Determination of the critical micelle concentration of surfactants using fluorescence strategies

Multifunctional System with Camptothecin and [12]aneN3 Units for Effective In Vivo Anti Pancreatic Cancer through Synergistic Chemotherapy, Gene Therapy, and Photodynamic Therapy

Maximizing drug cargo carrying capacity in blood circulation, controlling the in vivo fate of nanoparticles, and precisely drug release to tumor targets are the main aims of multifunctional nanomedicine-based antitumor therapy. Here we combined macrocyclic polyamine di(triazole-[12]aneN3) (M) and chemical drug camptothecin (CPT, C) through photosensitizer 1,1-dicyano-2-phenyl-2-(4-diphenylamino) phenyl-ethylene (DT) containing the cleavable disulfide (S) linkage as an all-in-one theranostic nanoprodrug, MDTSC. The corresponding compound with carbon chain (C) linkage, MDTCC, was also prepared for a comparison study. MDTSC showed the ability to carry plasmids, including the p53 tumor suppressor gene, to form lipoplexes with a size of ∼150 nm. Further addition of DOPE-PEG2k resulted in the hybrid lipoplexes MDTSC/DOPE-PEG2k@DNA, which showed good stability in blood circulation and good biocompatibility to normal cell lines. Experiments demonstrated that the hybrid lipoplexes were able to realize the successful cellular uptake and endosomal escape, to generate ROS under visible light irradiation as well as to trigger the localized release of CPT and the plasmid encoding p53 in tumor cells. In vitro, the hybrid lipoplexes showed better EGFP expression than the commercial Lipo2000, and markedly reduced tumor cell proliferation and migration rate irrespective of whether the BxPC-3 cell lines were grown on plates or 3D tumor spheroids. In vivo, the hybrid lipoplexes showed effective anticancer activity by reducing the BxPC-3 pancreatic tumor growth by 99% through the synergetic combination of chemotherapy, photodynamic therapy, and gene therapy. This research represented the first example of using a cocktail of three therapeutic approaches to achieve cooperative and effective anti pancreatic cancer treatment in vivo and in vitro.

Visual and real-time detection of the critical micelle concentration of nonionic surfactants using a supramolecular aggregate probe responsive to stable micelles

The critical micelle concentration (CMC) is considered one of the important parameters for evaluating and comparing surfactants. We have developed a novel method for detecting the CMC of nonionic surfactants, based on the environmentally responsive characteristics of cyanine dyes probes. Notably, this method exhibits high sensitivity, visual real-time monitoring capabilities, and robust anti-interference properties. The method remains effective even under alterations in pH (2-12), metal ion concentrations (0-150 mM of K+, Na+, Ca2+) and salinity levels (0-20 g/L). Furthermore, the method has been successfully applied to the analysis of real water such as lake water, water flooding, and oil-field sewage containing polymers, demonstrating its good applicability. This marks the first instance where we establish the application of detecting the CMC of nonionic surfactants using cyanine dye probes, offering a fresh perspective for developing highly sensitive, visual, real-time, and interference-resistant CMC detection methodologies.

Presenting a new fluorescent probe, methyl(10-phenylphenanthren-9-yl)sulfane sensitive to the polarity and rigidity of the microenvironment: applications toward microheterogeneous systems

A molecule, methyl(10-phenylphenanthren-9-yl)sulfane (MPPS), with a straightforward structure, has been synthesized, characterized, and explored as a new fluorescent probe for microheterogeneous systems. The photophysical properties of MPPS have been studied through experimental and theoretical calculations using the range-separated hybrid functional CAM-B3LYP in conjunction with a 6-311++g(d,p) basis set. Theoretical calculations show that the freely rotating phenyl ring forms a 94° dihedral angle with the phenanthrene ring in the ground state. Experimentally found two absorption bands correspond to the n → π* and π → π* transitions supported by the frontier molecular orbital calculations. Two excited singlet states, E-1 and E-2 (the former being more stable than the latter in the gas phase), exist with dihedral angles between the phenyl and phenanthrene rings as 142° and 133°, respectively, in the gas phase. Two emitting states in a condensed medium of varying polarities are supported by the steady-state fluorescence and fluorescence intensity decay data. Emission energies, fluorescence intensities, and excited singlet state lifetimes change with the polarity of the solvents. To support that the free rotation in the molecule is responsible for these changes, the fluorescence properties of another molecule, methyl(10-(o-tolyl)phenanthren-9-yl)sulfane (MTPS), with restricted rotation of the substituted benzene, i.e., o-tolyl ring have been studied. The fast-intensity decay component of MPPS is ascribed to the conformer in the E-1 state. The molecule has proved to be an excellent polarity probe explored to determine the critical micelle concentrations (cmc) values of different surfactants, which agree well with the literature reports. Different regions of binding isotherm (specific, non-cooperative, cooperative, and massive binding) of a gemini surfactant, 12-6-12,2Br- with bovine serum albumin (BSA) have been successfully demonstrated by the steady-state and time-resolved fluorescence and fluorescence anisotropic properties of MPPS. Docking results show that MPPS resides in the hydrophobic pocket of BSA. The fluorescence quenching of BSA by MPPS reveals the location of Trp residues of BSA. Thus, a polarity and molecular rigidity-sensitive fluorescent molecule, MPPS has been presented here that can potentially be used to monitor the changes in the microenvironment of biomolecules in different processes.

Tuning Sensing Efficacy of Oligo(phenylenevinylene) Based Chromogenic Probes: Effect of Alkyl Substituents on Metal Ion Detection at Micelle-Water Interface

In this work, we conducted a comparative analysis of the metal ion sensing capabilities of two pyridine-end oligo p-phenylenevinylene compounds featuring different alkyl substituents (-C4H9 and -C16H33) within a micelle medium. Our findings revealed a correlation between the positioning of the probe molecules within the micelle and the length of the alkyl chains, impacting their self-assembly tendencies and optical characteristics. The compound with shorter alkyl chains demonstrated a superior affinity towards Hg2+ ions, whereas exposure to the compound with longer alkyl substituent resulted in a color-changing response with both Cu2+and Hg2+ ions. Intriguingly, the sensitivity towards Hg2+ ions heightened with increasing alkyl chain length. This trend persisted in non-polar solvents like THF. The capacity to modulate sensing efficacy solely by adjusting the length of the alkyl chains represents a relatively uncommon occurrence in the existing literature. This discovery suggests promising prospects for engineering sensory devices equipped with adaptable sensitivity.

Surfactant-induced alterations in optoelectronic properties of perylene diimide dyes: modulating sensing responses in the aqueous environment

The compartmentalization effect of microheterogeneous systems, like surfactant aggregates, showcases altered optoelectronic properties of a perylene diimide-based chromogenic dye (PDI-Ala) compared to bulk water. The relatively hydrophobic microenvironment, poor hydration, and exceptionally large local concentration of dye molecules in the confined environment affect their interaction with target analytes. This realization intrigued us to investigate if micellization can modify the sensing properties (selectivity, sensitivity, response kinetics, output signal, etc.) of the encapsulated dye molecules in the aqueous medium. Response comparisons of PDI-Ala to the ionic analyte (Fe3+) and biomolecule (heparin) in aqueous and surfactant-bound states highlighted significant variations. Fe3+ interaction exhibited a "turn-off" fluorescence response in a water medium, while surfactant-bound conditions triggered "turn-on" fluorescence, enhancing selectivity at the micelle-water interface. Conversely, the native probe showed no interaction with heparin in water but displayed a turn-on fluorescence response in cetyltrimethylammonium bromide (CTAB) micelles, indicating the transformation of a silent molecule into a turn-on fluorescence sensor. This study underscores the influence of micellar environments on dye molecules, altering the sensing responses and selectivity toward analytes, crucial for applications in understanding cellular pathways and toxicity mechanisms.

Borneol-Modified Schisandrin B Micelles Cross the Blood-Brain Barrier To Treat Alzheimer's Disease in Aged Mice

Objective: Schisandrin B (Sch B) is a bioactive dibenzocyclooctadiene derizative that is prevalent in the fruit of Schisandra chinensis. Numerous studies have demonstrated that Sch B has a neuroprotective action by reducing oxidative stress and effectively preventing inflammation. It follows that Sch B is a potential treatment for Alzheimer's disease (AD). However, the drug's solubility, bioavailability, and lower permeability of the blood-brain barrier (BBB) can all reduce its efficacy during the therapy process. Therefore, this study constructed borneol-modified schisandrin B micelles (Bor-Sch B-Ms), which increase brain targeting by accurately delivering medications to the brain, effectively improving bioavailability. High therapeutic efficacy has been achieved at the pathological site. Methods: Bor-Sch B-Ms were prepared using the thin film dispersion approach in this article. On the one hand, to observe the targeting effect of borneol, we constructed a blood-brain barrier (BBB) model in vitro and studied the ability of micelles to cross the BBB. On the other hand, the distribution of micelle drugs and their related pharmacological effects on neuroinflammation, oxidative stress, and neuronal damage were studied through in vivo administration in mice. Results: In vitro studies have demonstrated that the drug uptake of bEnd.3 cells was increased by the borneol alteration on the surface of the nano micelles, implying that Bor-Sch B-Ms can promote the therapeutic effect of N2a cells. This could result in more medicines entering the BBB. In addition, in vivo studies revealed that the distribution and circulation time of medications in the brain tissue were significantly higher than those in other groups, making it more suitable for the treatment of central nervous system diseases. Conclusion: As a novel nanodrug delivery system, borneol modified schisandrin B micelles have promising research prospects in the treatment of Alzheimer's disease.

Dihydrocaffeic acid grafted chitosan self-assembled nanomicelles with enhanced intestinal transport and antioxidant properties of chicoric acid

Chicoric acid (CA) plays a crucial role as a functional factor within the realm of foods, showcasing a wide array of bioactivities. Nevertheless, its oral bioavailability is significantly limited. To optimize the intestinal absorption and bolster the antioxidant capacity of CA, a water-soluble dihydrocaffeic acid grafted chitosan copolymer (DA-g-CS) was synthesized using a conventional free radicals system, and subsequently utilized for the encapsulation of CA within self-assembled nanomicelles (DA-g-CS/CA). The average particle size of DA-g-CS/CA was 203.3 nm, while the critical micelle concentration was 3.98 × 10-4 mg/mL. Intestinal transport studies revealed that DA-g-CS/CA penetrated cells via the macropinocytosis pathway, exhibiting the cellular uptake rate 1.64 times higher than that of CA. This substantial enhancement in the intestinal transport of CA underscores the significant improvements achieved through DA-g-CS/CA delivery. The pharmacokinetic results demonstrated that DA-g-CS/CA exhibited a remarkable bioavailability 2.24 times that of CA. Furthermore, the antioxidant assessment demonstrated that DA-g-CS/CA exhibited exceptional antioxidant properties in comparison to CA. It demonstrated enhanced protective and mitigating effects in the H2O2-induced oxidative damage model, while also displaying a stronger emphasis on protective effects rather than attenuating effects. These findings aim to establish a solid theoretical foundation for the advancement of CA in terms of its oral absorption and the development of functional food products.

Preparation of Self-Assembled, Curcumin-Loaded Nano-Micelles Using Quarternized Chitosan-Vanillin Imine (QCS-Vani Imine) Conjugate and Evaluation of Synergistic Anticancer Effect with Cisplatin

Nano-micelles are self-assembling colloidal dispersions applied to enhance the anticancer efficacy of chemotherapeutic agents. In this study, the conjugate of quarternized chitosan and vanillin imine (QCS-Vani imine) was synthesized using the reaction of a Schiff base characterized by proton-NMR (1HNMR), UV-Vis spectroscopy, and FT-IR. The critical micelle concentration (CMC), particle size, and zeta potential of the resulting product were determined. The QCS-Vani imine conjugate was used as a carrier for the development of curcumin-loaded nano-micelles, and their entrapment efficiency (%EE), drug-loading capacity (%LC) and in vitro release were investigated using HPLC analysis. Moreover, the nano-micelles containing curcumin were combined with various concentrations of cisplatin and evaluated for a possible anticancer synergistic effect. The anticancer activity was evaluated against lung cancer A549 and mouse fibroblast L929 cell lines. The percent yield (%) of the QCS-Vani imine conjugate was 93.18%. The curcumin-loaded QCS-Vani imine nano-micelles were characterized and found to have a spherical shape (by TEM) with size < 200 nm (by DLS) with high %EE up to 67.61% and %LC up to 6.15 ± 0.41%. The loaded lyophilized powder of the nano-micelles was more stable at 4 °C than at room temperature during 120 days of storage. pH-sensitive release properties were observed to have a higher curcumin release at pH 5.5 (cancer environment) than at pH 7.4 (systemic environment). Curcumin-loaded QCS-Vani imine nano-micelles showed higher cytotoxicity and selectivity toward lung cancer A549 cell lines and exhibited lower toxicity toward the normal cell (H9C2) than pure curcumin. Moreover, the curcumin-loaded QCS-Vani imine nano-micelles exhibited an enhanced property of inducing cell cycle arrest during the S-phase against A549 cells and showed prominently induced apoptosis in lung cancer cells compared to that with curcumin. The co-treatment of cisplatin with curcumin-loaded QCS-Vani imine nano-micelles presented an enhanced anticancer effect, showing 8.66 ± 0.88 μM as the IC50 value, in comparison to the treatment with cisplatin alone (14.22 ± 1.01 μM). These findings suggest that the developed QCS-Vani imine nano-micelle is a potential drug delivery system and could be a promising approach for treating lung cancer in combination with cisplatin.

Improve BBB Penetration and Cytotoxicity of Palbociclib in U87-MG Glioblastoma Cells Delivered by Dual Peptide Functionalized Nanoparticles

Palbociclib (PBC) is an FDA-approved CDK4/6 inhibitor used for breast cancer treatment. PBC has been demonstrated its ability to suppress the proliferation of glioma cells by inducing cell cycle arrest. However, the efflux transporters on the blood-brain barrier (BBB) restricts the delivery of PBC to the brain. The nano-delivery strategy with BBB-penetrating and glioma-targeting abilities was designed. Poly(lactide-co-glycolide)-poly(ethylene glycol) (PLGA-PEG) was functionalized with the potential peptide, T7 targeting peptide and/or R9 penetrating peptide, to prepare PBC-loaded nanoparticles (PBC@NPs). The size of PBC@NPs was in the range of 168.4 ± 4.3-185.8 ± 4.4 nm (PDI < 0.2), and the zeta potential ranged from -17.8 ± 1.4 mV to -14.3 ± 1.0 mV dependent of conjugated peptide. The transport of PBC@NPs across the bEnd.3 cell model was in the order of dual-peptide modified NPs > T7-peptide modified NPs > peptide-free NPs > free PBC, indicating facilitated delivery of PBC by NPs, particularly the T7/R9 dual-peptide modified NPs. Moreover, PBC@NPs significantly enhanced U87-MG glioma cell apoptosis by 2.3-6.5 folds relative to PBC, where the dual-peptide modified NPs was the most effective one. In conclusion, the PBC loaded dual-peptide functionalized NPs improved cellular uptake in bEnd.3 cells followed by targeting to U87-MG glioma cells, leading to effective cytotoxicity and promoting cell death.

Interaction mode of hydroxypropyl-β-cyclodextrin with vaccine adjuvant components Tween 80 and Triton X-100 revealed by fluorescence increasing-quenching analysis

The nonionic surfactants Tween 80 (Tw80) and Triton X-100 (TX100), which are used as components of adjuvants, were used with bovine serum albumin (BSA) and hydroxfypropyl-β-cyclodextrin (HP-β-CD) as model antigens. The interaction patterns of Tw80 and TX100 with the hydrophobic cores of the model antigens were investigated. The fluorescence of 8-anilinonaphthalene-1-sulfonic acid (ANS), a hydrophobic fluorescent probe, was used to evaluate the effect of surfactants on each model antigen. A Hanes Woolf plot was used to analyze the adsorption of ANS to BSA, and an activator-inhibitor model was used to analyze the concentration-dependent increase and decrease of ANS fluorescence intensity. For BSA, TX100 occupies the ANS binding site inside the BSA hydrophobic core, while Tw80 does not contribute to the ANS binding site in the hydrophobic core. For HP-β-CD, the ANS concentration required for analyzable fluorescence intensity extended to the range where ANS concentration-dependent quenching was not negligible. Using the activator inhibitor model, we were able to separate the activators and inhibitors of ANS fluorescence and evaluate the affinity of ANS for HP-β-CD and surfactants. The results obtained showed that TX100 provided a hydrophobic environment to the ANS while being encapsulated by HP-β-CD, while Tw80 did not interact with HP-β-CD and provided a hydrophobic environment to the ANS independently of each other. The interpretations obtained were corroborated by the determination of the CMC of TX100 and Tw80, the effect of salt on ANS fluorescence, and ¹H-NMR and ROESY. In summary, the results showed that the large hydrophilic head of Tween, composed of sorbitan and PEG chains, floated in the aqueous phase like a balloon, while Triton pierced the hydrophobic core of the antigen like a spear. In both BSA and HP-β-CD model antigens, TX100 impinged on the hydrophobic core.