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Enhanced water flux and bacterial resistance in cellulose acetate membranes with quaternary ammoniumpropylated polysilsesquioxane

Pandey RP, Kallem P, Rasheed PA, Mahmoud KA, Banat F, Lau WJ, et al.

Chemosphere, 2022 Feb;289:133144.
PMID: 34863730 DOI: 10.1016/j.chemosphere.2021.133144

An enhanced water flux and anti-fouling nanocomposite ultrafiltration membrane based on quaternary ammoniumpropylated polysilsesquioxane (QAPS)/cellulose acetate (QAPS@CA) was fabricated by in situ sol-gel processing via phase inversion followed by quaternization with methyl iodide (CH3I). Membrane characterizations were performed based on the contact angle, FTIR, SEM, and TGA properties. Membrane separation performance was assessed in terms of pure water flux, rejection, and fouling resistance. The 7%QAPS@CA nanocomposite membrane showed an increased wettability (46.6° water contact angle), water uptake (113%) and a high pure water permeability of ∼370 L m-2 h-1 bar-1. Furthermore, the 7%QAPS@CA nanocomposite membrane exhibited excellent bactericidal properties (∼97.5% growth inhibition) against Escherichia coli (E. coli) compared to the bare CA membrane (0% growth inhibition). The 7%QAPS@CA nanocomposite membrane can be recommended for water treatment and biomedical applications.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Recent Advances in Drug Delivery of Polymeric Nano-Micelles

Aziz ZABA, Ahmad A, Mohd-Setapar SH, Hassan H, Lokhat D, Kamal MA, et al.

Curr Drug Metab, 2017;18(1):16-29.
PMID: 27654898 DOI: 10.2174/1389200217666160921143616

In clinical studies, drugs with hydrophobic characteristic usually reflect low bioavailability, poor drug absorption, and inability to achieve the therapeutic concentration in blood. The production of poor solubility drugs, in abundance, by pharmaceutical industries calls for an urgent need to find the alternatives for resolving the above mentioned shortcomings. Poor water solubility drugs loaded with polymeric micelle seem to be the best alternative to enhance drugs solubility and bioavailability. Polymeric micelle, formed by self-assembled of amphiphilic block copolymers in aqueous environment, functioned as solubilizing agent for hydrophobic drug. This review discusses the fundamentals of polymeric micelle as drug carrier through representative literature, and demonstrates some applications in various clinical trials. The structure, characteristic, and formation of polymeric micelle have been discussed firstly. Next, this manuscript focuses on the potential of polymeric micelles as drug vehicle in oral, transdermal routes, and anti-cancer agent. Several results from previous studies have been reproduced in this review in order to prove the efficacy of the micelles in delivering hydrophobic drugs. Lastly, future strategies to broaden the application of polymeric micelles in pharmaceutical industries have been highlighted.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Fulltext Removal of metal ions and humic acids through polyetherimide membrane with grafted bentonite clay

Hebbar RS, Isloor AM, Prabhu B, Inamuddin, Asiri AM, Ismail AF

Sci Rep, 2018 03 16;8(1):4665.
PMID: 29549259 DOI: 10.1038/s41598-018-22837-1

Functional surfaces and polymers with branched structures have a major impact on physicochemical properties and performance of membrane materials. With the aim of greener approach for enhancement of permeation, fouling resistance and detrimental heavy metal ion rejection capacity of polyetherimide membrane, novel grafting of poly (4-styrenesulfonate) brushes on low cost, natural bentonite was carried out via distillation-precipitation polymerisation method and employed as a performance modifier. It has been demonstrated that, modified bentonite clay exhibited significant improvement in the hydrophilicity, porosity, and water uptake capacity with 3 wt. % of additive dosage. SEM and AFM analysis showed the increase in macrovoides and surface roughness with increased additive concentration. Moreover, the inclusion of modified bentonite displayed an increase in permeation rate and high anti-irreversible fouling properties with reversible fouling ratio of 75.6%. The humic acid rejection study revealed that, PEM-3 membrane having rejection efficiency up to 87.6% and foulants can be easily removed by simple hydraulic cleaning. Further, nanocomposite membranes can be significantly employed for the removal of hazardous heavy metal ions with a rejection rate of 80% and its tentative mechanism was discussed. Conspicuously, bentonite clay-bearing poly (4-styrenesulfonate) brushes are having a synergistic effect on physicochemical properties of nanocomposite membrane to enhance the performance in real field applications.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
The True Amphipathic Nature of Graphene Flakes: A Versatile 2D Stabilizer

Kuziel AW, Milowska KZ, Chau PL, Boncel S, Koziol KK, Yahya N, et al.

Adv Mater, 2020 Aug;32(34):e2000608.
PMID: 32672882 DOI: 10.1002/adma.202000608

The fundamental colloidal properties of pristine graphene flakes remain incompletely understood, with conflicting reports about their chemical character, hindering potential applications that could exploit the extraordinary electronic, thermal, and mechanical properties of graphene. Here, the true amphipathic nature of pristine graphene flakes is demonstrated through wet-chemistry testing, optical microscopy, electron microscopy, and density functional theory, molecular dynamics, and Monte Carlo calculations, and it is shown how this fact paves the way for the formation of ultrastable water/oil emulsions. In contrast to commonly used graphene oxide flakes, pristine graphene flakes possess well-defined hydrophobic and hydrophilic regions: the basal plane and edges, respectively, the interplay of which allows small flakes to be utilized as stabilizers with an amphipathic strength that depends on the edge-to-surface ratio. The interactions between flakes can be also controlled by varying the oil-to-water ratio. In addition, it is predicted that graphene flakes can be efficiently used as a new-generation stabilizer that is active under high pressure, high temperature, and in saline solutions, greatly enhancing the efficiency and functionality of applications based on this material.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Emerging era of "somes": polymersomes as versatile drug delivery carrier for cancer diagnostics and therapy

Sharma AK, Prasher P, Aljabali AA, Mishra V, Gandhi H, Kumar S, et al.

Drug Deliv Transl Res, 2020 Oct;10(5):1171-1190.
PMID: 32504410 DOI: 10.1007/s13346-020-00789-2

Over the past two decades, polymersomes have been widely investigated for the delivery of diagnostic and therapeutic agents in cancer therapy. Polymersomes are stable polymeric vesicles, which are prepared using amphiphilic block polymers of different molecular weights. The use of high molecular weight amphiphilic copolymers allows for possible manipulation of membrane characteristics, which in turn enhances the efficiency of drug delivery. Polymersomes are more stable in comparison with liposomes and show less toxicity in vivo. Furthermore, their ability to encapsulate both hydrophilic and hydrophobic drugs, significant biocompatibility, robustness, high colloidal stability, and simple methods for ligands conjugation make polymersomes a promising candidate for therapeutic drug delivery in cancer therapy. This review is focused on current development in the application of polymersomes for cancer therapy and diagnosis. Graphical abstract.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Enhanced activity of Candida antarctica lipase B in cholinium aminoate ionic liquids: a combined experimental and computational analysis

Chan KK, Sundaram V, Tan J, Ho YK, Ramanan RN, Ooi CW

J Biomol Struct Dyn, 2024;42(21):11351-11365.
PMID: 37787564 DOI: 10.1080/07391102.2023.2262590

As a class of ionic liquids with higher biocompatibility, cholinium aminoates ([Cho][AA]) hold potential as solvation media for enzymatic bioprocessing. Herein, solvation effect of [Cho][AA] on structural stability and enzymatic activity of Candida antarctica lipase B (CALB) was evaluated using experimental and computational approaches. Influence of [Cho][AA] on CALB stability was investigated using amino acid anions ([AA]-) with varying hydrophobicity levels. Choline phenylalaninate ([Cho][Phe]) resulted in 109.1% and 110.4% of relative CALB activity to buffer medium at 25 °C and 50 °C, respectively. Simulation results revealed the improvement of CALB's enzymatic activities by [AA]- with a strong hydrophobic character. Shielding of CALB from water molecules by [AA]- was observed. The level of CALB activity was governed by accumulation level of [AA]- at CALB's first hydration layer. The stronger interaction between His224 and Asp187 was postulated to be driven by [Cho][AA], resulting in the activity enhancement of CALB. The slight improvement of CALB activity in 0.05 M [Cho][Phe] at 50 °C could be due to the larger size of entrance to the catalytic site and the stronger interaction between the catalytic residues. The promising effect of [Cho][Phe] on CALB activation may stimulate research efforts in designing a 'fully green' bioreaction for various industrial applications.Communicated by Ramaswamy H. Sarma.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
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: Hydrophobic and Hydrophilic Interactions*
Fulltext Influence of chemical extraction conditions on the physicochemical and functional properties of polysaccharide gum from durian (Durio zibethinus) seed

Mirhosseini H, Amid BT

Molecules, 2012 May 29;17(6):6465-80.
PMID: 22643356 DOI: 10.3390/molecules17066465

Durian seed is an agricultural biomass waste of durian fruit. It can be a natural plant source of non-starch polysaccharide gum with potential functional properties. The main goal of the present study was to investigate the effect of chemical extraction variables (i.e., the decolouring time, soaking temperature and soaking time) on the physicochemical properties of durian seed gum. The physicochemical and functional properties of chemically-extracted durian seed gum were assessed by determining the particle size and distribution, solubility and the water- and oil-holding capacity (WHC and OHC). The present work revealed that the soaking time should be considered as the most critical extraction variable affecting the physicochemical properties of crude durian seed gum.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Fulltext Effect of surfactant and surfactant blends on pseudoternary phase diagram behavior of newly synthesized palm kernel oil esters

Mahdi ES, Sakeena MH, Abdulkarim MF, Abdullah GZ, Sattar MA, Noor AM

Drug Des Devel Ther, 2011;5:311-23.
PMID: 21792294 DOI: 10.2147/DDDT.S15698

The purpose of this study was to select appropriate surfactants or blends of surfactants to study the ternary phase diagram behavior of newly introduced palm kernel oil esters.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Physicochemical and sorption characteristics of Malaysian Ceiba pentandra (L.) Gaertn. as a natural oil sorbent

Abdullah MA, Rahmah AU, Man Z

J Hazard Mater, 2010 May 15;177(1-3):683-91.
PMID: 20060641 DOI: 10.1016/j.jhazmat.2009.12.085

Ceiba pentandra (L.) Gaertn (kapok) is a natural sorbent that exhibits excellent hydrophobic-oleophilic characteristics. The effect of packing density, the oil types and solvent treatment on the sorption characteristics of kapok was studied in a batch system. Oil sorption capacity, retention capacity, entrapment stability and kapok reusability were evaluated. Based on SEM and FTIR analyses, kapok fiber was shown to be a lignocellulosic material with hydrophobic waxy coating over the hollow structures. Higher packing density at 0.08 g/ml showed lower sorption capacity, but higher percentage of dynamic oil retention, with only 1% of oil drained out from the test cell. Kapok remained stable after fifteen cycles of reuse with only 30% of sorption capacity reduction. The oil entrapment stability at 0.08 g/ml packing was high with more than 90% of diesel and used engine oil retained after horizontal shaking. After 8h of chloroform and alkali treatment, 2.1% and 26.3% reduction in sorption capacity were observed, respectively, as compared to the raw kapok. The rigid hollow structure was reduced to flattened-like structure after alkali treatment, though no major structural difference was observed after chloroform treatment. Malaysian kapok has shown great potential as an effective natural oil sorbent, owing to high sorption and retention capacity, structural stability and high reusability.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Lipase immobilized on poly(VP-co-HEMA) hydrogel for esterification reaction

Basri M, Samsudin S, Ahmad MB, Razak CN, Salleh AB

Appl Biochem Biotechnol, 1999 Sep;81(3):205-17.
PMID: 15304777

Lipase from Candida rugosa was immobilized by entrapment on poly(N-vinyl- 2-pyrrolidone-co-2-hydroxyethyl methacrylate) (poly[VP-co-HEMA]) hydrogel, and divinylbenzene was the crosslinking agent. The immobilized enzymes were used in the esterification reaction of oleic acid and butanol in hexane. The activities of the immobilized enzymes and the leaching ability of the enzyme from the support with respect to the different compositions of the hydrogels were investigated. The thermal, solvent, and storage stability of the immobilized lipases was also determined. Increasing the percentage of composition of VP from 0 to 90, which corresponds to the increase in the hydrophilicity of the hydrogels, increased the activity of the immobilized enzyme. Lipase immobilized on VP(%):HEMA(%) 90:10 exhibited the highest activity. Lipase immobilized on VP(%):HEMA(%) 50:50 showed the highest thermal, solvent, storage, and operational stability compared to lipase immobilized on other compositions of hydrogels as well as the native lipase.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Fulltext The identification of novel Mycobacterium tuberculosis DHFR inhibitors and the investigation of their binding preferences by using molecular modelling

Hong W, Wang Y, Chang Z, Yang Y, Pu J, Sun T, et al.

Sci Rep, 2015;5:15328.
PMID: 26471125 DOI: 10.1038/srep15328

It is an urgent need to develop new drugs for Mycobacterium tuberculosis (Mtb), and the enzyme, dihydrofolate reductase (DHFR) is a recognised drug target. The crystal structures of methotrexate binding to mt- and h-DHFR separately indicate that the glycerol (GOL) binding site is likely to be critical for the function of mt-DHFR selective inhibitors. We have used in silico methods to screen NCI small molecule database and a group of related compounds were obtained that inhibit mt-DHFR activity and showed bactericidal effects against a test Mtb strain. The binding poses were then analysed and the influence of GOL binding site was studied by using molecular modelling. By comparing the chemical structures, 4 compounds that might be able to occupy the GOL binding site were identified. However, these compounds contain large hydrophobic side chains. As the GOL binding site is more hydrophilic, molecular modelling indicated that these compounds were failed to occupy the GOL site. The most potent inhibitor (compound 6) demonstrated limited selectivity for mt-DHFR, but did contain a novel central core (7H-pyrrolo[3,2-f]quinazoline-1,3-diamine), which may significantly expand the chemical space of novel mt-DHFR inhibitors. Collectively, these observations will inform future medicinal chemistry efforts to improve the selectivity of compounds against mt-DHFR.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Parametric Investigation of Batch Adsorption of Proteins onto Polymeric Particles

Tan MX, Agyei D, Pan S, Danquah MK

Curr Pharm Biotechnol, 2015;16(9):816-22.
PMID: 26119365

BACKGROUND: Effective bimolecular adsorption of proteins onto solid matrices is characterized by in-depth understanding of the biophysical features essential to optimize the adsorption performance.
RESULTS: The adsorption of bovine serum albumin (BSA) onto anion-exchange Q-sepharose solid particulate support was investigated in batch adsorption experiments. Adsorption kinetics and isotherms were developed as a function of key industrially relevant parameters such as polymer loading, stirring speed, buffer pH, protein concentration and the state of protein dispersion (solid/aqueous) in order to optimize binding performance and adsorption capacity. Experimental results showed that the first order rate constant is higher at higher stirring speed, higher polymer loading, and under alkaline conditions, with a corresponding increase in equilibrium adsorption capacity. Increasing the stirring speed and using aqueous dispersion protein system increased the adsorption rate, but the maximum protein adsorption was unaffected. Regardless of the stirring speed, the adsorption capacity of the polymer was 2.8 mg/ml. However, doubling the polymer loading increased the adsorption capacity to 9.4 mg/ml.
CONCLUSIONS: The result demonstrates that there exists a minimum amount of polymer loading required to achieve maximum protein adsorption capacity under specific process conditions.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Hydrophobic modification of cellulose isolated from Agave angustifolia fibre by graft copolymerisation using methyl methacrylate

Rosli NA, Ahmad I, Abdullah I, Anuar FH, Mohamed F

Carbohydr Polym, 2015 Jul 10;125:69-75.
PMID: 25857961 DOI: 10.1016/j.carbpol.2015.03.002

Graft copolymerisation of methyl methacrylate (MMA) onto Agave angustifolia was conducted with ceric ammonium nitrate (CAN) as the redox initiator. The maximum grafting efficiency was observed at CAN and MMA concentrations of 0.91 × 10(-3) and 5.63 × 10(-2)M, respectively, at 45°C for 3h reaction time. Four characteristic peaks at 2995, 1738, 1440, and 845 cm(-1), attributed to PMMA, were found in the IR spectrum of grafted cellulose. The crystallinity index dropped from 0.74 to 0.46, while the thermal stability improved upon grafting. The water contact angle increased with grafting yield, indicating increased hydrophobicity of cellulose. SEM images showed the grafted cellulose to be enlarged and rougher. The changes in the physical nature of PMMA-grafted cellulose can be attributed to the PMMA grafting in the amorphous regions of cellulose, causing it to expand at the expense of the crystalline component.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Fulltext Reinventing nano drug delivery systems for hydrophilic active ingredients in Ayurvedic lipid based formulations containing poly herbal decoction

Duraipandi S, Selvakumar V

J Ayurveda Integr Med, 2019 01 08;11(3):224-227.
PMID: 30635246 DOI: 10.1016/j.jaim.2018.01.008

BACKGROUND: Anu Tailam, an Ayurvedic medicated oil where 'anu' meant for atom and 'tailam' meant for oil and virtually meant for 'oil of subtle or atomic size particles'. Since the major active ingredients in this formulation are incorporated from the polyherbal decoction, it is expected to contain predominantly water soluble ingredients.
OBJECTIVES: It is hypothesized that these polar active botanical ingredients are present in the formulation should be either suspended in the form of submicron particles or entrapped in the submicron vesicular structures since the formulation did not show any precipitation or phase separation instead showed a monophasic oily liquid with very little moisture.
MATERIALS AND METHODS: In the present investigation, the micro architecture of the anu tailam is studied via column chromatography and high performance thin layer chromatography to prove the contents are polar hydrophilic compounds followed by optical microscopy, photon correlation Spectroscopy (PCS) and environmental scanning electron microscope (ESEM) to study the particle/vesicle size of the formulation.
RESULTS: In this study, it was proved that the formulation contained only polar ingredients and can be extracted in polar solvents like methanol and ethanol. It was also found that the formulation taken for study contained nano particles of the active botanical ingredients embedded in a network of vesicular structures of the lipid base.
CONCLUSION: The selected Ayurvedic formulation 'anutailam' found to contain novel nano drug delivery system to deliver water soluble ingredients across barriers.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Fulltext Influence of Multiwalled Carbon Nanotubes on the Rheological Behavior and Physical Properties of Kenaf Fiber-Reinforced Polypropylene Composites

Abdul Azam F', Razak Z, Md Radzi MKF, Muhamad N, Che Haron CH, Sulong AB

Polymers (Basel), 2020 Sep 13;12(9).
PMID: 32933225 DOI: 10.3390/polym12092083

The incorporation of kenaf fiber fillers into a polymer matrix has been pronounced in the past few decades. In this study, the effect of multiwalled carbon nanotubes (MWCNTs) with a short kenaf fiber (20 mesh) with polypropylene (PP) added was investigated. The melt blending process was performed using an internal mixer to produce polymer composites with different filler contents, while the suitability of this melt composite for the injection molding process was evaluated. Thermogravimetric analysis (TGA) was carried out to investigate the thermal stability of the raw materials. Rheological analyses were conducted by varying the temperature, load factor, and filler content. The results demonstrate a non-Newtonian pseudoplastic behavior in all samples with changed kenaf fillers (10 to 40 wt %) and MWCNT contents (1 to 4 wt %), which confirm the suitability of the feedstock for the injection molding process. The addition of MWCNTs had an immense effect on the viscosity and an enormous reduction in the feedstock flow behavior. The main contribution of this work is the comprehensive observation of the rheological characteristics of newly produced short PP/kenaf composites that were altered after MWCNT additions. This study also presented an adverse effect on the composites containing MWCNTs, indicating a hydrophilic property with improved water absorption stability and the low flammability effect of PP/kenaf/MWCNT composites. This PP/kenaf/MWCNT green composite produced through the injection molding technique has great potential to be used as car components in the automotive industry.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Fulltext Development of Polyvinylidene Fluoride Membrane by Incorporating Bio-Based Ginger Extract as Additive

Fahrina A, Arahman N, Mulyati S, Aprilia S, Mat Nawi NI, Aqsha A, et al.

Polymers (Basel), 2020 Sep 03;12(9).
PMID: 32899138 DOI: 10.3390/polym12092003

Biofouling on the membrane surface leads to performance deficiencies in membrane filtration. In this study, the application of ginger extract as a bio-based additive to enhance membrane antibiofouling properties was investigated. The extract was dispersed in a dimethyl acetamide (DMAc) solvent together with polyvinylidene fluoride (PVDF) to enhance biofouling resistance of the resulting membrane due to its antibiotic property. The concentrations of the ginger extract in the dope solution were varied in the range of 0-0.1 wt %. The antibacterial property of the resulting membranes was assessed using the Kirby Bauer disc diffusion method. The results show an inhibition zone formed around the PVDF/ginger membrane against Escherichia coli and Staphylococcus aureus demonstrating the efficacy of the residual ginger extract in the membrane matrix to impose the antibiofouling property. The addition of the ginger extract also enhanced the hydrophilicity in the membrane surface by lowering the contact angle from 93° to 85°, which was in good agreement with the increase in the pure water flux of up to 62%.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Fulltext Highly Sensitive Fluorescence Sensor for Carrageenan from a Composite Methylcellulose/Polyacrylate Membrane

Hassan RA, Heng LY, Tan LL

Sensors (Basel), 2020 Sep 04;20(18).
PMID: 32899886 DOI: 10.3390/s20185043

Carrageenans are linear sulphated polysaccharides that are commonly added into confectionery products but may exert a detrimental effect to human health. A new and simpler way of carrageenan determination based on an optical sensor utilizing a methylcellulose/poly(n-butyl acrylate) (Mc/PnBA) composite membrane with immobilized methylene blue (MB) was developed. The hydrophilic Mc polymer membrane was successfully modified with a more hydrophobic acrylic polymer. This was to produce an insoluble membrane at room temperature where MB reagent could be immobilized to build an optical sensor for carrageenan analysis. The fluorescence intensity of MB in the composite membrane was found to be proportional to the carrageenan concentrations in a linear manner (1.0-20.0 mg L-1, R2 = 0.992) and with a detection limit at 0.4 mg L-1. Recovery of spiked carrageenan into commercial fruit juice products showed percentage recoveries between 90% and 102%. The optical sensor has the advantages of improved sensitivity and better selectivity to carrageenan when compared to other types of hydrocolloids. Its sensitivity was comparable to most sophisticated techniques for carageenan analysis but better than other types of optical sensors. Thus, this sensor provides a simple, rapid, and sensitive means for carageenan analysis.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
A hysteresis-free perovskite transistor with exceptional stability through molecular cross-linking and amine-based surface passivation

Kim HP, Vasilopoulou M, Ullah H, Bibi S, Ximim Gavim AE, Macedo AG, et al.

Nanoscale, 2020 Apr 14;12(14):7641-7650.
PMID: 32207472 DOI: 10.1039/c9nr10745b

Organo-metal halide perovskite field-effect transistors present serious challenges in terms of device stability and hysteresis in the current-voltage characteristics. Migration of ions located at grain boundaries and surface defects in the perovskite film are the main reasons for instability and hysteresis issues. Here, we introduce a perovskite grain molecular cross-linking approach combined with amine-based surface passivation to address these issues. Molecular cross-linking was achieved through hydrogen bond interactions between perovskite halogens and dangling bonds present at grain boundaries and a hydrophobic cross-linker, namely diethyl-(12-phosphonododecyl)phosphonate, added to the precursor solution. With our approach, we obtained smooth and compact perovskite layers composed of tightly bound grains hence significantly suppressing the generation and migration of ions. Moreover, we achieved efficient surface passivation of the perovskite films upon surface treatment with an amine-bearing polymer, namely polyethylenimine ethoxylated. With our synergistic grain and surface passivation approach, we were able to demonstrate the first perovskite transistor with a complete lack of hysteresis and unprecedented stability upon continuous operation under ambient conditions. Added to the merits are its ambipolar transport of opposite carriers with balanced hole and electron mobilities of 4.02 and 3.35 cm2 V-1 s-1, respectively, its high Ion/Ioff ratio >104 and the lowest sub-threshold swing of 267 mV dec-1 reported to date for any perovskite transistor. These remarkable achievements obtained through a cost-effective molecular cross-linking of grains combined with amine-based surface passivation of the perovskite films open a new era and pave the way for the practical application of perovskite transistors in low-cost electronic circuits.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions
Fulltext Dry Thermotropic Glycolipid Self-Assembly:A Review

Hashim R, Zahid NI, Velayutham TS, Aripin NFK, Ogawa S, Sugimura A

J Oleo Sci, 2018 Jun 01;67(6):651-668.
PMID: 29760332 DOI: 10.5650/jos.ess17261

Also recognized as carbohydrate liquid crystals, glycolipids are amphiphiles whose basic unit comprises of a sugar group attached to an alkyl chain. Glycolipids are amphitropic, which means these materials form liquid crystal self-assemblies when dry (thermotropic) as well as when dissolved in solvents (lyotropic/surfactants) such as water. Many glycolipids are also naturally derived since these can be found in cell membranes. Their membrane and surfactant functions are largely understood through their lyotropic properties. While glycolipids are expected to play major roles as eco-friendly surfactants in the global surfactant market, their usefulness as thermotropic liquid crystal material is, to date, unknown, due to relatively lack of research performed and data reported in the literature. Understandably since glycolipids are hygroscopic with many hydroxy groups, removing the last trace water is very challenging. In recent time, with careful lyophilization and more consistent characterization technique, some researchers have attempted serious studies into "dry" or anhydrous glycolipids. Motivated by possible developments of novel thermotropic applications, some results from these studies also provide surprising new understanding to support conventional wisdom of the lyotropic systems. Here we review the dry state of glycosides, a family of glycolipids whose sugar headgroup is linked to the lipid chain via a glycosidic oxygen linker. The structure property relationship of both linear and anhydrous Guerbet glycosides will be examined. In particular, how the variation of sugar stereochemistry (e.g. anomer vs. epimer), the chain length and chain branching affect the formation of thermotropic liquid crystals phases, which not only located under equilibrium but also far from equilibrium conditions (glassy phase) are scrutinized. The dry glycolipid assembly has been subjected to electric and magnetic fields and the results show interesting behaviors including a possible transient current generation.

Matched MeSH terms: Hydrophobic and Hydrophilic Interactions

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