Synthesis of C3-symmetric star shaped amphiphiles for drug delivery applications

C 3-symmetric star-shaped aromatic compounds are known to possess unique characteristics which facilitate their industrial and biomedical applications. Herein, we report the design, synthesis, self-assembly and drug/dye delivery capabilities of C3-symmetric, hexa-substituted benzene-based amphiphiles. The synthesis of the hexa-substituted C3-symmetric core involves C-acetylation of phloroglucinol to yield the corresponding tri-acetyl derivative. This was further subjected to O-propargylation, followed by the carbonyl reduction of acetyl groups to yield the central core. Various hydrophilic (mPEG) and lipophilic units were then incorporated into this core via click and esterification reactions, respectively, to produce a new type of star shaped amphiphiles. So the obtained amphiphilic architectures have a tendency to aggregate in an aqueous medium forming nanosized assemblies with an inner hydrophobic core, allowing the substituents to control the tension-active properties. The critical aggregation concentration of the amphiphiles was evaluated by fluorescence measurement using the dye Nile red as a fluorescent probe. The hydrodynamic diameter of self-assembled aggregates in aqueous solution was studied by dynamic light scattering, while the actual size and morphology were determined by cryo-transmission electron microscopy (cryo-TEM) analysis. The physicochemical properties of the amphiphiles suggested their suitability for exploring their drug delivery applications. In this endeavor, the amphiphiles were utilized for the encapsulation of model hydrophobic entities and studying their subsequent release from their hydrophobic core in a controlled manner. The transport potential of the synthesised amphiphiles was explored for transdermal drug delivery. Furthermore, cytotoxicity studies were conducted using MCF7 and HeLa cells, which indicated that the nanocarriers had no toxic effect on the cells.

Trends in the Diversification of the Detergentome

Detergents are amphiphilic molecules that serve as enabling steps for today's world applications. The increasing diversity of the detergentome is key to applications enabled by detergent science. Regardless of the application, the optimal design of detergents is determined empirically, which leads to failed preparations, and raising costs. To facilitate project planning, here we review synthesis strategies that drive the diversification of the detergentome. Synthesis strategies relevant for industrial and academic applications include linear, modular, combinatorial, bio-based, and metric-assisted detergent synthesis. Scopes and limitations of individual synthesis strategies in context with industrial product development and academic research are discussed. Furthermore, when designing detergents, the selection of molecular building blocks, i. e., head, linker, tail, is as important as the employed synthesis strategy. To facilitate the design of safe-to-use and tailor-made detergents, we provide an overview of established head, linker, and tail groups and highlight selected scopes and limitations for applications. It becomes apparent that most recent contributions to the increasing chemical diversity of detergent building blocks originate from the development of detergents for membrane protein studies. The overview of synthesis strategies and molecular blocks will bring us closer to the ability to predictably design and synthesize optimal detergents for challenging future applications.

Fabrication of hydrolase responsive diglycerol based Gemini amphiphiles for dermal drug delivery applications

Since biocatalysts manoeuvre most of the physiological activities in living organisms and exhibit extreme selectivity and specificity, their use to trigger physicochemical change in polymeric architectures has been successfully used for targeted drug delivery. Our major interest is to develop lipase responsive nanoscale delivery systems from bio-compatible and biodegradable building blocks. Herein, we report the synthesis of four novel non-ionic Gemini amphiphiles using a chemo-enzymatic approach. A symmetrical diglycerol has been used as a core that is functionalised with alkyl chains for the creation of a hydrophobic cavity, and for aqueous solubility (polyethylene glycol) monomethyl ether (mPEG) is incorporated. Such systems can exhibit a varied self-assembly behaviour leading to the observance of different morphological structures. The aggregation behaviour of the synthesised nanocarrier was studied by dynamic light scattering (DLS) and critical aggregation concentration (CAC) measurements. The nanotransport potential of amphiphiles was investigated for hydrophobic guest molecules, i.e. Nile red, nimodipine and curcumin. Cytotoxicity of the amphiphiles was studied using HeLa and MCF7 cell lines at different concentrations, i.e. 0.05, 0.1, and 0.5 mg mL-1. All nanocarriers were found to be non-cytotoxic up to a concentration of 0.1 mg mL-1. Confocal laser scanning microscopy (cLSM) study suggested the uptake of encapsulated dye in the cytosol of the cancer cells within 4 h, thus implying that amphiphilic systems can efficiently transport hydrophobic drug molecules into cells. The biomedical application of the synthesised Gemini amphiphiles was also investigated for dermal drug delivery. In addition, the enzyme-mediated release study was performed that demonstrated 90% of the dye is released within three days. All these results supported the capability of nanocarriers in drug delivery systems.

Newer Non-ionic A2 B2 -Type Enzyme-Responsive Amphiphiles for Drug Delivery

A new series of nonionic gemini amphiphiles have been synthesized in a multi-step chemoenzymatic approach by using a novel A₂ B₂ -type central core consisting of conjugating glycerol and propargyl bromide on 5-hydroxy isophthalic acid. A pair of hydrophilic monomethoxy poly(ethylene glycol) (mPEG) and hydrophobic linear alkyl chains (C₁₂ /C₁₅ ) were then added to the core to obtain amphiphilic architectures. The aggregation tendency in aqueous media was studied by dynamic light scattering, fluorescence spectroscopy and cryogenic transmission electron microscopy. The nanotransport potential of the amphiphiles was studied for model hydrophobic guests, that is, the dye Nile Red and the drug Nimodipine by using UV/Vis and fluorescence spectroscopy. Evaluation of the viability of amphiphile-treated A549 cells showed them to be well tolerated up to the concentrations studied. Being ester based, these amphiphiles exhibit stimuli-responsive sensitivity towards esterases, and a rupture of amphiphilic architecture was observed in the presence of immobilized Candida antarctica lipase (Novozym 435), thus facilitating release of the encapsulated guest from the aggregate.

Non-ionic small amphiphile based nanostructures for biomedical applications

Self-assembly of non-ionic amphiphilic architectures into nanostructures with defined size, shape and morphology has garnered substantial momentum in the recent years due to their extensive applications in biomedicine. The manifestation of a wide range of morphologies such as micelles, vesicles, fibers, tubes, and toroids is thought to be related to the structure of amphiphilic architectures, in particular, the choice of the hydrophilic and hydrophobic parts. In this review, we look at different types of non-ionic small amphiphilic architectures and the factors that influence their self-assembly into various nanostructures in aqueous medium. In particular, we focus on the explored structural parameters that guide the formation of various nanostructures, and the ways these structures can be used in applications ranging from drug delivery to cell imaging.

Stimuli-responsive non-ionic Gemini amphiphiles for drug delivery applications

This paper shows the synthesis of stimuli responsive Gemini amphiphiles sensitive to Glutathione and hydrolase.

Oligo-glycerol based non-ionic amphiphilic nanocarriers for lipase mediated controlled drug release

A new series of oligo-glycerol based amphiphiles have been synthesized for drug delivery.