RESUMEN
Studying the adsorption behavior of cationic surfactants can help to develop more effective strategies to limit their dispersion in the environment. However, there have few studies on the adsorption of cationic surfactants from the perspective of critical micelle concentration (CMC). In this study, with cetyltrimethylammonium bromide (CTAB) and octadecyl trimethylammonium bromide (OTAB) serving as the model cationic surfactants, the effect of CMC on the adsorption behavior of cationic surfactant onto the surface of sodium alginate/silica (SA/SiO2) microspheres was systematically revealed. The adsorption mechanism relative to CMC was investigated under different conditions, including surfactant concentration, pH, temperature, and adsorption time. The results suggest that at identical concentrations, the smaller the CMC value of the cationic surfactants, the greater the adsorption amount (qt). qt for CTAB and OTAB were 583.2 and 678.0 mg/g respectively, with the concentration higher than their CMC value. When the concentration was lower than the CMC value of the cationic surfactants, qt for CTAB and OTAB were 123.2 and 138.7 mg/g, respectively. The CMC value of CTAB was lower than that of OTAB under identical conditions, suggesting that the adsorption of cationic surfactants is related to their CMC. These results are beneficial for the removal of cationic surfactants by adsorption methods.
Asunto(s)
Cationes , Micelas , Microesferas , Dióxido de Silicio , Tensoactivos , Tensoactivos/química , Adsorción , Dióxido de Silicio/química , Cationes/química , Cetrimonio/química , Compuestos de Cetrimonio/química , Alginatos/química , Concentración de Iones de HidrógenoRESUMEN
A highly sensitive micelle-induced sensory has been developed for detection of long-chain aldehydes as potential biomarkers of respiratory cancers. The micelle-like sensor was fabricated through the partial self-assembly of CTAB and S2 surfactants, containing a fluorescent hydrazine-functionalized dye (Naph-NH2). In principle, long-chain aldehydes with amphiphilic character act as the induced-fit surfactants to form well-entrapped micellar particles, as well as react with Naph-NH2 to form hydrazone derivatives resulting in fluorescent enhancement. The limit of detection (LOD) of micellar Naph-NH2/CTAB/S2 platform was calculated to be â¼ 64.09-80.98 µM for detection of long-chain aldehydes, which showed fluorescent imaging in lung cancer cells (A549). This micellar sensory probe demonstrated practical applicability for long-chain aldehyde sensing in human blood samples with an accepted percent recovery of ~ 94.02-102.4%. Beyond Naph-NH2/CTAB/S2 sensor, the milcellar hybrid sensor was successfully developed by incorporating a micelle-like platform with supramolecular gel regarding to carboxylate-based gelators (Gel1), which showed a tenfold improvement in sensitivity. Expectedly, the determination of long-chain aldehydes through these sensing platforms holds significant promise for point-of-care cancer diagnosis and therapy.
Asunto(s)
Aldehídos , Colorantes Fluorescentes , Hidrogeles , Límite de Detección , Micelas , Humanos , Aldehídos/química , Colorantes Fluorescentes/química , Hidrogeles/química , Células A549 , Hidrazinas/química , Cetrimonio/química , Tensoactivos/químicaRESUMEN
Norfloxacin (NOX), a broad spectrum fluoroquinolone (FQ) antibiotic, is commonly detected in environmental residues, potentially contributing to biological drug resistance. In this paper, an aptamer recognition probe has been used to develop a label-free liquid crystal-based biosensor for simple and robust optical detection of NOX in aqueous solutions. Stimuli-receptive liquid crystals (LCs) have been employed to report aptamer-target binding events at the LC-aqueous interface. The homeotropic alignment of LCs at the aqueous-LC interface is due to the self-assembly of the cationic surfactant cetyltrimethylammonium bromide (CTAB). In the presence of the negatively charged NOX aptamer, the ordering changes to planar/tilted. On addition of NOX, the aptamer-NOX binding causes redistribution of CTAB at the LC-aqueous interface and the homeotropic orientation is restored. This results in a bright-to-dark optical transition under a polarized optical microscope (POM). This optical transition serves as a visual indicator to mark the presence of NOX. The devised aptasensor demonstrates high specificity with a minimum detection limit of 5 nM (1.596 ppb). Moreover, the application of the developed aptasensor for the detection of NOX in freshwater and soil samples underscores its practical utility in environmental monitoring. This proposed LC-based method offers several advantages over conventional detection techniques for a rapid, feasible and convenient way to detect norfloxacin.
Asunto(s)
Aptámeros de Nucleótidos , Técnicas Biosensibles , Lagos , Límite de Detección , Cristales Líquidos , Norfloxacino , Norfloxacino/análisis , Norfloxacino/química , Aptámeros de Nucleótidos/química , Cristales Líquidos/química , Lagos/análisis , Lagos/química , Técnicas Biosensibles/métodos , Suelo/química , Antibacterianos/análisis , Antibacterianos/química , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/química , Cetrimonio/químicaRESUMEN
Several studies have demonstrated that air-bubbling and foam fractionation techniques can efficiently remove long-chain PFAS from contaminated water. However, removing short-chain PFAS is challenging due to its lower surface activity and inability to form self-assembly structures at the air-water interface. In this study, we tested various additives, including salts, surfactants, and polymers, to improve short-chain PFAS (e.g., perfluorobutanesulfonic acid (PFBS) and perfluorobutanoic acid (PFBA)) removal in non-foaming solutions using a bench-scale system. We found that in the presence of cetyltrimethylammonium chloride (CTAC) and salt, air-bubbling can significantly remove 0.5 µg L-1 of PFBS and PFBA in deionized water by >99% (15 min) and 81% (60 min), respectively. The decline of surface tension and the formation of thin foam-like layers during bubbling, controlled by the concentration of CTAC, significantly improved the removal of short-chain PFAS. Adding anionic and neutral surfactants showed no removal of short-chain PFAS during bubbling, suggesting the importance of the electrostatic interactions between short-chain PFAS and the cationic CTAC. We observed a 1:1 M ratio between CTAC and PFBS removed from the solution, suggesting the formation of ion pairs in the solution and enhancing the surface activity of the overall neutral (PFAS-CTAC) complex. A mass balance of the system revealed that the primary mechanism by which PFAS was removed from non-foaming waters was through aerosol generation (70-100%). Using the optimized condition, PFAS mixtures (short- and long-chain PFAS, including five recently regulated PFAS by USPEA, 2 nM each) in deionized water and natural groundwater were successfully removed to below detection (>99% removal; <2 ng L-1), except for PFBA (25-73% removal). These results provide an improved understanding of the mechanism by which PFAS is removed during foam fractionation and highlight the need for capturing aerosols enriched with PFAS to prevent secondary contamination.
Asunto(s)
Fluorocarburos , Tensoactivos , Contaminantes Químicos del Agua , Fluorocarburos/química , Tensoactivos/química , Contaminantes Químicos del Agua/química , Cationes/química , Fraccionamiento Químico/métodos , Cetrimonio/química , Purificación del Agua/métodos , Agua/química , Ácidos SulfónicosRESUMEN
SshEstI, a carboxylesterase from the thermoacidophilic archaeon Saccharolobus shibatae, is a member of the hormone-sensitive lipase family that displays slightly alkaliphilic activity with an optimum activity at pH 8.0. In this study, three distinct strategies were explored to confer acidophilic properties to SshEstI. The first strategy involved engineering the oxyanion hole by replacing Gly81 with serine or aspartic acid. The G81S mutant showed optimum activity at pH 7.0, whereas the aspartic acid mutant (G81D) rendered the enzyme slightly acidophilic with optimum activity observed at pH 6.0; however, kcat and kcat/Km values were reduced by these substitutions. The second strategy involved examining the effects of surfactant additives on the pH-activity profiles of SshEstI. The results showed that cetyltrimethylammonium bromide (CTAB) enhanced wild-type enzyme (WT) activity at acidic pH values. In the presence of 0.1 mM CTAB, G81S and G81D were acidophilic enzymes with optimum activity at pH 6.0 and 4.0, respectively, although their enzyme activities were low. The third strategy involved engineering the active site to resemble that of kumamolisin-As (kuma-As), an acidophilic peptidase of the sedolisin family. The catalytic triad of kuma-As was exchanged into SshEstI using site-directed mutagenesis. X-ray crystallographic analysis of the mutants (H274D and H274E) revealed that the potential hydrogen donor-acceptor distances around the active site of WT were fully maintained in these mutants. However, these mutants were inactive at pH 4-8.
Asunto(s)
Dominio Catalítico , Concentración de Iones de Hidrógeno , Esterol Esterasa/química , Esterol Esterasa/metabolismo , Esterol Esterasa/genética , Cetrimonio/química , Tensoactivos/farmacología , Tensoactivos/química , Tensoactivos/metabolismo , Cinética , Proteínas Arqueales/metabolismo , Proteínas Arqueales/química , Proteínas Arqueales/genética , Mutagénesis Sitio-Dirigida , Carboxilesterasa/metabolismo , Carboxilesterasa/química , Carboxilesterasa/genética , Estabilidad de EnzimasRESUMEN
Although rare, amoebic keratitis (AK) is a disease caused by Acanthamoeba spp. that can lead to blindness. The drugs currently available for its treatment are very toxic, which has motivated the investigation for more effective and safe therapeutic options. In this study, the in vitro activity of ß-caryophyllene (BCP) was exploited taking into account its action against other protozoans as well as its well-known healing and anti-inflammatory properties (aspects relevant for the AK pathogenesis). On the other hand, high volatilization and oxidation phenomena are found for this compound, which led to its incorporation into nanoemulsions (NEs). Two emulsifying agents were tested, resulting in monodisperse systems with reduced droplet size (<265 nm) and high surface charge (positive and negative for NEs prepared with cetrimonium bromide -CTAB and Phosal® 50+, respectively). NEs prepared with CTAB were shown to be more stable after long-term storage at 4 and 25 °C than those prepared with Phosal®. Pure BCP, at the highest concentration (500 µM), resulted in a level of inhibition of Acanthamoeba trophozoites equivalent to that of reference drug (chlorhexidine). This activity was even greater after oil nanoencapsulation. The reduced droplet size could improve the interaction of the oil with the microorganism, justifying this finding. Changes in surface charge did not impact the activity. Positively charged NEs improved the interaction and retention of BCP in the cornea and thus should be prioritized for further studies.
Asunto(s)
Queratitis por Acanthamoeba , Emulsiones , Sesquiterpenos Policíclicos , Queratitis por Acanthamoeba/tratamiento farmacológico , Queratitis por Acanthamoeba/parasitología , Sesquiterpenos Policíclicos/química , Nanopartículas , Administración Oftálmica , Cetrimonio/química , Animales , Acanthamoeba/efectos de los fármacos , Estabilidad de Medicamentos , Tamaño de la Partícula , Soluciones Oftálmicas , HumanosRESUMEN
In this study, UV-vis spectroscopy was employed to investigate the interaction between formylphenoxyacetic acid (FPAA) and its derivatives (chalcone and flavones) with ionic surfactants (SDS, CTAB, and DTAB) in different physiological environments. Changes in the physiochemical properties of FPAA chalcone and flavones including binding constants, partitioning constants, and Gibbs free energy were observed which were influenced by the presence of ionic surfactants computed using mathematical models. The solubilization of the targeted compounds in the ionic surfactants was determined through the binding constant (Kb). The results of the present study indicated that electrostatic interactions played a significant role in the solubilization of the targeted compounds in SDS, CTAB, and DTAB. At pH 4.1, FPAA chalcone exhibited stronger binding affinity with SDS compared to CTAB and DTAB. However, at pH 7.4, chalcone showed stronger binding with DTAB compared to SDS, while negligible interaction with CTAB was observed at pH 7.4. The flavones demonstrated stronger binding with DTAB at pH 7.4 compared to SDS and CTAB and it exhibited strong bonding with CTAB at pH 4.1. The negative values of the Gibbs free energy for binding (ΔGbË) and partitioning (ΔGpË) constants displayed the spontaneity of the process. However, FPAA chalcone with SDS and FPAA flavones with DTAB furnished positive ΔGbË, indicating a non-spontaneous process.
Asunto(s)
Flavonas , Solubilidad , Tensoactivos , Tensoactivos/química , Flavonas/química , Flavonas/metabolismo , Concentración de Iones de Hidrógeno , Cetrimonio/química , Termodinámica , Iones/química , Chalcona/química , Chalconas/química , Chalconas/metabolismo , Dodecil Sulfato de Sodio/química , Electricidad EstáticaRESUMEN
The surfactant cetyltrimethylammonium bromide (CTAB) induces the aggregation of gold nanoclusters (GNCs), leading to the development of a proposed fluorometric technique for detecting thiocyanate (SCN-) ions based on an anti-aggregation mechanism. This approach is straightforward to execute, highly sensitive, and selective. A significant quenching effect occurs in fluorescence upon using the aggregation agent CTAB in GNCs synthesis, resulting in a transition from intense red fluorescence to dim red. The decrease in fluorescence intensity of GNCs in the presence of CTAB is caused by the mechanism of fluorescence quenching mediated by aggregation. As the levels of SCN- rise, the fluorescence of CTAB-GNCs increases; this may be detected using spectrofluorometry or by visually inspecting under UV irradiation. The recovery of red fluorescence of CTAB-GNCs in the presence of SCN- enables the precise and discerning identification of SCN- within the concentration range of 2.86-140 nM. The minimum detectable concentration of the SCN- ions was 1 nM. The selectivity of CTAB-GNCs towards SCN- ions was investigated compared to other ions, and it was demonstrated that CTAB-GNCs exhibit exceptional selectivity. Furthermore, we believe that CTAB-GNCs have novel possibilities as favorable sensor candidates for various industrial applications. Our detection technique was validated by analyzing SCN- ions in milk samples, which yielded promising results.
Asunto(s)
Cetrimonio , Oro , Nanopartículas del Metal , Tiocianatos , Oro/química , Nanopartículas del Metal/química , Cetrimonio/química , Espectrometría de Fluorescencia , Industria de Alimentos , Técnicas Biosensibles , IonesRESUMEN
This study explores the dual applications of a greenly synthesized ZnO@CTAB nanocomposite for the efficient remediation of Rhodamine B (RhB) and lead (Pb). The synthesis method involves a sustainable approach, emphasizing environmentally friendly practices. FT-IR, XRD, FESEM, zeta potential, and particle size analyzer (PSA), BET, and UV-VIS were used to physically characterize the zinc oxide and CTAB nanocomposite (ZnO@CTAB). The size and crystalline index of ZnO@CTAB are 77.941 nm and 63.56% respectively. The Zeta potential of ZnO@CTAB is about - 22.4 mV. The pore diameter of the ZnO@CTAB was 3.216 nm, and its total surface area was 97.42 m2/g. The mechanism of adsorption was investigated through pHZPC measurements. The nanocomposite's adsorption performance was systematically investigated through batch adsorption experiments. At pH 2, adsorbent dose of 0.025 g, and temperature 50 °C, ZnO@CTAB removed the most RhB, while at pH 6, adsorbent dose of 0.11 g, and temperature 60 °C, ZnO@CTAB removed the most Pb. With an adsorption efficiency of 214.59 mg/g and 128.86 mg/g for RhB and Pb, the Langmuir isotherm model outperforms the Freundlich isotherm model in terms of adsorption. The pseudo-2nd-order model with an R2 of 0.99 for both RhB and Pb offers a more convincing explanation of adsorption than the pseudo-1st-order model. The results demonstrated rapid adsorption kinetics and high adsorption capacities for RhB and Pb. Furthermore, there was minimal deterioration and a high reusability of ZnO@CTAB till 4 cycles were observed.
Asunto(s)
Plomo , Nanocompuestos , Rodaminas , Contaminantes Químicos del Agua , Óxido de Zinc , Plomo/química , Óxido de Zinc/química , Rodaminas/química , Nanocompuestos/química , Contaminantes Químicos del Agua/química , Adsorción , Cetrimonio/química , Restauración y Remediación Ambiental/métodos , Tecnología Química Verde , Nanoestructuras/químicaRESUMEN
AIM: The antifungal activity was studied on sessile and persister cells (PCs) of Candida tropicalis biofilms of gold nanoparticles (AuNPs) stabilized with cetyltrimethylammonium bromide (CTAB-AuNPs) and those conjugated with cysteine, in combination with Amphotericin B (AmB). MATERIALS/METHODS: The PC model was used and synergistic activity was tested by the checkerboard assay. Biofilms were studied by crystal violet and scanning electron microscopy. RESULTS/CONCLUSIONS: After the combination of both AuNPs and AmB the biofilm biomass was reduced, with significant differences in architecture being observed with a reduced biofilm matrix. In addition, the CTAB-AuNPs-AmB combination significantly reduced PCs. Understanding how these AuNPs aid in the fight against biofilms and the development of new approaches to eradicate PCs has relevance for chronic infection treatment.
Asunto(s)
Anfotericina B , Antifúngicos , Biopelículas , Candida tropicalis , Sinergismo Farmacológico , Oro , Nanopartículas del Metal , Pruebas de Sensibilidad Microbiana , Candida tropicalis/efectos de los fármacos , Oro/química , Oro/farmacología , Biopelículas/efectos de los fármacos , Anfotericina B/farmacología , Anfotericina B/química , Nanopartículas del Metal/química , Antifúngicos/farmacología , Antifúngicos/química , Cetrimonio/química , Compuestos de Cetrimonio/farmacología , Compuestos de Cetrimonio/químicaRESUMEN
Gold nanorods (AuNRs) with unique optical properties play a pivotal role in applications in plasmonic imaging, small molecule detection, and photothermal therapy. However, challenges in DNA functionalization of AuNRs hinder their full potential due to the presence of a dense cetyltrimethylammonium bromide (CTAB) bilayer, impeding close DNA contact. In this study, we introduced a convenient approach for the rapid assembly of polyadenine (polyA) tailed DNA on AuNRs with control of DNA density, rigidity, and valence. We explored the impact of DNA with designed properties on the construction of core-satellite structures by employing AuNRs as cores and spherical gold nanoparticles (AuNSs) as satellites. Density, rigidity, and valence are identified as crucial factors for efficient construction. Specifically, polyA-tailed DNA modulated DNA density and reduced spatial hindrance and electrostatic repulsion, thereby facilitating the construction. Enhancing the rigidity of DNA and incorporating multiple binding sites can further improve the efficiency.
Asunto(s)
ADN , Oro , Nanotubos , Poli A , Oro/química , Nanotubos/química , ADN/química , Poli A/química , Nanopartículas del Metal/química , Cetrimonio/químicaRESUMEN
Wastewater-based epidemiology has allowed tracking the magnitude and distribution of SARS-CoV-2 in communities, allowing public health officials to prepare for impending outbreaks. While many factors influence recovery of SARS-CoV-2 from wastewater, proper extraction, concentration, and purification of RNA are key steps to ensure accurate detection of viral particles. The aim of this study was to compare the efficiency of four commonly used RNA extraction methods for detection of the SARS-CoV-2 RNA genome in sewage samples artificially inoculated with the virus, in order to identify a protocol that improves viral recovery. These methods included CTAB-based, TRIzol-based, and guanidinium thiocyanate (GTC)-based extraction procedures coupled with silica spin column-based purification, and an automated extraction/purification protocol using paramagnetic particles. Following RNA extraction, virus recovery rates were compared using RT-qPCR-based detection. The CTAB-based approach yielded the highest recovery rates and was the only method to consistently demonstrate stable virus recovery percentages regardless of the specific physicochemical characteristics of the samples tested. The TRIzol method proved to be the second most effective, yielding significantly higher recovery rates compared to both the GTC-based and the automated extraction methods. These results suggest that the CTAB-based approach could be a useful tool for the recovery of viral RNA from complex wastewater matrices.
Asunto(s)
Cetrimonio , ARN Viral , SARS-CoV-2 , Aguas Residuales , Aguas Residuales/virología , ARN Viral/aislamiento & purificación , ARN Viral/genética , SARS-CoV-2/aislamiento & purificación , SARS-CoV-2/genética , Cetrimonio/química , Humanos , Compuestos de Cetrimonio/química , COVID-19/virología , COVID-19/diagnóstico , Tiocianatos , Aguas del Alcantarillado/virología , GuanidinasRESUMEN
While most household surfactants are biodegradable in aerobic conditions, their biodegradability may obscure their environmental risks. The presence of surfactants in a biological treatment process can lead to the proliferation of antimicrobial-resistance genes (ARG) in the biomass. Surfactants can be cationic, anionic, or zwitterionic, and these different classes may have different effects on the proliferation ARG. Cationic hexadecyltrimethyl-ammonium (CTAB), anionic sodium dodecyl sulfate (SDS), and zwitterionic 3-(decyldimethylammonio)-propanesulfonate inner salt (DAPS) were used to represent the three classes of surfactants in domestic household clean-up products. This study focused on the removal of these surfactants by the O2-based Membrane Biofilm Reactor (O2-MBfR) for hotspot scenarios (â¼1 mM) and how the three classes of surfactants affected the microbial community's structure and ARG. Given sufficient O2 delivery, the MBfR provided at least 98% surfactant removal. The presence and biodegradation for each surfactant uniquely shaped the biofilms' microbial communities and the presence of ARG. CTAB had by far the strongest impact and the higher ARG abundance. In particular, Pseudomonas and Stenotrophomonas, the two main genera in the biofilm treating CTAB, were highly correlated to the abundance of ARG for efflux pumps and antibiotic inactivation. CTAB also led to more functional genes relevant to the Type-IV secretion system and protection against oxidative stress, which also could encourage horizontal gene transfer. Our findings highlight that the biodegradation of quaternary ammonium surfactants, while beneficial, can pose public health concerns from its ability to promote the proliferation of ARG.
Asunto(s)
Antiinfecciosos , Tensoactivos , Tensoactivos/química , Antibacterianos , Cetrimonio/química , Transferencia de Gen Horizontal , Farmacorresistencia Bacteriana/genética , Compuestos de Amonio Cuaternario/químicaRESUMEN
In this research, real-time monitoring of lipid membrane disruption is made possible by exploiting the dynamic properties of model lipid bilayers formed at oil-water interfaces. This involves tracking an electrical signal generated through rhythmic membrane perturbation translated into the adsorption and penetration of charged species within the membrane. Importantly, this allows for the detection of membrane surface interactions that occur prior to pore formation that may be otherwise undetected. The requisite dynamic membranes for this approach are made possible through the droplet interface bilayer (DIB) technique. Membranes are formed at the interface of lipid monolayer-coated aqueous droplets submerged in oil. We present how cyclically alternating the membrane area leads to the generation of mechanoelectric current. This current is negligible without a transmembrane voltage until a composition mismatch between the membrane monolayers is produced, such as a one-sided accumulation of disruptive agents. The generated mechanoelectric current is then eliminated when an applied electric field compensates for this asymmetry, enabling measurement of the transmembrane potential offset. Tracking the compensating voltage with respect to time then reveals the gradual accumulation of disruptive agents prior to membrane permeabilization. The innovation of this work is emphasized in its ability to continuously track membrane surface activity, highlighting the initial interaction steps of membrane disruption. In this paper, we begin by validating our proposed approach against measurements taken for fixed composition membranes using standard electrophysiological techniques. Next, we investigate surfactant adsorption, including hexadecyltrimethylammonium bromide (CTAB, cationic) and sodium decyl sulfate (SDS, anionic), demonstrating the ability to track adsorption prior to disruption. Finally, we investigate the penetration of lipid membranes by melittin, confirming that the peptide insertion and disruption mechanics are, in part, modulated by membrane composition.
Asunto(s)
Membrana Dobles de Lípidos/metabolismo , Cetrimonio/química , Capacidad Eléctrica , Electrofisiología/métodos , Membrana Dobles de Lípidos/química , Meliteno/química , Meliteno/metabolismo , Permeabilidad , Fosfatidilcolinas/química , Fosfatidilcolinas/metabolismo , Dodecil Sulfato de Sodio/química , Electricidad Estática , Tensoactivos/químicaRESUMEN
Silica-coated gold nanorods (AuNRs) exhibit significantly enhanced photothermal effects and photoacoustic (PA) signal intensities, which is beneficial for various nanophotonic applications in materials science. However, the silica shell thickness for optimum enhancement is not fully understood and is even controversial depending on the physical state of the silica shell. This is because of the lack of systematic investigations of the nanoscale silica shell thickness and the photothermal effect. This study provides a robust synthetic method to control the silica shell thickness at the nanoscale and the physical state-dependent heat diffusion property. The selected base and solvent system enabled the production of silica-coated AuNRs (AuNR@SiO2) with silica shell thicknesses of 5, 10, 15, 20, 25, 30, 35, and 40 nm. AuNRs with a 20 nm silica shell showed the highest photothermal effect with a 1.45-times higher photothermal efficiency than that of AuNRs without a silica shell. The low density of the silica shell on the AuNRs showed a low photothermal effect and photostability. It was found that the disruption of cetyltrimethyl ammonium bromide (CTAB) layers on the AuNRs was responsible for the low photostability of the AuNRs. The simulation study for the heat diffusion property showed facilitated heat diffusion in the presence of a 20 nm silica shell. In a cell-based study, AuNRs with a 20 nm silica shell showed the most sensitive photothermal effect for cell death. The results of this robust study can provide conclusive conditions for the optimal silica shell thickness to obtain the highest photothermal effect, which will be useful for the future design of nanomaterials in various fields of application.
Asunto(s)
Nanotubos/química , Dióxido de Silicio/química , Muerte Celular/efectos de los fármacos , Línea Celular Tumoral , Cetrimonio/química , Transferencia de Energía , Oro/química , Oro/efectos de la radiación , Humanos , Rayos Infrarrojos , Nanotubos/efectos de la radiación , Terapia Fototérmica , Dióxido de Silicio/efectos de la radiaciónRESUMEN
Mesoporous silica network nanotubes were fabricated using both organic and inorganic templates such as citric acid (CA), cetyltrimethylammonium bromide (CTAB), and sodium bicarbonate (SBC). The phase analysis of synthesized silica network was confirmed by X-ray diffractometer (XRD) analysis, and the present functional groups were revealed by Fourier Transform Infrared Spectroscopy (FTIR) and the formation of tubular morphology was analyzed by transmission electron microscopy (TEM). The mesoporous nature of each template sample was studied using Brunauer-Emmett-Teller (BET) instrument. The surface area and porous size were calculated successfully for fabricated silica network nanotubes.
Asunto(s)
Nanotubos/química , Dióxido de Silicio/química , Cetrimonio/química , Ácido Cítrico/química , Porosidad , Bicarbonato de Sodio/químicaRESUMEN
In this work, a novel composite carrier system for loading essential oils was developed by using tetraethyl orthosilicate (TEOS) and (3-aminopropyl) triethoxysilane (APTES) as silica precursors and cetyl trimethyl ammonium bromide (CTAB) as a template, and the resultant aminated mesoporous silica was further chemically modified by polyacrylic acid (PAA). The obtained composite carriers exhibited a high loading capability toward tea tree oil (TTO), and they also significantly improved the release behavior of TTO due to the steric hindrance of silica mesopore and the polymer restriction. Besides, it was found that the release behavior followed the First-Order kinetic model, revealing that the release of TTO was driven by the concentration gradient. In addition, these composite carriers with essential oil-loaded demonstrated remarkable antibacterial performance againstE. coliandS. aureus, and they could retain antibacterial performance even after 50 d. Moreover, the antibacterial mechanism was also elucidated with the assistance of nucleic acid and conductivity measurements. Therefore, this work provides a facile and environmentally friendly approach to preparing effective composite carriers for improving the sustained release of essential oils, and the long-term antibacterial performance of these essential oil-loaded composite carriers makes them tremendously potential for practical applications.
Asunto(s)
Antibacterianos/química , Portadores de Fármacos/química , Nanocompuestos/química , Aceites Volátiles/química , Dióxido de Silicio/química , Resinas Acrílicas/química , Antibacterianos/farmacología , Cetrimonio/química , Preparaciones de Acción Retardada , Liberación de Fármacos , Escherichia coli/efectos de los fármacos , Aceites Volátiles/farmacología , Porosidad , Propilaminas/química , Silanos/química , Staphylococcus aureus/efectos de los fármacosRESUMEN
Surfactant aggregates have long been considered as a tool to improve drug delivery and have been widely used in medical products. The pH-responsive aggregation behavior in anionic gemini surfactant 1,3-bis(N-dodecyl-N-propanesulfonate sodium)-propane (C12C3C12(SO3)2) and its mixture with a cationic monomeric surfactant cetyltrimethylammonium bromide (CTAB) have been investigated. The spherical-to-wormlike micelle transition was successfully realized in C12C3C12(SO3)2 through decreasing the pH, while the rheological properties were perfectly enhanced for the formation of wormlike micelles. Especially at 140 mM and pH 6.7, the mixture showed high viscoelasticity, and the maximum of the zero-shear viscosity reached 1530 Pa·s. Acting as a sulfobetaine zwitterionic gemini surfactant, the electrostatic attraction, the hydrogen bond and the short spacer of C12C3C12(SO3)2 molecules were all responsible for the significant micellar growth. Upon adding CTAB, the similar transition could also be realized at a low pH, and the further transformation to branched micelles occurred by adjusting the total concentration. Although the mixtures did not approach the viscosity maximum appearing in the C12C3C12(SO3)2 solution, CTAB addition is more favorable for viscosity enhancement in the wormlike-micelle region. The weakened charges of the headgroups in a catanionic mixed system minimizes the micellar spontaneous curvature and enhances the intermolecular hydrogen-bonding interaction between C12C3C12(SO3)2, facilitating the formation of a viscous solution, which would greatly induce entanglement and even the fusion of wormlike micelles, thus resulting in branched microstructures and a decline of viscosity.
Asunto(s)
Reología , Tensoactivos/química , Cetrimonio/química , Glutamatos/química , Concentración de Iones de Hidrógeno , Micelas , ViscosidadRESUMEN
Cationic surfactants interact with DNA (Deoxyribonucleic acid), forming surfactant-DNA complexes that offer particularly efficient control for encapsulation and release of DNA from DNA gel particles. In the present work, DNA-based particles were prepared using CTAB (Cetyltrimethylammonium bromide) as the cationic surfactant and modified using two different additives: (Multi-Walled Carbon Nanotubes) MWNT or PEG (Poly Ethylene Glycol). The use of both additives to form composites increased the stability of the gel particles. The stability was monitored by the release of DNA and CTAB in different pH solutions. However, not much is known about the influence of pH on DNA-surfactant interaction and the release of DNA and surfactant from gel particles. It was observed that the solubilization of DNA occurs only in very acid media, while that of CTAB does not depend on pH and gets to a plateau after about 8 h. Within 2 h in contact with a pH = 2 solution, about 1% DNA and CTAB was released. Complete destruction for the gel particles was observed in pH = 2 solution after 17 days for PEG and 20 days for MWNT. The composite particles show a considerably enlarged sustained release span compared to the unmodified ones. The dehydration-rehydration studies show that the structure of the composite gel particles, as determined from SAXS (Small-Angle-X-Ray-Scattering) experiments, is similar to that of the unmodified ones. These studies will allow a better knowledge of these particles' formation and evolution in view of possible applications in drug delivery and release.
Asunto(s)
Cetrimonio/química , ADN/química , Nanotubos de Carbono/química , Tensoactivos/química , Geles , Concentración de Iones de Hidrógeno , Polietilenglicoles , Dispersión del Ángulo Pequeño , Difracción de Rayos XRESUMEN
BACKGROUND: Although laccase has a good catalytic oxidation ability, free laccase shows a poor stability. Enzyme immobilization is a common method to improve enzyme stability and endow the enzyme with reusability. Adsorption is the simplest and common method. Modified biochar has attracted great attention due to its excellent performance. RESULTS: In this paper, cetyltrimethylammonium bromide (CTAB)-KOH modified biochar (CKMB) was used to immobilize laccase by adsorption method (laccase@CKMB). Based on the results of the single-factor experiments, the optimal loading conditions of laccase@CKMB were studied with the assistance of Design-Expert 12 and response surface methods. The predicted optimal experimental conditions were laccase dosage 1.78 mg/mL, pH 3.1 and 312 K. Under these conditions, the activity recovery of laccase@CKMB was the highest, reaching 61.78%. Then, the CKMB and laccase@CKMB were characterized by TGA, FT-IR, XRD, BET and SEM, and the results showed that laccase could be well immobilized on CKMB, the maximum enzyme loading could reach 57.5 mg/g. Compared to free laccase, the storage and pH stability of laccase@CKMB was improved greatly. The laccase@CKMB retained about 40% of relative activity (4 °C, 30 days) and more than 50% of relative activity at pH 2.0-6.0. In addition, the laccase@CKMB indicated the reusability up to 6 reaction cycles while retaining 45.1% of relative activity. Moreover, the thermal deactivation kinetic studies of laccase@CKMB showed a lower k value (0.00275 min- 1) and higher t1/2 values (252.0 min) than the k value (0.00573 min- 1) and t1/2 values (121.0 min) of free laccase. CONCLUSIONS: We explored scientific and reasonable immobilization conditions of laccase@CKMB, and the laccase@CKMB possessed relatively better stabilities, which gave the immobilization of laccase on this cheap and easily available carrier material the possibility of industrial applications.