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Fulltext Purification and Characterization of Lipase Produced by Leuconostoc mesenteroides Subsp. mesenteroides ATCC 8293 Using an Aqueous Two-Phase System (ATPS) Composed of Triton X-100 and Maltitol

Eko Sukohidayat NH, Zarei M, Baharin BS, Manap MY

Molecules, 2018 Jul 20;23(7).
PMID: 30037038 DOI: 10.3390/molecules23071800

Purification of lipase produced by L. mesenteroides subsp. mesenteroides ATCC 8293 was conducted for the first time using a novel aqueous two-phase system (ATPS) composed of Triton X-100 and maltitol. The partitioning of lipase was optimized according to several parameters including pH, temperature, and crude load. Results showed that lipase preferentially migrated to the Triton X-100 rich phase and optimum lipase partitioning was achieved in ATPS at TLL of 46.4% and crude load of 20% at 30 °C and pH 8, resulting in high lipase purification factor of 17.28 and yield of 94.7%. The purified lipase showed a prominent band on SDS-PAGE with an estimated molecular weight of 50 kDa. The lipase was stable at the temperature range of 30⁻60 °C and pH range of 6⁻11, however, it revealed its optimum activity at the temperature of 37 °C and pH 8. Moreover, lipase exhibited enhanced activity in the presence of non-ionic surfactants with increased activity up to 40%. Furthermore, results exhibited that metals ions such as Na⁺, Mg2+, K⁺ and Ca2+ stimulated lipase activity. This study demonstrated that this novel system could be potentially used as an alternative to traditional ATPS for the purification and recovery of enzymes since the purified lipase still possesses good process characteristics after undergoing the purification process.

Matched MeSH terms: Surface-Active Agents/chemistry
Purification and characterisation of an F16L mutant of a thermostable lipase

Ali MS, Yun CC, Chor AL, Rahman RN, Basri M, Salleh AB

Protein J, 2012 Mar;31(3):229-37.
PMID: 22350313 DOI: 10.1007/s10930-012-9395-8

A mutant of the lipase from Geobacillus sp. strain T1 with a phenylalanine to leucine substitution at position 16 was overexpressed in Escherichia coli strain BL21(De3)pLysS. The crude enzyme was purified by two-step affinity chromatography with a final recovery and specific activity of 47.4 and 6,315.8 U/mg, respectively. The molecular weight of the purified F16L lipase was approximately 43 kDa by 12% SDS-PAGE analysis. The F16L lipase was demonstrated to be a thermophilic enzyme due its optimum temperature at 70 °C and showed stability over a temperature range of 40-60 °C. The enzyme exhibited an optimum pH 7 in phosphate buffer and was relatively stable at an alkaline pH 8-9. Metal ions such as Ca(2+), Mn(2+), Na(+), and K(+) enhanced the lipase activity, but Mg(2+), Zn(2+), and Fe(2+) inhibited the lipase. All surfactants tested, including Tween 20, 40, 60, 80, Triton X-100, and SDS, significantly inhibited the lipolytic action of the lipase. A high hydrolytic rate was observed on long-chain natural oils and triglycerides, with a notable preference for olive oil (C18:1; natural oil) and triolein (C18:1; triglyceride). The F16L lipase was deduced to be a metalloenzyme because it was strongly inhibited by 5 mM EDTA. Moderate inhibition was observed in the presence of PMSF at a similar concentration, indicating that serine residues are involved in its catalytic action. Further, the activity was not impaired by water-miscible solvents, including methanol, ethanol, and acetone.

Matched MeSH terms: Surface-Active Agents/chemistry
Recent Developments of Reverse Micellar Techniques for Lysozyme, Bovine Serum Albumin, and Bromelain Extraction

Chia SR, Tang MSY, Chow YH, Ooi CW, Rambabu K, Zhu L, et al.

Mol Biotechnol, 2019 Oct;61(10):715-724.
PMID: 31350687 DOI: 10.1007/s12033-019-00200-7

Biomolecules produced by living organisms can perform vast array of functions and play an important role in the cell. Important biomolecules such as lysozyme, bovine serum albumin (BSA), and bromelain are often studied by researchers due to their beneficial properties. The application of reverse micelles is an effective tool for protein separation from their sources due to the special system structure. Mechanisms of transferring biomolecules and factors that influence the extraction of biomolecules are reviewed in this paper. The enhancement of biomolecule extraction could be achieved depending on the properties of reverse micelles. This paper provides an overall review on lysozyme, BSA, and bromelain extraction by reverse micelle for various applications.

Matched MeSH terms: Surface-Active Agents/chemistry
Recent developments in improving the emulsifying properties of chitosan

Yang Y, Gupta VK, Amiri H, Pan J, Aghbashlo M, Tabatabaei M, et al.

Int J Biol Macromol, 2023 Jun 01;239:124210.
PMID: 37001778 DOI: 10.1016/j.ijbiomac.2023.124210

Chitosan is one of the valuable products obtained from crustacean waste. The unique characteristics of chitosan (antimicrobial, antioxidant, anticancer, and anti-inflammatory) have increased its application in various sectors. Besides unique biological properties, chitosan or chitosan-based compounds can stabilize emulsions. Nevertheless, studies have shown that chitosan cannot be used as an efficient stabilizer because of its high hydrophilicity. Hence, this review aims to provide an overview of recent studies dealing with improving the emulsifying properties of chitosan. In general, two different approaches have been reported to improve the emulsifying properties of chitosan. The first approach tries to improve the stabilization property of chitosan by modifying its structure. The second one uses compounds such as polysaccharides, proteins, surfactants, essential oils, and polyphenols with more wettability and emulsifying properties than chitosan's particles in combination with chitosan to create complex particles. The tendency to use chitosan-based particles to stabilize Pickering emulsions has recently increased. For this reason, more studies have been conducted in recent years to improve the stabilizing properties of chitosan-based particles, especially using the electrostatic interaction method. In the electrostatic interaction method, numerous research has been conducted on using proteins and polysaccharides to increase the stabilizing property of chitosan.

Matched MeSH terms: Surface-Active Agents/chemistry
Recovery of synthetic dye from simulated wastewater using emulsion liquid membrane process containing tri-dodecyl amine as a mobile carrier

Othman N, Zailani SN, Mili N

J Hazard Mater, 2011 Dec 30;198:103-12.
PMID: 22023906 DOI: 10.1016/j.jhazmat.2011.10.014

The extraction of Red 3BS reactive dye from aqueous solution was studied using emulsion liquid membrane (ELM). ELM is one of the processes that have very high potential in treating industrial wastewater consisting of dyes. In this research, Red 3BS reactive dye was extracted from simulated wastewater using tridodecylamine (TDA) as the carrier agent, salicyclic acid (SA) to protonate TDA, sodium chloride as the stripping agent, kerosene as the diluent and SPAN 80 as emulsifier. Experimental parameters investigated were salicyclic acid concentration, extraction time, SPAN 80 concentration, sodium chloride concentration, TDA concentration, agitation speed, homogenizer speed, emulsifying time and treat ratio. The results show almost 100% of Red 3BS was removed and stripped in the receiving phase at the optimum condition in this ELM system. High voltage coalesce was applied to break the emulsion hence, enables recovery of Red 3BS in the receiving phase.

Matched MeSH terms: Surface-Active Agents/chemistry
Renewable resources-based approach to biantennary glycolipids

Tabandeh M, Salman AA, Goh EW, Heidelberg T, Hussen RSD

Chem Phys Lipids, 2018 05;212:111-119.
PMID: 29409839 DOI: 10.1016/j.chemphyslip.2018.01.011

A new synthesis approach towards biantennary lipids of Guerbet glycoside type was developed based on oleic acid as sustainable resource. Functionalization of the double bond provided access to primary alcohols with α-branched C19-skeleton. Formulation studies with corresponding lactosides indicated formation of vesicles with high assembly stability. A relatively narrow bimodal size distribution of the latter, which turns into a narrow unimodal distribution of small vesicles upon addition of an ionic cosurfactant, suggests potential for a vesicular drug delivery system.

Matched MeSH terms: Surface-Active Agents/chemistry
Fulltext Reverse micelle Extraction of Antibiotics using an Eco-friendly Sophorolipids Biosurfactant

Chuo SC, Abd-Talib N, Mohd-Setapar SH, Hassan H, Nasir HM, Ahmad A, et al.

Sci Rep, 2018 01 11;8(1):477.
PMID: 29323139 DOI: 10.1038/s41598-017-18279-w

Reverse micelles extraction of erythromycin and amoxicillin were carried out using the novel Sophorolipids biosurfactant. By replacing commonly used chemical surfactants with biosurfactant, reverse micelle extraction can be further improved in terms of environmental friendliness and sustainability. A central composite experimental design was used to investigate the effects of solution pH, KCl concentration, and sophorolipids concentration on the reverse micelle extraction of antibiotics. The most significant factor identified during the reverse micelle extraction of both antibiotics is the pH of aqueous solutions. Best forward extraction performance for erythromycin was found at feed phase pH of approximately 8.0 with low KCl and sophorolipids concentrations. Optimum recovery of erythromycin was obtained at stripping phase pH around 10.0 and with low KCl concentration. On the other hand, best forward extraction performance for amoxicillin was found at feed phase pH around 3.5 with low KCl concentration and high sophorolipids concentration. Optimum recovery of erythromycin was obtained at stripping phase pH around 6.0 with low KCl concentration. Both erythromycin and amoxicillin were found to be very sensitive toaqueous phase pH and can be easily degraded outside of their stable pH ranges.

Matched MeSH terms: Surface-Active Agents/chemistry*
Fulltext Rheology Impact of Various Hydrophilic-Hydrophobic Balance (HLB) Index Non-Ionic Surfactants on Cyclopentane Hydrates

Foo KS, Bavoh CB, Lal B, Mohd Shariff A

Molecules, 2020 Aug 15;25(16).
PMID: 32824121 DOI: 10.3390/molecules25163725

In this study, series of non-ionic surfactants from Span and Tween are evaluated for their ability to affect the viscosity profile of cyclopentane hydrate slurry. The surfactants; Span 20, Span 40, Span 80, Tween 20, Tween 40 and Tween 80 were selected and tested to provide different hydrophilic-hydrophobic balance values and allow evaluation their solubility impact on hydrate formation and growth time. The study was performed by using a HAAKE ViscotesterTM 500 at 2 °C and a surfactant concentration ranging from 0.1 wt%-1 wt%. The solubility characteristic of the non-ionic surfactants changed the hydrate slurry in different ways with surfactants type and varying concentration. The rheological measurement suggested that oil-soluble Span surfactants was generally inhibitive to hydrate formation by extending the hydrate induction time. However, an opposite effect was observed for the Tween surfactants. On the other hand, both Span and Tween demonstrated promoting effect to accelerate hydrate growth time of cyclopentane hydrate formation. The average hydrate crystallization growth time of the blank sample was reduced by 86% and 68% by Tween and Span surfactants at 1 wt%, respectively. The findings in this study are useful to understand the rheological behavior of surfactants in hydrate slurry.

Matched MeSH terms: Surface-Active Agents/chemistry*
Role of extremophilic Bacillus cereus KH1 and its lipopeptide in treatment of organic pollutant in wastewater

Nor FHM, Abdullah S, Ibrahim Z, Nor MHM, Osman MI, Al Farraj DA, et al.

Bioprocess Biosyst Eng, 2023 Mar;46(3):381-391.
PMID: 35779113 DOI: 10.1007/s00449-022-02749-1

An effective biosurfactant producer and extremophiles bacteria, Bacillus cereus KH1, was isolated from textile effluent and the biosurfactant was produced using molasses as the sole carbon source. Growth parameters such as pH, temperature, salinity and concentration of molasses were optimised for decolourising the textile effluent with 24-h incubation. The biosurfactant property of B. cereus KH1 was evaluated based on haemolytic activity, oil displacement technique, drop-collapsing test and emulsification index. The results of the produced biosurfactant showed a positive reaction in haemolytic activity, oil displacement technique, drop-collapsing test and exhibiting a 67% emulsification index. The cell-free broth was stable in 40 °C pH 7, 7% salinity and 7% molasses. Thin-Layer Chromatography and Fourier Transform Infrared Spectroscopy analysis revealed that the biosurfactant was a lipopeptide with a yield 2.98 g L-1. These findings proved the synergistic action of B. cereus KH1 with lipopeptide biosurfactant may accelerated the decolourisation efficiency to 87%.

Matched MeSH terms: Surface-Active Agents/chemistry
Role of genetic algorithms and artificial neural networks in predicting the phase behavior of colloidal delivery systems

Agatonovic-Kustrin S, Alany RG

Pharm Res, 2001 Jul;18(7):1049-55.
PMID: 11496944

PURPOSE: A genetic neural network (GNN) model was developed to predict the phase behavior of microemulsion (ME), lamellar liquid crystal (LC), and coarse emulsion forming systems (W/O EM and O/W EM) depending on the content of separate components in the system and cosurfactant nature.
METHOD: Eight pseudoternary phase triangles, containing ethyl oleate as the oil component and a mixture of two nonionic surfactants and n-alcohol or 1,2-alkanediol as a cosurfactant, were constructed and used for training, testing, and validation purposes. A total of 21 molecular descriptors were calculated for each cosurfactant. A genetic algorithm was used to select important molecular descriptors, and a supervised artificial neural network with two hidden layers was used to correlate selected descriptors and the weight ratio of components in the system with the observed phase behavior.
RESULTS: The results proved the dominant role of the chemical composition, hydrophile-lipophile balance, length of hydrocarbon chain, molecular volume, and hydrocarbon volume of cosurfactant. The best GNN model, with 14 inputs and two hidden layers with 14 and 9 neurons, predicted the phase behavior for a new set of cosurfactants with 82.2% accuracy for ME, 87.5% for LC, 83.3% for the O/W EM, and 91.5% for the W/O EM region.
CONCLUSIONS: This type of methodology can be applied in the evaluation of the cosurfactants for pharmaceutical formulations to minimize experimental effort.

Matched MeSH terms: Surface-Active Agents/chemistry
Screening biosurfactant-producing actinomycetes: Identification of Streptomyces sp. RP1 as a potent species for bioremediation

Ayoib A, Gopinath SCB, Zambry NS, Yahya ARM

J Basic Microbiol, 2024 Apr;64(4):e2300585.
PMID: 38346247 DOI: 10.1002/jobm.202300585

This study aimed to isolate biosurfactant-producing and hydrocarbon-degrading actinomycetes from different soils using glycerol-asparagine and starch-casein media with an antifungal agent. The glycerol-asparagine agar exhibited the highest number of actinomycetes, with a white, low-opacity medium supporting pigment production and high growth. Biosurfactant analyses, such as drop collapse, oil displacement, emulsification, tributyrin agar test, and surface tension measurement, were conducted. Out of 25 positive isolates, seven could utilize both olive oil and black oil for biosurfactant production, and only isolate RP1 could produce biosurfactant when grown in constrained conditions with black oil as the sole carbon source and inducer, demonstrating in situ bioremediation potential. Isolate RP1 from oil-spilled garden soil is Gram-staining-positive with a distinct earthy odor, melanin formation, and white filamentous colonies. It has a molecular size of ~621 bp and 100% sequence similarity to many Streptomyces spp. Morphological, biochemical, and 16 S rRNA analysis confirmed it as Streptomyces sp. RP1, showing positive results in all screenings, including high emulsification activity against kerosene (27.2%) and engine oil (95.8%), oil displacement efficiency against crude oil (7.45 cm), and a significant reduction in surface tension (56.7 dynes/cm). Streptomyces sp. RP1 can utilize citrate as a carbon source, tolerate sodium chloride, resist lysozyme, degrade petroleum hydrocarbons, and produce biosurfactant at 37°C in a 15 mL medium culture, indicating great potential for bioremediation and various downstream industrial applications with optimization.

Matched MeSH terms: Surface-Active Agents/chemistry
Fulltext Seeded Growth Route to Noble Calcium Carbonate Nanocrystal

Islam A, Teo SH, Rahman MA, Taufiq-Yap YH

PLoS One, 2015;10(12):e0144805.
PMID: 26700479 DOI: 10.1371/journal.pone.0144805

A solution-phase route has been considered as the most promising route to synthesize noble nanostructures. A majority of their synthesis approaches of calcium carbonate (CaCO3) are based on either using fungi or the CO2 bubbling methods. Here, we approached the preparation of nano-precipitated calcium carbonate single crystal from salmacis sphaeroides in the presence of zwitterionic or cationic biosurfactants without external source of CO2. The calcium carbonate crystals were rhombohedron structure and regularly shaped with side dimension ranging from 33-41 nm. The high degree of morphological control of CaCO3 nanocrystals suggested that surfactants are capable of strongly interacting with the CaCO3 surface and control the nucleation and growth direction of calcium carbonate nanocrystals. Finally, the mechanism of formation of nanocrystals in light of proposed routes was also discussed.

Matched MeSH terms: Surface-Active Agents/chemistry*
Semi-empirical spectrophotometric (SESp) method for the indirect determination of the ratio of cationic micellar binding constants of counterions X⁻ and Br⁻(K(X)/K(Br))

Khan MN, Yusof NS, Razak NA

J Oleo Sci, 2013;62(9):695-708.
PMID: 24005014

The semi-empirical spectrophotometric (SESp) method, for the indirect determination of ion exchange constants (K(X)(Br)) of ion exchange processes occurring between counterions (X⁻ and Br⁻) at the cationic micellar surface, is described in this article. The method uses an anionic spectrophotometric probe molecule, N-(2-methoxyphenyl)phthalamate ion (1⁻), which measures the effects of varying concentrations of inert inorganic or organic salt (Na(v)X, v = 1, 2) on absorbance, (A(ob)) at 310 nm, of samples containing constant concentrations of 1⁻, NaOH and cationic micelles. The observed data fit satisfactorily to an empirical equation which gives the values of two empirical constants. These empirical constants lead to the determination of K(X)(Br) (= K(X)/K(Br) with K(X) and K(Br) representing cationic micellar binding constants of counterions X and Br⁻). This method gives values of K(X)(Br) for both moderately hydrophobic and hydrophilic X⁻. The values of K(X)(Br), obtained by using this method, are comparable with the corresponding values of K(X)(Br), obtained by the use of semi-empirical kinetic (SEK) method, for different moderately hydrophobic X. The values of K(X)(Br) for X = Cl⁻ and 2,6-Cl₂C6H₃CO₂⁻, obtained by the use of SESp and SEK methods, are similar to those obtained by the use of other different conventional methods.

Matched MeSH terms: Surface-Active Agents/chemistry*
Sodium dodecyl sulfate-coated-cationized agroforestry residue as adsorbent for benzene-adsorptive sequestration from aqueous solution

Kong H, Saman N, Tee PN, Cheu SC, Song ST, Johari K, et al.

Environ Sci Pollut Res Int, 2019 Apr;26(11):11140-11152.
PMID: 30796666 DOI: 10.1007/s11356-019-04248-5

The aim of this work is to convert agroforestry residue to a novel adsorbent (M-1CTA-SDS-BT) used for adsorptive benzene sequestration from aqueous solution. In this study, the anionic surfactant-coated-cationized banana trunk was synthesized and characterized for batch adsorption of benzene from aqueous solution. The surface morphology, surface chemistry, surface area, and pore properties of the synthesized adsorbents were examined. It was proven that surface cationization successfully increased the benzene adsorption capacity of sodium dodecyl sulfate-coated adsorbents. The Langmuir isotherm model satisfactorily described the equilibrium adsorption data. The maximum benzene adsorption capacity (qmax) of 468.19 μmol/g was attained. The kinetic data followed the pseudo-second-order kinetic model in which the rate-limiting step was proven to be the film diffusion. The batch-adsorbent regeneration results indicated that the M-1CTA-SDS-BT could withstand at least five adsorption/desorption cycles without drastic adsorption capacity reduction. The findings demonstrated the adsorptive potential of agroforestry-based adsorbent as a natural and cheap material for benzene removal from contaminated water.

Matched MeSH terms: Surface-Active Agents/chemistry
Stability-indicating micellar electrokinetic chromatography method for the analysis of sumatriptan succinate in pharmaceutical formulations

Al Azzam KM, Saad B, Tat CY, Mat I, Aboul-Enein HY

J Pharm Biomed Anal, 2011 Dec 15;56(5):937-43.
PMID: 21873014 DOI: 10.1016/j.jpba.2011.08.007

A micellar electrokinetic chromatography method for the determination of sumatriptan succinate in pharmaceutical formulations was developed. The effects of several factors such as pH, surfactant and buffer concentration, applied voltage, capillary temperature, and injection time were investigated. Separation took about 5 min using phenobarbital as internal standard. The separation was carried out in reversed polarity mode at 20 °C, 26 kV and using hydrodynamic injection for 10s. Separation was achieved using a bare fused-silica capillary 50 μm×40 cm and background electrolyte of 25 mM sodium dihydrogen phosphate-adjusted with concentrated phosphoric acid to pH 2.2, containing 125 mM sodium dodecyl sulfate and detection was at 226 nm. The method was validated with respect to linearity, limits of detection and quantification, accuracy, precision and selectivity. The calibration curve was linear over the range of 100-2000 μg mL(-1). The relative standard deviations of intra-day and inter-day precision for migration time, peak area, corrected peak area, ratio of corrected peak area and ratio of peak area were less than 0.68, 3.48, 3.28, 2.97 and 2.83% and 2.01, 5.50, 4.46, 4.92 and 4.07%, respectively. The proposed method was successfully applied to the determinations of the analyte in tablet. Forced degradation studies were conducted by introducing a sample of sumatriptan succinate standard solution to different forced degradation conditions using neutral (water), basic (0.1 M NaOH), acidic (0.1 M HCl), oxidative (10% H(2)O(2)) and photolytic (exposure to UV light at 254 nm for 2 h). It is concluded that the stability-indicating method for sumatriptan succinate can be used for the analysis of the drug in various samples.

Matched MeSH terms: Surface-Active Agents/chemistry
Sulfonated methyl esters of fatty acids in aqueous solutions: Interfacial and micellar properties

Danov KD, Stanimirova RD, Kralchevsky PA, Basheva ES, Ivanova VI, Petkov JT

J Colloid Interface Sci, 2015 Nov 1;457:307-18.
PMID: 26196714 DOI: 10.1016/j.jcis.2015.07.020

The interest to sulfonated methyl esters of fatty acids (SME) has been growing during the last decade, because these surfactants are considered as an environmentally friendly and renewable alternative of the linear alkyl-benzene sulfonates (LAS). Here, we present a quantitative study on the properties of aqueous SME solutions, and especially on their surface tension isotherms, critical micelle concentration (CMC) and its dependence on the concentration of added NaCl. It is demonstrated that the CMC of an ionic surfactant determined by electrical conductivity is insensitive to the presence of a small nonionic admixture, so that the CMC values determined by conductivity represent the CMC of the pure surfactant. Using SME as an example, we have demonstrated the application of a new and powerful method for determining the physicochemical parameters of the pure ionic surfactant by theoretical data analysis ("computer purification") if the used surfactant sample contains nonionic admixtures, which are present as a rule. This method involves fits of the experimental data for surface tension and conductivity by a physicochemical model based on a system of mass-balance, chemical-equilibrium and electric-double-layer equations, which allows us to determine the adsorption and micellization parameters of C12-, C14-, C16- and C18-SME, as well the fraction of nonionic admixtures (if any). Having determined these parameters, we can further predict the interfacial and micellization properties of the surfactant solutions, such as surface tension, adsorption, degree of counterion binding, and surface electric potential at every surfactant, salt and co-surfactant concentrations.

Matched MeSH terms: Surface-Active Agents/chemistry
Sulfonation of phenols extracted from the pyrolysis oil of oil palm shells for enhanced oil recovery

Awang M, Seng GM

ChemSusChem, 2008;1(3):210-4.
PMID: 18605208 DOI: 10.1002/cssc.200700083

The cost of chemicals prohibits many technically feasible enhanced oil recovery methods to be applied in oil fields. It is shown that by-products from oil palm processing can be a source of valuable chemicals. Analysis of the pyrolysis oil from oil palm shells, a by-product of the palm oil industry, reveals a complex mixture of mainly phenolic compounds, carboxylic acids, and aldehydes. The phenolic compounds were extracted from the pyrolysis oil by liquid-liquid extraction using alkali and an organic solvent and analyzed, indicating the presence of over 93% phenols and phenolic compounds. Simultaneous sulfonation and alkylation of the pyrolysis oil was carried out to produce surfactants for application in oil fields. The lowest measured surface tension and critical micelle concentration was 30.2 mNm(-1) and 0.22 wt%, respectively. Displacement tests showed that 7-14% of the original oil in place was recovered by using a combination of surfactants and xanthan (polymer) as additives.

Matched MeSH terms: Surface-Active Agents/chemistry
Fulltext Supramolecular Electrochemical Sensor for Dopamine Detection Based on Self-Assembled Mixed Surfactants on Gold Nanoparticles Deposited Graphene Oxide

Uppachai P, Srijaranai S, Poosittisak S, Md Isa I, Mukdasai S

Molecules, 2020 May 29;25(11).
PMID: 32485804 DOI: 10.3390/molecules25112528

A new supramolecular electrochemical sensor for highly sensitive detection of dopamine (DA) was fabricated based on supramolecular assemblies of mixed two surfactants, tetra-butylammonium bromide (TBABr) and sodium dodecyl sulphate (SDS), on the electrodeposition of gold nanoparticles on graphene oxide modified on glassy carbon electrode (AuNPs/GO/GCE). Self-assembled mixed surfactants (TBABr/SDS) were added into the solution to increase the sensitivity for the detection of DA. All electrodes were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The supramolecular electrochemical sensor (TBABr/SDS⋅⋅⋅AuNPs/GO/GCE) showed excellent electrocatalytic activity toward the oxidation of DA. Under the optimum conditions, the concentration of DA was obtained in the range from 0.02 µM to 1.00 µM, with a detection limit of 0.01 µM (3s/b). The results displayed that TBABr/SDS⋅⋅⋅AuNPs/GO/GCE exhibited excellent performance, good sensitivity, and reproducibility. In addition, the proposed supramolecular electrochemical sensor was successfully applied to determine DA in human serum samples with satisfactory recoveries (97.26% to 104.21%).

Matched MeSH terms: Surface-Active Agents/chemistry*
Surface active complexes formed between keratin polypeptides and ionic surfactants

Pan F, Lu Z, Tucker I, Hosking S, Petkov J, Lu JR

J Colloid Interface Sci, 2016 Dec 15;484:125-134.
PMID: 27599381 DOI: 10.1016/j.jcis.2016.08.082

Keratins are a group of important proteins in skin and hair and as biomaterials they can provide desirable properties such as strength, biocompatibility, and moisture regaining and retaining. The aim of this work is to develop water-soluble keratin polypeptides from sheep wool and then explore how their surface adsorption behaves with and without surfactants. Successful preparation of keratin samples was demonstrated by identification of the key components from gel electrophoresis and the reproducible production of gram scale samples with and without SDS (sodium dodecylsulphate) during wool fibre dissolution. SDS micelles could reduce the formation of disulphide bonds between keratins during extraction, reducing inter-molecular crosslinking and improving keratin polypeptide solubility. However, Zeta potential measurements of the two polypeptide batches demonstrated almost identical pH dependent surface charge distributions with isoelectric points around pH 3.5, showing complete removal of SDS during purification by dialysis. In spite of different solubility from the two batches of keratin samples prepared, very similar adsorption and aggregation behavior was revealed from surface tension measurements and dynamic light scattering. Mixing of keratin polypeptides with SDS and C12TAB (dodecyltrimethylammonium bromide) led to the formation of keratin-surfactant complexes that were substantially more effective at reducing surface tension than the polypeptides alone, showing great promise in the delivery of keratin polypeptides via the surface active complexes. Neutron reflection measurements revealed the coexistence of surfactant and keratin polypeptides at the interface, thus providing the structural support to the observed surface tension changes associated with the formation of the surface active complexes.

Matched MeSH terms: Surface-Active Agents/chemistry*
Surfactant-free solvothermal synthesis of Cu-MOF via protonation-deprotonation approach: A morphological dependent electrocatalytic activity for therapeutic drugs

Arul P, Huang ST, Gowthaman NSK, Govindasamy M, Jeromiyas N

Mikrochim Acta, 2020 11 09;187(12):650.
PMID: 33165679 DOI: 10.1007/s00604-020-04631-x

A copper-1,4-naphthalenedicarboxylic acid-based organic framework (Cu-NDCA MOF) with different morphologies was synthesized by solvothermal synthetic route via a simple protonation-deprotonation approach. The synthesized Cu-NDCA MOFs were analyzed by diverse microscopic and spectral techniques. The FE-SEM and TEM image results exhibited the flake-like (FL), partial anisotropic (PAT), and anisotropic (AT)-Cu-NDCA MOFs formation obtained at different pH (3.0, 7.0, and 9.0) of the reaction medium. The AT-Cu-NDCA MOF/GC electrode not only increases the electroactive surface area but also boosts the electron transfer rate reaction compared to other modified electrodes (PAT- and FL-Cu-NDCA MOFs/GCEs). Under the optimized conditions, the modified electrode (AT-Cu-NDCA MOF) exhibited a sharp oxidation peak (+ 0.46 V vs. Ag/AgCl) and higher current response for rutin. The electrode provides a wide linear range from 1 × 10-9 to 50 × 10-6 M, a low detection limit of 1.21 × 10-10 M, LOQ of 0.001 μM, and sensitivity of 0.149 μA μM-1 cm-2. The AT-Cu-NDCA MOF/GC electrode exhibited good stability (RSD = 3.52 ± 0.02% over 8 days of storage), and excellent reproducibility (RSD = 2.62 ± 0.02% (n = 3)). The modified electrode was applied to the determination of rutin in apple, orange, and lemon samples with good recoveries (99.79-99.91, 99.24-99.69, and 99.53-99.83, respectively). Graphical abstract Anisotropic structure of Cu-NDCA MOFs and its modification on glassy carbon electrode for ultra-sensitive determination of rutin in fruit samples.

Matched MeSH terms: Surface-Active Agents/chemistry*

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