Lower CMC Values Research Articles

Amphiphilic pyrene-functionalized triazoliums for ATP recognition

Four pyrene functionalized triazolium salts with different lengths of alkyl tail from C4 to C16, i.e., PYTAZ-C4, PYTAZ-C8, PYTAZ-C12 and PYTAZ-C16, have been designed and synthesized for ATP recognition. It was revealed that the longer alkyl tail anchored receptors PYTAZ-C12 and PYTAZ-C16 exhibit low CMC values, and self-assemble nanoaggregation at low concentration in aqueous solution, which show a pyrene-based excimer emission at 496 nm. However, the shorter alkyl anchored receptors PYTAZ-C4 and PYTAZ-C8 give only the pyrene-based monomer emission at 380 nm at the test concentration of 10 μM in aqueous solution. Importantly, PYTAZ-C12 and PYTAZ-C16 exhibit a good fluorescence turn-on response toward polyphosphate anions, especially ATP, with the detection limits of 2.5 μM and 0.77 μM, respectively. Furthermore, probe PYTAZ-C16 was successfully used for fluorescence imaging of intracellular ATP in living cells.

Wettability of a Polymethylmethacrylate Surface by Fluorocarbon Surfactant Solutions

To clarify the adsorption behavior of fluorocarbon surfactants on PMMA surfaces, the contact angles of two nonionic fluorocarbon surfactants (FNS-1 and FNS-2) and an anionic fluorocarbon surfactant (FAS) on polymethylmethacrylate (PMMA) surface were determined using the sessile drop method. Moreover, the effects of molecular structures on the surface tension, adhesion tension, solid–liquid interfacial tension, and adhesion work of the three fluorocarbon surfactants were investigated. The results demonstrate that the adsorption amounts for three fluorocarbon surfactants at the air–water interface are 4~5 times higher than those at the PMMA–solution interface. The three fluorocarbon surfactants adsorb on the PMMA surface by polar groups before CMC and by hydrophobic chains after CMC. Before CMC, FNS-2 with the smallest molecular size owns the highest adsorption amount, while FAS with large-branched chains and electrostatic repulsion has the smallest adsorption amount. After CMC, the three fluorocarbon surfactants form aggregates at the PMMA-liquid interface. FAS possesses the smallest adsorption amount after CMC. Besides, FNS-1 possesses a higher adsorption amount than FNS-2 due to the longer fluorocarbon chain and the lower CMC value of FNS-1. The adsorption behaviors of nonionic and anionic fluorocarbon surfactants on the PMMA surface are different. FAS forms interfacial aggregates before CMC, which may be attributed to the electrostatic interaction between the anionic head of FAS and the PMMA surface.

Cationic Gemini surfactants: a review on synthesis and their applications

Abstract The molecules of Gemini surfactants are dimeric and consist of two monomeric surfactant units linked by a spacer. Among them, cationic Gemini surfactants have a wide range of application in various industrial sectors such as pharmaceuticals, home and personal care, corrosion inhibition, etc. Various methods of synthesis have been investigated and tested for the synthesis of cationic Gemini surfactants. The surface properties of Gemini surfactants are highly dependent on various factors like spacer, headgroups, counterions, etc. The cationic Gemini surfactants have lower CMC values as compared to their monomeric analogues. This review highlights the different methods for the synthesis of cationic Gemini surfactants and the applications of these surfactants in different fields are presented.

New piperidinium surfactants with carbamate fragments as effective adjuvants in insecticide compositions based on imidacloprid.

Surfactants, particularly non-ionic ones, are widely used as adjuvants in pesticide formulations due to their ability to maintain pesticide effectiveness without changing solution properties, such as pH. While non-ionic surfactants are generally low-toxic, stable, and excellent dispersants with high solubilization capabilities, they may be less effective than cationic surfactants, which offer superior surface activity, transport properties, and antimicrobial action. This study investigates the efficacy of new piperidinium surfactants with carbamate fragments as adjuvants in insecticide formulations containing imidacloprid. The efficacy of these formulations is being assessed against greenhouse whitefly, a pest known to harm cultivated and ornamental flowering plants. The aggregation behavior of piperidinium surfactants containing carbamate fragments was investigated, and their wetting effect was evaluated. Synthesized surfactants have lower CMC values compared to their methylpiperidinium analogue. The effect of piperidinium surfactants on the insecticide concentration on the surface and inside tomato leaves was assessed using spectrophotometric methods. It was found that the introduction of piperidinium surfactants with carbamate fragment at a concentration of 0.1% wt. allows for decrease in lethal concentration of imidacloprid up to 10 times, thereby testifying the marked increase in the effectiveness of imidacloprid against the greenhouse whitefly insect pest (Trialeurodes vaporariorum). It was shown that the main factors responsible for the enhanced efficacy of the insecticide were the ability of the surfactant to increase the concentration of imidacloprid on the leaf surfaces and improve their penetration into the plant. The presented work employed a comprehensive approach, which significantly increases the generalizability of the results obtained and provides the ability to predict the effect and target selection of adjuvants. © 2024 Society of Chemical Industry.

Synthesis of Amphiphilic Block Copolymer and Its Application in Pigment-Based Ink.

Amphiphilic block copolymers-based aqueous color inks show great potential in the field of visual communication design. However, the conventional step-by-step chemistry employed to synthesize the amphiphilic block copolymers is intricate, with low yield and high economic and environmental costs. In this work, we present a novel method for preparing an amphiphilic AB di-block copolymer of PCL-b-PAA by employing a combined polymerization strategy that involves both cationic ring-opening polymerization (ROP) of the ε-caprolactone monomer and the reversible addition-fragmentation chain-transfer (RAFT) polymerization on the acrylic acid monomer simultaneously. The corresponding polycaprolactone (PCL) and polyacrylic acid (PAA) serve as the hydrophobic and hydrophilic units, respectively. The effectiveness of the amphiphilic AB di-block copolymer as the polymeric pigment dispersant for water-based color inks is evaluated. The amphiphilic AB di-block copolymer of PCL-b-PAA exhibits a molecular weight of 1400 g mol-1, which is consistent with the theoretical value and suitable for polymeric dispersant application. The high surface excess (Γmax) of the PCL-b-PAA in water indicates a densely packed molecular morphology at the water/air interface. Additionally, micelles can be stably formed in the aqueous PCL-b-PAA solution at very low concentrations by demonstrating a low CMC value of 10-4 wt% and a micelle dimension of approximately 30 nm. The model ink dispersion is prepared using organic dyes (Disperse Yellow 232) and the amphiphilic block copolymer of PCL-b-PAA. The dispersion demonstrates near-Newtonian behavior, which is highly favorable for the application as inkjet ink. Furthermore, the ink dispersion displays a low viscosity, making it particularly suitable for visual communication design and printing purposes. Moreover, the ink dispersion demonstrates an unimodal distribution of the particle size, with an average diameter of approximately 500 nm. It retains exceptional stability of dispersion and even conducts a thermal aging treatment at 60 °C for 5 days. This work presents a facile and efficient synthetic strategy and molecular design of AB di-block copolymer-based dispersants for dye dispersions.

Amphiphilic polylactic acid-b-poly(N-(3-aminopropyl) methacrylamide) copolymers: Self-assembly to polymeric micelles for gene delivery

In this study, for the first time diblock copolymers of PLA-b-PAPMA with three different sizes were synthesized in order to fabricate cationic micelles. In this copolymer, p(APMA) block with hydrophilic cationic nature could serve as a nucleic acid condensation platform as well as the shell of micellar structure in the self-assembly process. The p(APMA) block was electrostatically complexed with nucleic acid, and formed a neutral or mildly positive charge micellar surface, thus providing the nanoparticles safety and stability. On the other hand, polylactic acid as a hydrophobic polymer in diblock copolymer structure formed core of micelles which could encapsulate hydrophobic therapeutics. The synthesized copolymers, PLA74-b-PAPMA14, PLA121-b-PAPMA22, PLA121-b-PAPMA103 were evaluated in terms of self-assembly capability, size, polydispersity index, plasmid condensation, transfection efficacy and cytotoxicity against C26 cells. Obtained results demonstrated low CMC values for all copolymers. PLA121-b-PAPMA103 diblock copolymer condensed green fluorescent protein plasmid at C/P 1 and higher, while other diblock copolymers were able to condense plasmid above C/P 70. The self-assembly structures of cationic micelles before and after plasmid condensation showed spherical morphology in SEM analysis while DLS data illustrated appropriate size (161.7 ± 8) and PDI (0.276) for PLA121-b-PAPMA103 diblock copolymer. It could be concluded that the cationic micelles with approximately the molecular weight ratio of hydrophilic block to total polymer mass of 60 % and larger than 50 % provided higher stability, condensation ability and transfection efficiency which could be attributed to the better self-assembly process and better amine groups exposure on the micellar surface.

Exploring the interactions of anionic dye tartrazine with cationic surfactants in aqueous solution: Insights into micellization and interfacial properties

Different techniques such as conductometric, tensiometric and spectroscopic methods were deployed to investigate the interactions of tartrazine (TZ) dye with cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPB) in aqueous media at four temperatures. Results revealed a lower cmc values for CPB as compared to CTAB in presence/or absence of aqueous TZ solutions. A qualitative analysis, using UV–vis spectroscopy, was carried out to understand the interactions between the dye TZ and CTAB/CPB in the premicellar and post micellar phase. Interfacial properties such as surface excess concentration (Γmax), area occupied per surfactant molecule (Amin), surface pressure (πcmc), standard Gibbs energy of adsorption (ΔGado), packing parameter (P), etc., were evaluated at air–water/aqueous TZ solution of CTAB/CPB. The equilibrium model was used to determine the change in standard Gibbs energy (ΔGm0), enthalpy (ΔHm0), and entropy (ΔSm0) of micellization. Due to the interruption of the structured water molecules encasing the hydrophobic groups of the surfactant, the critical micelle concentration (cmc) rose with temperature. For both the studied systems, the values of ΔGm0 and ΔHm0 were negative, implying that the process of micellization is thermodynamically spontaneous and exothermic. The -TΔSm0 values, which were found to be greater than ΔHm0 values, suggest the gain in entropy primarily governs the process of micellization.

Biodegradable amidequats, derivatives of caprylic and pelargonic acids as cationic surfactants for agricultural applications

In this study, we proposed to incorporate natural herbicides i.e. caprylic and pelargonic acids into an amide functional group of a cationic surfactant, thus obtaining amidequats. All the obtained amidequats can be classified as ionic liquids since their melting point values were below 100 °C. Moreover, all compounds were stable up to 166 °C. The obtained ionic liquids exhibited high surface activity, as confirmed by their low CMC values (ranging from 0.02 to 4.32 mmol·L−1) as well as their ability to efficiently lower the surface tension (to 23.8–30.2 mN·m−1). The amidequats, derivatives of caprylic and pelargonic acid exhibited different foam formation ability and its stability depending on their structure. Subsequent tests indicated that amidequats comprising the decyl and dodecyl substituents were readily biodegradable (mineralization at 63–78 % within 10 days). They did not significantly affect the germination of the model monocotyledon plant (sorghum) up to 500 mg·L−1, however, they showed phytotoxicity in relation to the model dicotyledon weed (common sunflower) and displayed low or moderate toxicity towards model microorganisms commonly found in soil, which confirms their low environmental impact.

Micellization of phenothiazine drug and nonionic surfactant TX-165 mixture in different composition and media: surface tension and UV-visible study

ABSTRACT Micelles serve as a replica for the investigation of bio-membranes as physicochemical association of drugs with micelles is envisioned as their interconnection with bio-membranes. Micellization properties of promethazine hydrochloride (PMT) with TX-165 (a nonionic surfactant) in aqueous, 50 mmolkg−1 NaCl and 500 mmolkg−1 urea solutions were analysed in detail using surface tension measuring tool. PMT is employed as an analgesic, anticholinergic, sedative, antihistaminic as well as antipsychotic drug. UV-visible spectroscopy is also utilised to evaluate PMT-TX-165 interactions in an aqueous solution. Pure constituent and their mixtures (PMT + TX-165) of each composition showed lower cmc value in NaCl than in the aqueous system, while urea-containing solutions showed higher cmc value. Increasing the mole fraction (α 1) of TX-165 in mixed systems increases the interaction between the employed constituents (PMT and TX-165). The evaluated Gibbs free energy values of singular, and mixed system in each media were attained negative that uncovering that each system depicted the spontaneity of micellization. Various thermodynamic parameters were examined and discussed thoroughly. A UV-visible measurement also confirms that the components interact in treaty with surface tension measurements. Based on the results of this study, TX-165 was designed in a forthright manner, which could be an efficient drug delivery vehicle for phenothiazine drugs.

Synthesis and Characterization of Imidazole Based Cationic Surfactants as Disinfectants

Citric acid-based cationic surfactants using 1-methyl imidazolium as coordinizing agent has been synthesized and characterized. The cationic surfactants is produced in excellent yields (70%) and has been examined by TGA, FTIR, 1H NMR and are found to have good surface-active properties. FTIR analysis showed the presence of ester confirmed by 1H NMR (the chemical shift value of 3.7 ppm and 3.8 ppm is due to the presence of an ester) in the surfactant. The biodegradability confirmed by BOD analysis. It is found that cationic imidazolium surfactants having surface tenstion of (12 mN/m) with chloride as a counter ion. The results show that cationic imidazolium surfactants with longer hydrophobic chains have a lower CMC value. TGA result shows good thermal properties of cationic surfactant. Invitro study of cationic surfactant over fungal cell indicates its antifungal activity (70% inhibition at 350 ppm) and its appliaction as disinfactant.

Thermo/pH dual-responsive micelles based on the host\u2013guest interaction between benzimidazole-terminated graft copolymer and \u03b2-cyclodextrin-functionalized star block copolymer for smart drug delivery

Novel temperature and pH dual-sensitive amphiphilic micelles were fabricated exploiting the host–guest interaction between benzimidazole-terminated PHEMA-g-(PCL-BM) and β-CD-star-PMAA-b-PNIPAM. The fabricated graft copolymer had a brush-like structure with star side chains. The micelles were utilized as dual-responsive nanocarriers and showed the LCST between 40 and 41 °C. The acidic pH promoted the dissociation of the PHEMA-g-(PCL-BM: β-CD-star-PMAA-b-PNIPAM) micelles. DOX.HCl was loaded into the core of the micelles during self-assembly in an aqueous solution with a high encapsulation efficacy (97.3%). The average size of the amphiphilic micelles was about 80 nm, suitable size for the enhanced permeability and retention effect in tumor vasculature. In an aqueous environment, these micelles exhibited very good self-assembly ability, low CMC value, rapid pH- and thermo-responsiveness, optimal drug loading capacity, and effective release of the drug. The biocompatibility was confirmed by the viability assessment of human breast cancer cell line (MCF-7) through methyl tetrazolium assay. DOX-loaded micelles displayed excellent anti-cancer activity performance in comparison with free DOX.Graphical

Synthesis, micellization and cytotoxic studies of ester‐functionalized imidazolium gemini surfactants

AbstractThe fatty acid‐based imidazolium gemini surfactants containing hydroxy‐substituted spacers were synthesized and characterized by different spectral techniques. The micellization behavior of product compounds was studied by determining their critical micelle concentration (cmc) values from steady state fluorescence and conductivity measurements. The thermodynamic parameters of micellization of synthesized gemini surfactants confirmed that the micelle formation is a thermodynamically favorable, endothermic and an entropy driven phenomenon. The surfactants were further analyzed for their cytotoxic nature by treating them upon human embryonic kidney cell (HEK‐293) line and were found to be significantly low cytotoxic. The interesting features like low cmc values, non‐cytotoxic and eco‐friendly nature of the gemini surfactants may offer new and more efficient substitutes to the conventional drug delivery systems. Thus the gemini surfactants may serve as promising candidates in the biomedical and pharmaceutical fields.

Example of removing printing ink from plastic surface using quaternary ammonium-modified waste cooking oil

ABSTRACT The printing ink on the plastic surface greatly reduces the quality of recycled plastic products. In this work, quaternary ammonium-modified waste cooking oil (WCOQE) was fabricated, using waste cooking oil, epichlorohydrin and trimethylamine aqueous solution as raw materials, by ring-opening esterification and quaternary amination reaction. The synthesis conditions of WCOQE were optimized, and the structure and properties of WCOQE were characterized by FTIR, zeta potential and 1H NMR. Furthermore, WCOQE had excellent emulsifying performance, low kraft point, low CMC value, good foaming and stability, which could effectively reduce the surface tension of water, showing application potential in the field of plastic deinking. Importantly, compared with the waste cooking oil without deinking effect, the WCOQE had an excellent deinking performance on the ink on plastic surface, and the deinking efficiency could be improved by increasing the concentration of deinking agent, the deinking temperature, and prolonging the pre-soaking and stirring time. The results of AFM, EDS, optical photos and Leica microscope showed that the roughness changed significantly, and the ink molecules were gradually peeling off. This work highlighted the excellent potential of quaternary ammonium-modified waste cooking oil for the removal of printing inks on the plastic surface.

Highly Efficient Modular Construction of Functional Drug Delivery Platform Based on Amphiphilic Biodegradable Polymers via Click Chemistry.

Amphiphilic copolymers with pendant functional groups in polyester segments are widely used in nanomedicine. These enriched functionalities are designed to form covalent conjugates with payloads or provide additional stabilization effects for encapsulated drugs. A general method is successfully developed for the efficient preparation of functional biodegradable PEG-polyester copolymers via click chemistry. Firstly, in the presence of mPEG as initiator, Sn(Oct)2-catalyzed ring-opening polymerization of the α-alkynyl functionalized lactone with D,L-lactide or ε-caprolactone afforded linear mPEG-polyesters bearing multiple pendant alkynyl groups. Kinetic studies indicated the formation of random copolymers. Through copper-catalyzed azide-alkyne cycloaddition reaction, various small azido molecules with different functionalities to polyester segments are efficiently grafted. The molecular weights, polydispersities and grafting efficiencies of azido molecules of these copolymers were investigated by NMR and GPC. Secondly, it is demonstrated that the resulting amphiphilic functional copolymers with low CMC values could self-assemble to form nanoparticles in aqueous media. In addition, the in vitro degradation study and cytotoxicity assays indicated the excellent biodegradability and low cytotoxicity of these copolymers. This work provides a general approach toward the preparation of functional PEG-polyester copolymers in a quite efficient way, which may further facilitate the application of functional PEG-polyesters as drug delivery materials.

2-(2-Cholesteroxyethoxyl)ethyl 3′-S-glutathionylpropionate and its self-assembled micelles for brain delivery: Design, synthesis and evaluation

The blood–brain barrier (BBB) is a barrier that prevents almost all large and most small exogenous molecules from reaching the brain. The barrier is the major cause of treatment failure for most brain diseases. Extensive efforts have been made to facilitate drug molecules to cross the BBB. One of the approaches is to employ an endogenous ligand or ligand analogue that can enter the brain through its transporter or receptor at the BBB as a brain-targeting agent.Glutathione (GSH) transporters are richly expressed at the BBB with limited presence in other tissues except kidneys. 2-(2-Cholesteroxyethoxyl)ethyl 3′-S-glutathionylpropionate (COXP), formed by connecting GSH with cholesterol through a linker, was designed as a GSH transporter-mediated brain targeting molecule. The amphiphilic nature of COXP enables the molecule to self-assemble to form micelles with a CMC value of 3.9 μM. By using DiR as a fluorescence tracking agent and the whole-body fluorescence imaging technique, the brain distribution of DiR delivered by COXP micelles in mice was 20 folds higher when compared with free DiR. Interestingly, the brain targeting effect was further enhanced by co-administration of GSH. The low CMC value and effective brain targeting make COXP micelles a promising drug delivery system to the brain.

Synthesis, characterization, structural description, TGA, micellization behavior, DNA-binding and antioxidant activity of mono-, di- and tri-nuclear Cu(II) and Zn(II) carboxylate complexes

Mono-, di- and tri-nuclear Cu(II) and Zn(II) carboxylate complexes were synthesized and structurally characterized having general formulas [Cu2(biphenylacetate)4(DMSO)2] (1), [Zn(3,4-dichlororophenylacetate)2(1,10-phenanthroline)(H2O)] (2) and [Zn3(3,4-dichlororophenylacetate)6(2,2-bipyridine)2] (3). Complex 1 is a dinuclear Cu(II) complex with distorted square pyramidal geometry. Complex 2 is a mononuclear Zn(II) complex with distorted octahedral geometry while 3 is a tri-nuclear Zn(II) complex with octahedral (central Zn) as well as square pyramidal (terminal Zn) geometries. The stability of all complexes was checked by TGA and were found thermally stable. The solubility of the complexes was enhanced by using cationic (CTAB) and anionic (SDS) surfactants. Lower CMC values for SDS revealed good interaction as compared to CTAB. DNA-binding ability of the complexes was determined by UV–vis spectrophotometry and viscometry. All complexes bind with DNA effectively. The binding constant values from spectral analysis are 1.00(±0.02) × 104, 1.34(±0.01) × 105 M−1 and 1.11(±0.01) × 104 M−1 for 1–3, respectively. The DPPH-scavenging assay was performed by UV–vis spectrophotometry. All complexes showed good inhibition against the free radical. IC50 values for 1–3 are 109.98, 167.31 and 153.12 µM, respectively. The complexes were found to possess nice biological relevance.

Redox and pH dual sensitive folate-modified star-like amphiphilic copolymer based on castor oil for controlled doxorubicin delivery

To overcome the problems associated with the use of doxorubicin (DOX), such as low solubility, high toxicity, and side effects, a redox and pH-sensitive drug delivery system based on a star-like copolymer of folate-modified poly (ethylene glycol) (PEG) and biodegradable castor oil was developed. Redox-sensitive disulfide linkage and pH-sensitive imine linkage were incorporated in the backbone of the star-like copolymer, which self-assembled into stable micelles with small particle size (91.67 nm), narrow size distribution, and low CMC value (2.7 mg/L). The disassembly behaviors of the micelles when exposed to endolysosomal pH of 5.5 and a high concentration of GSH were evaluated by scanning electron microscope from the changes of micellar morphology.The micelles were used to load DOX into the hydrophobic core. Drug loading capacity (DLC) and drug loading efficiency (DLE) were calculated to be 15.93% and 96.13%, respectively. In vitro release studies showed that DOX release from micelles followed a redox and pH-triggered manner. The introduction of dual trigger further expedited DOX release.In vitro cytotoxicity of the copolymer against HDF cells was investigated. The star-like copolymer showed no toxicity. While the DOX-loaded micelles suggested enhanced cytotoxicity against HeLa cells. These results indicated that these redox and pH-sensitive micelles have the potential as a nanocarrier for DOX and other hydrophobic anti-cancer drugs.

Chemosensitizing micelles self-assembled from amphiphilic TPGS-indomethacin twin drug for significantly synergetic multidrug resistance reversal.

Vitamin E d-ɑ-tocopheryl poly(ethylene glycol) 1000 succinate (TPGS) and indomethacin (IDM) can reverse multidrug resistance (MDR) via inhibiting P-glycoprotein (P-gp) and multidrug resistance associated protein 1 (MRP1) respectively, but their drawbacks in physicochemical properties limit their clinical application. To overcome these defects and enhance MDR reversal, the amphiphilic TPGS-IDM twin drug was successfully synthesized via esterification, and could self-assemble into free and paclitaxel-loaded (PTX-loaded) micelles. The micelles exhibited lower CMC values (5.2 × 10-5 mg/mL), long-term stability in PBS (pH 7.4) for 7 days and SDS solution (5 mg/mL) for 3 days, and effective drug release at esterase/pH 5.0. Moreover, the micelles could down-regulate ATP levels and promote ROS production in MCF-7/ADR via the mitochondrial impairment, therefore achieving MDR reversal and cell apoptosis. Additionally, the PTX-loaded micelles could significantly inhibit the cell proliferation and promote apoptosis for MCF-7/ADR via the synergistic chemosensitizing effect of TPGS and IDM, and synergistic cytotoxic effect of TPGS and PTX. Thus, the chemosensitizing micelles self-assembled from amphiphilic TPGS-indomethacin twin drug have the great potentials for reversing MDR in clinical cancer therapy.

Investigation of micellar and interfacial phenomenon of amitriptyline hydrochloride with cationic ester-bonded gemini surfactant mixture in different solvent media.

Herein, the interaction among the antidepressant drug amitriptyline hydrochloride (AMT) and a green gemini surfactant, ethane-1, 2-diyl bis(N,N-dimethyl-N-tetradecylammoniumacetoxy) dichloride (14-E2-14), via numerous techniques such as tensiometry, fluorimetry, FT-IR and UV-visible spectroscopy in three different media (aqueous 0.050 mol·kg-1 NaCl, 0.50 and 1.0 mol·kg-1 urea) were investigated. AMT is used to treat mental illness or mood problems, such as depression. The aggregation of biologically active ingredients can enhance the bioavailability of hydrophobic drugs. A significant interaction between AMT and 14-E2-14 was detected by tensiometric study as the critical micelle concentration (cmc) of AMT+14-E2-14 is reduced upon an increase of mole fraction (α1) of 14-E2-14. The decrease in cmc indicates the nonideality of studied mixtures of different compositions. Although, employed drug AMT is freely soluble in the aqueous and non-aqueous system but is not hydrophobic enough to act as its carrier. Instead, gemini surfactant formed spherical micelles in an aqueous system and their high solubilization capability, as well as their relatively lower cmc value, makes them highly stable in vivo. The cmc values of AMT+14-E-14 mixtures in all cases were further decreased and increased in NaCl and urea solutions respectively as compared with the aqueous system. Numerous micellar, interfacial, and thermodynamic parameters have been measured by applying various theoretical models. The obtained changes in the physicochemical assets of AMT upon adding of 14-E2-14 are likely to enhance the industrial and pharmaceutical applications of gemini surfactants. The negative interaction parameters (βm and βσ), indicate synergistic attraction is occurring in the mixed systems. The aggregation number (Nagg), Stern–Volmer constant (Ksv), etc. are attained through the fluorescence method, also supporting the attractive interaction behavior of AMT+14-E2-14 mixtures in all solvents. The Nagg was found to increase in the salt solution and decrease in the urea system compared with the aqueous solution. FT-IR and UV-visible analysis also depict the interaction between the constituent alike tensiometry and fluorimetry methods. The results suggested that gemini surfactants may serve as a capable drug delivery agent for antidepressants, improving their bioavailability.

6-Aminocaproic acid as a linker to improve near-infrared fluorescence imaging and photothermal cancer therapy of PEGylated indocyanine green

Clinical extensive application of indocyanine green (ICG) is limited by several drawbacks such as poor bioenvironmental stability, aggregate propensity, and rapid elimination from the body, etc. In this study, we construct a novel amphiphilic mPEG-ACA-ICG conjugate by modifying synthetic heptamethine cyanine derivative ICG-COOH with a hydrophobic linker 6-aminocaproic acid (ACA) and amino-terminal poly(ethylene glycol) (mPEG-NH2). The as-prepared mPEG-ACA-ICG conjugate has the ability to self-assemble into micellar aggregates in an aqueous solution with a lower CMC value than mPEG-ICG conjugate without ACA linker. More importantly, compared with free ICG and mPEG-ICG conjugate, mPEG-ACA-ICG nanomicelles exhibited better stability and higher photothermal conversion efficiency upon near-infrared light irradiation due to the intramolecular introduction of a hydrophobic ACA segment. In our in vivo experiment, mPEG-ACA-ICG nanomicelles ensured the formidable effect on tumor photothermal therapy (PTT) and the maximum tumor inhibition rate reached 72.6 %. In addition, real-time determination ability for fluorescence image-guided surgery (FIGS) of mPEG-ACA-ICG nanomicelles was also confirmed on tumor xenograft mice model. Taken together, mPEG-ACA-ICG conjugate may hold great promise for non-invasive cancer theranostics.