Micelle Surface Research Articles

Evaluation of mixed micellization behavior of imipramine hydrochloride drug and an ionic liquid mixture using different techniques: Effect of urea solutions

Micellization and interfacial behaviors of an ionic liquid 1-hexadecyl-3-methylimidazolium chloride (HMICL-16) mixed with a drug imipramine hydrochloride (IMH) were investigated in aqueous and aquo-urea (250 and 500 mmol kg−1) solutions using tensiometry as a probe. The drastic decline in the critical micelle concentration (cmc) of the mixed system confirms strong interaction supported by the energetic parameters in the mixed micelle and mixed surface in aqueous and aquo-urea media. Density Functional Theory (DFT) has been employed for the optimization of the geometrical structures of the ionic liquid and the drug moieties as well as of their coordinated structures to quantify the interactions in the mixed system through the Frontier Molecular Orbital (FMO) approach. Urea remarkably influences hydrogen bonding conformation of the hydrophobic region by changing the dielectric constant of water. As compared to aqueous system, non-ideality in IMH + HMICL-16 in aquo-urea solvent (250 mmol kg−1) was found to be reduced and the extent of nonideality further decreases with increase in [urea] to 500 mmol kg−1. Using surface tension method different physio-chemical parameters (interaction parameter, composition of components, activity coefficient, thermodynamic parameters, etc.) have been determined and interpreted. Both micellization and adsorption of IHM are found to be spontaneous in all the media investigated as indicated by the negative values of the free energies of micellization (−17.82, −17.66, and −17.57 kJ mol−1 respectively in water, 250 mmol kg−1 urea, and 500 mmol kg−1 urea), and the free energies of adsorption (−40.06, −39.30, and −32.92 kJ mol−1 respectively in these media). The addition of HMICL-16 to IMH causes an increased spontaneity of both the micellization and adsorption processes. FTIR and UV–visible spectral techniques were employed to assess the interactions amongst IMH and HMICL-16. UV–visible study of IMH shows maximum absorption at a wavelength of 249 nm due to a π-π∗ transition which underwent a hyperchromic shift upon interaction with HMICL-16. A quantitative estimation based on the Benesi-Hildebrand equation demonstrates negative values of free energy (ΔG) confirming the formation of energetically favorable complex in the investigated systems.

Synthesis of short-chain fluorocarbon surfactant: Enhancing surface and foam performance through hydrocarbon surfactants compounding

The research of short-chain fluorocarbon surfactants is crucial in effectively and environmentally extinguishing petrochemical fires. In this study, a short-chain fluorocarbon surfactant named 2H,2H-perfluorooctanoic acid sodium salt (PFH-CA) was synthesized, and then characterized its chemical structure, thermal stability, surface activity, and foam property. Subsequently, PFH-CA was compounded with hydrocarbon surfactants including sodium dodecyl sulfate (SDS), dodecyl trimethyl ammonium chloride (DTAC), and N,N-dimethyldodecylamine-N-oxid (OB-2) at different molar ratios. The surface tension, interaction parameters, and foam property of the PFH-CA/hydrocarbon surfactant compounding systems were investigated. The analysis indicates that PFH-CA exhibits excellent surface activity and thermal stability concomitant with poor foam property. Introducing SDS, DTAC, and OB-2 enhances the foam performance and reduces the consumption of PFH-CA through synergistic interactions. Especially, PFH-CA/DTAC (1:4) system possesses the strongest interactions and the best performance, with critical micelle concentration (CMC) and surface tension at CMC (γCMC) of 0.11 mmol/L and 20.90 mN/m, respectively. When concentration of PFH-CA exceeds 0.5 mmol/L, the foaming ability and foam stability stabilize at 30 cm and 90 %, respectively. The enhanced performance of PFH-CA/DTAC system is attributed to the electrostatic attraction between anionic and cationic surfactants, which facilitates the formation of micelles, subsequently leading to better surface activity and foam properties.

Impact of cold plasma-assisted Non-thermal deamidation and glycosylation on the construction of sugar derivative-zein conjugates for enhancing pickering foam stability: Technical principles and molecular interactions

There is an urgent need for stable, plant-based Pickering foams to address the growing consumer demand for sustainable, low-calorie, aerated sweet foods. This study employed a cold plasma-assisted deamidation and glycosylation (CPDG) approach to promote hydrophilic reassembly of zein, resulting in the formation of sugar derivative-zein conjugates. This was accomplished by coupling deamidated zein with polyhydroxy sugars including sucralose (Suc), maltitol (Mal), mannitol (Man), and stevioside (Ste). The research focused on elucidating the technical mechanisms of conjugate formation and the molecular interactions that enhance foam performance. The CPDG-treated conjugates demonstrated substantially increased foamability (140.00–223.33 %) and foam stability (28.57–105.07 %). Furthermore, microscopy (100 × magnification) revealed enhanced bubble counts (+13–15 bubbles) and interface layer thickness (+1.85–4.60 nm), along with a decrease in the drainage area (+8.47–20.52 %) for all conjugates, except Suc/ZN-CP. Particularly, the amphiphilic nature of Ste, characterized by multiple chiral centers, various hydroxyl groups, and a distinct carbonyl group, resulted in the highest covalent grafting degree (38.82 %), water solubility (0.28 mg/mL), foaming capacity (223.33 %), and foam stability (105.07 %) of ZN/Ste-CP after CPDG treatment. Regarding interaction forces, CPDG treatment enhanced both hydrogen bonding and covalent interactions in zein while diminishing electrostatic and hydrophobic forces. Confocal laser scanning microscopy validated that these changes resulted in a hydrophilic conformational shift of the conjugates, allowing Ste to coat micelle surfaces and form chain-like aggregates through viscous stretching, thereby facilitating favorable adsorption and unfolding at the air/water interface. The CPDG technology proved to be an effective and eco-friendly method for modifying the interface of zein, offering a valuable strategy for its application in highly flexible, stabilized Pickering foamed foods.

Highly Sensitive Electrochemiluminescence Biosensing Method for SARS-CoV-2 N Protein Incorporating the Micelle Probes of Quantum Dots and Dibenzoyl Peroxide Using the Screen-Printed Carbon Electrode Modified with a Carboxyl-Functionalized Graphene.

Obtaining stable electrochemiluminescence (ECL) emissions from a hydrophobic luminophore in aqueous solutions and designing a method without the use of an exogenous coreactant are promising for ECL biosensing. Here, a highly sensitive signal-on ECL immunoassay for the SARS-CoV-2 N protein was developed using micelles as an ECL tag. The micelles were prepared by coencapsulating the luminophore hydrophobic CdSe/ZnS quantum dots and coreactant dibenzoyl peroxide within the hydrophobic core of micelles. The ECL probe was obtained by covalently bonding a SARS-CoV-2 N protein-binding aptamer onto the micelle surface. The construction of the immunosensor was initiated by the immobilization of the anti-SARS-CoV-2 N protein antibody onto the screen-printed carbon electrode (SPCE) with a -COOH-functionalized surface. The surface functionalization of SPCEs was achieved through paste-exfoliated graphene, which was modified with a -COOH group through supramolecular-covalent scaffolds on SPCE. Upon achieving sandwich complexes on the immunosensor, an efficient ECL signal response at -1.4 V versus Ag/AgCl was obtained in phosphate buffer solution. The ECL assay was used for the sensitive determination of SARS-CoV-2 N protein with the linear range from 0.01 to 50 ng mL-1, and the detection limit was 3.0 pg mL-1. The immunosensor showed good reproducibility and stability, and the ECL immunoassay was used to determine the SARS-CoV-2 N protein in serum samples. The proposed approach to obtain micelles is versatile for the preparation of stable ECL luminophores by using hydrophobic materials, and the strategy provides an alternative for ECL bioassays based on the coreactant route.

SDBS-AEO Mixture for Triton X-100 Replacement: Surface Activity and Application in Biosensors.

Triton X-100 (TX-100) is a commonly used surfactant in the manufacture of biosensors. The factors limiting the use of TX-100 in biosensors are environmental concerns. In this study, the binary system of sodium dodecyl benzene sulfonate (SDBS) and fatty alcohol-polyoxyethlene ether (AEO) was investigated from the physicochemical principle of surfactant interaction and its application in biosensors. The results demonstrated that a mixture of SDBS and AEO at an appropriate molar ratio had a comparable activity to TX-100 in terms of surface activity, micelle formation, dynamic adsorption, foaming, emulsifying, and cell permeability. Theory and experimentation support the idea that SDBS-AEO might take the place of TX-100 in the manufacturing of biosensors. This study contributes to the development of alternatives to TX-100 and provides a new perspective for an in-depth study of the interaction mechanism of additives in biosensor design.

Dilatational rheological studies on the surface micelles of Poly(styrene)-[formula omitted]-Poly(4-vinyl pyridine) block copolymer at the air-water interface

A thin film of an amphiphilic block copolymer, poly(styrene)-b-poly(4-vinyl pyridine), is investigated at the air–water interface. The surface pressure - area per molecule isotherm and the static compressional modulus provide evidence of two phases, assigned as L1 and L2, respectively. The surface topography and the phase images of these phases obtained using atomic force microscope reveal the presence of surface micelles of different sizes and densities. The dilatational rheology of these phases was investigated using the oscillatory barrier method for different strain amplitudes (1−5%) and qualitatively assessed using Lissajous–Bowditch curves. It points out the emergence of nonlinearity (asymmetric shape and distorted ellipse) with an increase in strain amplitude. Using a fast Fourier transform, the amplitudes and the phases of different harmonics of the stress–strain curves were extracted, and the total harmonic distortion was determined. In contrast to L1 phase, the total harmonic distortion for the L2 phase increases monotonically with strain amplitude. Fixing the strain amplitude at 1% (small amplitude regime), the temperature as well as frequency dependence studies of the dilatational moduli were carried out. The dynamic storage moduli of the L1 phase is found to be insensitive to temperature while it decreases for the L2 phase suggesting softening. Further, evidence for solid-like viscoelastic response emerges (explained using the Kelvin–Voigt model) for the L1 phase, whereas the L2 phase show a cross-over behaviour.

Determining the Role of Surfactant on the Cytosolic Delivery of DNA Cross-Linked Micelles.

Nucleic Acid Nanocapsules (NANs) are nucleic acid nanostructures that radially display oligonucleotides on the surface of cross-linked surfactant micelles. Their chemical makeup affords the stimuli-responsive release of therapeutically active DNA-surfactant conjugates into the cells. While NANs have so far demonstrated the effective cytosolic delivery of their nucleic acid cargo, as seen indirectly by their gene regulation capabilities, there remain gaps in the molecular understanding of how this process happens. Herein, we examine the enzymatic degradation of NANs and confirm the identity of the DNA-surfactant conjugates formed by using mass spectrometry (MS). With surface enhanced (resonance) Raman spectroscopy (SE(R)RS), we also provide evidence that the energy-independent translocation of such DNA-surfactant conjugates is contingent upon their release from the NAN structure, which, when intact, otherwise buries the hydrophobic surfactant tail in its interior. Such information suggests a critical role of the surfactant in the lipid disruption capability of the DNA surfactant conjugates generated from degradation of the NANs. Using NANs made with different tail lengths (C12 and C10), we show that this mechanism likely holds true despite significant differences in the physical properties (i.e., critical micelle concentration (CMC), surfactants per micelle, Nagg) of the resultant particles (C12 and C10 NANs). While the total cellular uptake efficiencies of C12 and C10 NANs are similar, there were differences observed in their cellular distribution and localized trafficking, even after ensuring that the total concentration of DNA was the same for both particles. Ultimately, C10 NANs appeared less diffuse within cells and colocalized less with lysosomes over time, achieving more significant knockdown of the target gene investigated, suggesting more effective endosomal escape. These differences indicate that the surfactant assembly and disassembly properties, including the number of surfactants per particle and the CMC can have important implications for the cellular delivery efficacy of DNA micelles and surfactant conjugates.

Intelligent micelles for on-demand drug delivery targeting extracellular matrix of pancreatic cancer

As a key pathological feature of pancreatic ductal adenocarcinoma(PDAC), the dense extracellular matrix(ECM) limits the penetration of chemotherapy drugs and is involved in the formation of immunosuppressive microenvironment. Meanwhile, clinical practice has shown that the treatment strategy for ECM should consider its restriction of tumor cell metastasis, and the need for in-depth chemotherapy without destroying ECM is proposed. STAT3 inhibitors have been reported to regulate tumor microenvironment including interrupt the form of ECM. Therefore, we designed and established a micelle system MP@HA with in vivo targeting and responsive drug release function co-loading gemcitabine monophosphate and STAT3 inhibitor silibinin. The hyaluronic acid on the surface of the micelle can bind specifically to the CD44 molecule on the surface of tumor cells and help micelles accumulate at the tumor site. The nitroimidazole used to modify the polymeric skeleton can make the micellar structure collapse in response to hypoxia reduction conditions in the tumor environment, and release silibinin to widely regulate STAT3 molecules in the PDAC microenvironment. The polymer fragment attached with gemcitabine monophosphate can penetrate deep into PDAC tumors due to its small size and positive charge exposed, achieving deep chemotherapy. This research indicates a promising micelle system meeting complicated demands proposed in PDAC treatment to improve antitumor efficacy.

Exploration of dynamic interaction between β-lactoglobulin and casein micelles during UHT milk process

The protein aggregation induced by UHT treatment shortens the shelf life of UHT milk. However, the mechanism of β-Lg induced casein micelle aggregation remains unclear. Herein, the dynamic interaction between β-Lg and casein micelles during UHT processing was investigated by experimental techniques and molecular dynamics simulations. Results showed that β-Lg decreased the stability of casein micelles, increased their size and zeta potential. Raman and FTIR spectra analysis suggested that hydrogen and disulfide bonds facilitated their interaction. Cryo-TEM showed that the formation of the casein micelle/β-Lg complex involved rigid binding, flexible linking, and severe cross-linking aggregation during UHT processing. SAXS and MST demonstrated β-Lg bound to κ-casein on micelle surfaces with a dissociation constant (Kd) of 3.84 ± 1.14 μm. Molecular docking and dynamic simulations identified the interacting amino acid residues and clarified that electrostatic and van der Waals forces drove the interaction. UHT treatment increased hydrogen bonds and decreased total binding energy. The non-covalent binding promoted the formation of disulfide bonds between β-Lg and casein micelles under heat treatment. Ultimately, it was concluded that non-covalent interaction and disulfide bonding resulted in casein micelle/β-Lg aggregates. These findings provided scientific insights into protein aggregation in UHT milk.

Dual function surfactants for pharmaceutical formulations: The case of surface active and antibacterial 1-tolyl alkyl biguanide derivatives

One interesting field of research in the view of developing novel surfactants for pharmaceutical and cosmetic applications is the design of amphiphiles showing further bioactive properties in addition to those commonly displayed by surface-active compounds. We propose here the chemical synthesis, and characterization of 1-o-tolyl alkyl biguanide derivatives, having different lengths of the hydrocarbon chain (C3, C6, and C10), and showing surface active and antibacterial/disinfectant activities toward both Gram-positive and Gram-negative bacteria. Both surface active properties in terms of critical micelle concentration (CMC) and surface tension at CMC (γCMC), as well as the antimicrobial activity in terms of minimum inhibitory concentrations (MICs), were strongly dependent on the length of the hydrocarbon chain. Particularly, the C6 and C10 derivatives have a good ability to decrease surface tension (γCMC <40 mN/m) at low concentrations (CMC < 12 mM) and a satisfactory antibacterial effect (MIC values between 0.230 and 0.012 mM against S. aureus strains and between 0.910 and 0.190 against P.aeruginosa strains). Interestingly, these compounds showed a disinfectant activity at the tested concentrations that was comparable to that of the reference compound chlorhexidine digluconate. All these results support the possible use of these amphiphilic compounds as antibacterial agents and disinfectants in pharmaceutical or cosmetic formulations.

Studies on the properties and molecular dynamics simulations of nonionic surfactants based on succinic acid derivatives

AbstractNonionic surfactants have proven useful in various applications such as wastewater treatment, enhanced oil recovery, dyeing, and cosmetics. Novel nonionic surfactants such as PEMP, BEMP, HEMP and BEEP were synthesized based on succinic acid derivatives and using L‐isoleucine as the linking group and four polyether alcohols as the hydrophilic group. First, the structures of the four nonionic surfactants were studied using Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectra. Then the critical micelle concentration (CMC) and surface tension at CMC (γCMC) of the four nonionic surfactants in aqueous solution were tested. γ‐lg c curves determined the relationships of their surface properties as BEEP &gt; PEMP &gt; BEMP &gt; HEMP. In order to expand the range of applications for nonionic surfactants, we evaluated the salt‐resistant properties of four such surfactants. Our findings demonstrated that this class of surfactants indeed has superior salt‐resistant properties. Molecular dynamics (MD) simulations were used to study how surfactant molecules aggregate in the interfacial film. The study investigated the trend of solvent accessible surface area (SASA) over time. Results showed that the surfactant molecules interacted well with solvent molecules in the equilibrium state. This study investigates the performance differences among four types of surfactants using the electrostatic potential (ESP) distribution of their molecules. The study employed both experimental and computational simulations to provide a more comprehensive understanding of surfactant properties. The results offer insights into the theoretical research and application extension of this class of surfactants.

Aptamer biorecognition and gold nanoshell-mediated fluorescence quenching for glycoprotein analysis and breast cancer diagnosis

In recent years, glycoproteins have gained increasing attention due to their pivotal roles in cellular chemistry and signal transduction. However, the limited availability of rapid and wash-free analytical tools has impeded their utilization as circulating biomarkers for disease diagnosis in clinical settings. To address this challenge, we developed a gold nanoshell-mediated method for analyzing glycoprotein composition directly in native biofluids. Initially, glycoproteins are captured at the micelle surface through aptamer-protein interactions and were labeled with fluorescent lectin. Subsequently, the fluorescence of the lectin is locally quenched by the in-situ formation of gold nanoshell on micelle surface, while free-floating lectin remains unresponsive throughout this process. After optimizing the HAuCl4 dosage for gold nanoshell formation, we achieved rapid and strong fluorescence quenching against fluorescent lectin captured at micelle surface. Using this method, we analyzed the glycan compositions of CEA, HER2 and MUC1 with fluorescent ConA, Jacalin, LCA and PHA. The analyzing results demonstrated that our method can discriminate between glycoprotein compositions of plasma samples obtained from breast cancer patients and those from healthy donors.

Oxygen Self-Supplied Perfluorocarbon-Modified Micelles for Enhanced Cancer Photodynamic Therapy and Ferroptosis.

Photodynamic therapy (PDT) and ferroptosis show significant potential in tumor treatment. However, their therapeutic efficacy is often hindered by the oxygen-deficient tumor microenvironment and the challenges associated with efficient intracellular drug delivery into tumor cells. Toward this end, this work synthesized perfluorocarbon (PFC)-modified Pluronic F127 (PFC-F127), and then exploits it as a carrier for codelivery of photosensitizer Chlorin e6 (Ce6) and the ferroptosis promoter sorafenib (Sor), yielding an oxygen self-supplying nanoplatform denoted as Ce6-Sor@PFC-F127. The PFCs on the surface of the micelle play a crucial role in efficiently solubilizing and delivering oxygen as well as increasing the hydrophobicity of the micelle surface, giving rise to enhanced endocytosis by cancer cells. The incorporation of an oxygen-carrying moiety into the micelles enhances the therapeutic impact of PDT and ferroptosis, leading to amplified endocytosis and cytotoxicity of tumor cells. Hypotonic saline technology was developed to enhance the cargo encapsulation efficiency. Notably, in a murine tumor model, Ce6-Sor@PFC-F127 effectively inhibited tumor growth through the combined use of oxygen-enhanced PDT and ferroptosis. Taken together, this work underscores the promising potential of Ce6-Sor@PFC-F127 as a multifunctional therapeutic nanoplatform for the codelivery of multiple cargos such as oxygen, photosensitizers, and ferroptosis inducers.

Plasmonic Properties of Self-Assembled Gold Nanocrescents: Implications for Chemical Sensing.

A bottom-up approach, the Langmuir-Blodgett technique, is used for the preparation of composite thin films of gold nanoparticles and polymers: poly(styrene-b-2-vinylpyridine), poly-2-vinylpyridine, and polystyrene. The self-assembly of poly(styrene-b-2-vinylpyridine) at the air-water interface leads to the formation of surface micelles, which serve as a template for the organization of gold nanoparticles into ring assemblies. By using poly-2-vinylpyridine in conjunction with low surface pressure, the distance between nanostructures can be increased, allowing for optical characterization of single nanostructures. Once deposited on a solid substrate, the preorganized gold nanoparticles are subjected to further growth by the reduction of additional gold, leading to a variety of nanostructures which can be divided into two categories: nanocrescents and circular arrays of nanoparticles. The optical properties of individual structures are investigated by optical dark-field spectroscopy and numerical calculations. The plasmonic behavior of the nanostructures is elucidated through the correlation of optical properties with structural features and the identification of dominant plasmon modes. Being based on a self-assembly approach, the reported method allows for the formation of interesting plasmonic materials under ambient conditions, at a relatively large scale, and at low cost. These attributes, in addition to the resonances located in the near-infrared region of the spectrum, make nanocrescents candidates for biological and chemical sensing.

Effect of Electrostatic Interactions in Wormlike Micelles of Surfactants Based on Betaine and Charged Tertiary Amine with the Same Hydrophobic Groups

The viscoelastic properties and structure of solutions of mixed wormlike micelles based on a zwitterionic surfactant, oleylamidopropyldimethylcarboxybetaine (OAPB), and positively charged oleylamidopropyldimethylamine (OAPA) have been studied at different ratios between the components. At a small fraction of the cationic surfactant, OAPA, the solution exhibits viscoelastic properties characteristic of semidiluted solutions of entangled wormlike micelles, the presence of which has been confirmed by cryogenic electron microscopy data. It has been found that, as the molar fraction of the charged surfactant increases to 0.1, the viscosity and relaxation time of the solutions decrease by a factor of three, and the values of the storage modulus remain unchanged at short stress action times. The studied surfactants have a similar structure; therefore, when replacing zwitterionic OAPB molecules by positively charged OAPA molecules, the main factor of variations in the properties and structure is the enhancement of the electrostatic repulsion on the micelle surface. It has been shown that this factor leads to a decrease in the average length of micelles and an increase in their number, which have a weak effect on the rheological properties of the system as long as the length of the micelles is larger than the length of the subchains in the network. With an increase in the molar fraction of OAPA from 0.1 to 0.5, the viscosity and relaxation time drop drastically by several orders of magnitude and the viscoelastic response of the solution is lost; i.e., the network is destroyed. This transition from a semidilute solution to a dilute one is explained by a decrease in the length of the wormlike micelles and the formation of spherical ones. Cryogenic electron microscopy images have confirmed the formation of a mixture of long and short wormlike micelles with spherical micelles at an OAPA molar fraction of 0.5.

Role of cooperative effect by Mo and Pd mixed micellar assemblies for displaying the Pt/C like hydrogen evolution reaction

Cooperative effect as well as interfacial engineering are crucial factors for the development of electrochemical hydrogen evolution reaction (HER). Keeping this aspect in mind, a novel mixed micellar film using dodecylamine molybdenum (III) trichloride (MoDDA(I)) and dodecylamine palladium (II) dichloride (PdDDA(I)) was fabricated for electrochemical HER. The mixed micellar film was characterized by various instrumentation techniques to explore its structure and composition i.e. FESEM, AFM, FTIR. In addition, XPS was inserted to understand the underlying mechanism before and after electrolysis. The fabricated surface of mixed micelles was found to be hydrophobic. The efficiency of mix-metallomicelles as an electrocatalyst was checked in acidic media for electrochemical HER. The prepared reverse micellar film was activated by polarization cycles due to the in-situ reduction of metallic components. These metallic cores act as active centers for electrocatalytic HER. The HER activity of Mo-PdDDA(I) was found to be superior as compared with Pt/C. The prepared mixed micelles displayed 29.2 mV dec−1 Tafel slope. First, Mo and Pd based mixed micelles were prepared using a one-pot method. Benefiting from the role of organic media, MoDDA(I) and PdDDA(I) were able to orient in the form of reverse micelles. Wherein, Mo and Pd metal ions are present in the core of the micelles. The excellent activity exhibited by the formation of mix-metallomicelles, a synergic effect between metal ions, and interfacial engineering introduced by the surfactant moiety, which in turn facilitates the adsorption and activation of hydrogen ions on the electrode surface. Additionally, the mixed micelles provide a high surface area for the electrochemical reaction and enhance the conductivity of the electrode.

Ionic strength and anion‐specificity effects on the interfacial behavior of double hydrophilic block copolymer PNIPAM‐b‐POEGA

AbstractIn our prior paper, surface micelles with the core‐shell‐petal structure of the double hydrophilic block copolymer poly(N‐isopropylacrylamide)‐block‐poly[oligo(ethylene glycol) acrylate] (PNIPAM‐b‐POEGA) were successfully evaluated. In this work, ionic strength (under acidic conditions) and anion‐specificity effects (under neutral conditions) on the aggregation behavior of PNIPAM‐b‐POEGA at the air/water interface and the morphologies of its Langmuir–Blodgett (LB) films were systematically studied. Under acidic conditions, the salting‐out effect prevails over the electrostatic shielding effect, and the amide group shells with a slight protonation degree are covered up by the large POEGA petals. Under neutral conditions, the stretching degrees of POEGA blocks at low/moderate salt concentrations are close. At high salt concentrations, the isotherms gradually shift to large molecular areas in the order of the NaCl, Na2SO4, NaNO3, and NaSCN cases. The hysteresis degrees of the monolayers increase with the increase of salt concentrations due to the gradually increased interfacial stretching degree and compression‐induced underwater solubility of POEGA blocks. All the initial LB films of PNIPAM‐b‐POEGA exhibit isolated circular micelles with small cores. Upon compression, the LB films exhibit slightly large micelles because of the possible coalescence of some neighboring cores.

Counter-ion adsorption and electrostatic potential in sodium and choline dodecyl sulfate micelles - a molecular dynamics simulation study.

Choline-based surfactants are interesting both from the practical point of view to obtaining environmental-friendly surfactants as well as from the theoretical side since the interactions between the choline and surfactants can help to understand self-assembly phenomena in deep eutectic solvents. Although no significant change was noticed in the micelle size and shape due to the exchange of the sodium counter-ion by choline in our simulations, the adsorption of the choline cation over the micelle surface is stronger than the adsorption of the sodium, which leads to a reduction of the exposed surface area of the micelle and remarkable effects over the electrostatic potential. The choline neutralizes the surface charge of the surfactant better than sodium; however, this is partially compensated by a stronger water orientation around the SDS micelle. The balance between the contributions from the surfactant, the counter-ion, and water to the electrostatic potential leads to a complex pattern with alternate regions of positive and negative potential at the micelle/water interface which can be important to the incorporation of other charged species at the micelle surface as well as for the interaction between micelles in solution. To evaluate the effects of the counter-ion substitution, micelles of sodium dodecyl sulfate (SDS) and choline dodecyl sulfate (ChDS) were studied and compared by means of molecular dynamics simulations in aqueous solution. In both cases, the simulations started from pre-assembled micelles with 60 dodecyl sulfate ions and 240-ns simulations were performed at NPT ensemble at T = 323.15K and P = 1bar using the Gromacs software with the OPLS-AA force field to describe dodecyl sulfate and choline, Åqvist parameters for sodium, and SPC model for water molecules.

Constructing a Comprehensive Nanopattern Library through Morphological Transitions of Block Copolymer Surface Micelles via Direct Solvent Immersion.

This study establishes a comprehensive library of nanopatterns achievable by a single block copolymer (BCP), ranging from spheres to complex structures like split micelles, flower-like clusters, toroids, disordered micelle arrays, and unspecified unique shapes. The ordinary nanostructures of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) surface micelles deposited on a SiOx surface undergo a unique morphology transformation when immersed directly in solvents. Investigating parameters such as immersion solvents, BCP molecular weight, substrate interactions, and temperature, this work reveals the influence of these parameters on the thermodynamics and kinetics governing the morphology transformation. Additionally, the practical application of BCP nanopattern templates for fabricating metal nanostructures through direct solvent immersion of surface micelles is demonstrated. This approach offers an efficient and effective method for producing diverse nanostructures, with the potential to be employed in nanolithography, catalysts, electronics, membranes, plasmonics, and photonics.

Single-Nucleotide-Specific Lipidic Nanoflares for Precise and Visible Detection of KRAS Mutations via Toehold-Initiated Self-Priming DNA Polymerization.

Accurate identification of single-nucleotide mutations in circulating tumor DNA (ctDNA) is critical for cancer surveillance and cell biology research. However, achieving precise and sensitive detection of ctDNAs in complex physiological environments remains challenging due to their low expression and interference from numerous homologous species. This study introduces single-nucleotide-specific lipidic nanoflares designed for the precise and visible detection of ctDNA via toehold-initiated self-priming DNA polymerization (TPP). This system can be assembled from only a single cholesterol-conjugated multifunctional molecular beacon (MMB) via hydrophobicity-mediated aggregation. This results in a compact, high-density, and nick-hidden arrangement of MMBs on the surface of lipidic micelles, thereby enhancing their biostability and localized concentrations. The assay commences with the binding of frequently mutated regions of ctDNA to the MMB toehold domain. This domain is the proximal holding point for initiating the TPP-based strand-displacement reaction, which is the key step in enabling the discrimination of single-base mutations. We successfully detected a single-base mutation in ctDNA (KRAS G12D) in its wild-type gene (KRAS WT), which is one of the most frequently mutated ctDNAs. Notably, coexisting homologous species did not interfere with signal transduction, and small differences in these variations can be visualized by fluorescence imaging. The limit of detection was as low as 10 amol, with the system functioning well in physiological media. In particular, this system allowed us to resolve genetic mutations in the KRAS gene in colorectal cancer, suggesting its high potential in clinical diagnosis and personalized medicine.