (CNTs) and graphene oxide (GO) were further screened using a Plackett-Burman experimental design. Cell loading and agar concentration were the most important factors in xylanase production with low cell leakage. Under optimized conditions, xylanase production was increased by more than 400% compared to free cells. Immobilized cell material containing such high cell densities may exhibit new and unexplored beneficial properties because the cells comprise a large fraction of the component. The use of carbon nanomaterials as a cell immobilization support along with the entrapment method successfully enhances the production of xylanase, providing a new route to improved bioprocessing, particularly for the production of enzymes. KEY POINTS: • Carbon nanomaterials (CNTs, GO) have potential as cell immobilization supports. • Entrapment in a polymeric gel network provides space for xylanase production. • Plackett-Burman design screen for the most important factor for cell immobilization.