Measurement of cytotoxicity and irritancy potential of sugar-based surfactants on skin-related 3D models

Silk Protein-Based Nanoporous Microsphere for Controllable Drug Delivery through Self-Assembly in Ionic Liquid System

Ionic liquids (ILs) showed a promising application prospect in the field of biomedicine due to their unique recyclability, modifiability, and structure adjustability. In this study, nanoporous microsphere of silk protein and blending with poly(d,l-lactic acid) as model drug delivery was fabricated, respectively, through an IL-induced self-assembly method. Their morphology, structure, and thermal properties were comparably investigated through scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, differential scanning calorimetry, X-ray diffraction, and thermogravimetric analyses, and the interaction mechanisms were also discussed to elucidate the effect of structure on drug delivery kinetics. The pure protein exhibited a bigger nanopore size in the microsphere compared to the composite one, facilitating more effective drug loading up to 88.7%. However, drug release was over 53.5% for the composite during initial 4 h, while pure protein was only about half of the composite. Both of them exhibited sustained slow release after 24 h and anticancer efficacy. Furthermore, the favorable compatibility between drug and microsphere vehicle was found and experienced improved thermal stability upon encapsulation, which could protect the drug molecules in high temperature at 200 °C. When the protein and its composite self-assembled to microspheres in ILs due to electrostatic and hydrophobic interaction, the drug could be infiltrated into the nanoporous matrix through biophysical action, and the protein structure displayed reversible transition during delivery. The sustained slow release from pure SF was attributed to the high β-sheet block action and strong drug-protein interactions, whose strength could be tuned through blending poly(d,l-lactic acid) with protein. These findings indicated that the SF-based nanoporous microspheres formed from IL self-assembled system are an ideal and potential drug delivery vehicle which can be incorporated into various biomaterials in the future.

Surface Properties and Liquid Crystal Properties of Alkyltetra(oxyethyl) β-d-Glucopyranoside

Hydrophilic alkyl polyglycosides (APGs) and alkyl glycosides (AGs) with anomeric pure are a class of important substitutes for petroleum-based surfactants. Improving their water solubility should make such hydrophilic glycosurfactants have more excellent potential application value. To solve the inherent problem of poor water solubility of traditional alkyl β-d-glucopyranoside (5), a series of alkyltetra(oxyethyl) β-d-glucopyranosides (4a-4g, n = 7-18) were successfully synthesized by introducing tetra(oxyethylene) fragments to carry out the structural modification. The relationship between the related structure and the physicochemical properties was further investigated, including their hydrophilic-lipophilic balance (HLB), water-solubility, foaming performance, emulsification, hygroscopicity, surface activity, and thermotropic/lyotropic liquid crystal phase behavior. The results showed that the water solubility gradually decreased as the alkyl chain length increased due to the gradual decrease of their HLB number. Octadecyltetra(oxyethyl) β-d-glucopyranoside (4g, n = 18) was found to be insoluble in water at 25 °C. Taken together, long-chain alkyl glycosides had good foaming properties and excellent emulsifying properties. Among them, dodecyltetra(oxyethyl) β-d-glucopyranoside (4d, n = 12) had the best foaming performance. In the rapeseed oil/water system, cetyltetra(oxyethyl) β-d-glucopyranoside (4f, n = 16) had the best emulsifying ability. With the increase of the alkyl chain length, the critical micelle concentration (C_cmc), γ_cmc, Γ_max, and hygroscopicity of this series of glycosides showed a downward trend. Differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) showed that the thermal stability increased with the increase of the alkyl chain length, and alkyltetra(oxyethyl) β-d-glucopyranosides (4d-4g, n = 12-18) had the corresponding melting points and clearing points. Alkyltetra(oxyethyl) β-d-glucopyranosides (4b-4g, n = 8-18) formed a smectic phase with a typical fan-shaped and focal conic texture during the cooling process. In the water contact experiments, it was found that glycosides (4b-4g, n = 8-18) at high concentrations transformed into various lyotropic liquid crystal including hexagonal phase, bicontinuous cubic phase, and lamellar phase phases. Therefore, such green nonionic glycosurfactants alkyltetra(oxyethyl) β-d-glucopyranosides should have potential practical application prospects.

Dynamic Surface Properties of Eco-Friendly Cationic Saccharide Surfactants at the Water/Air Interface

The equilibrium surface properties and dynamic surface tension (DST) are presented for aqueous solutions of novel eco-friendly cationic saccharide surfactants (CnDGPB) at different concentrations and temperatures. The equilibrium surface tension, the DST, the effective diffusion coefficients and the activation barrier of the surfactants are calculated and analyzed. In addition, the general diffusion mechanism of the surfactants is proposed. The equilibrium surface tension results show that the γCMC and CMC values decrease with increasing temperature. The interactions (repulsion forces) between the hydrophobic groups and water molecules decrease with increasing temperature, which results in increased HLB values. This phenomenon causes a higher Amin and lower Γmax. The DST of CnDGPB below and above the CMC is tested by the maximum bubble pressure method at temperature from 25 °C to 45 °C. The adsorption activation energy of CnDGPB is between 3 kJ/mol and 20 kJ/mol. The results show that the final stages of the DST decays are consistent with the activated diffusion-controlled adsorption mechanism.

Three-Dimensional Epidermal Model from Human Hair Follicle-Derived Keratinocytes

Three-dimensional (3D) epidermal models reconstructed from human skin-derived keratinocytes have been utilized as an alternative to animal testing and models, not only in toxicology, but also in skin biology. Although there are currently several reconstructed human epidermis (RHE) models commercially available, the donors of the keratinocytes are not identified in these models. A tailor-made system is needed to investigate the individual differences in RHE derived from each donor.It is possible to make an individual RHE using each donor's keratinocytes, which are usually obtained by invasive procedures such as skin excision or biopsy. To overcome this drawback, we established an RHE model using keratinocytes derived from plucked hair follicles as a less invasive procedure under conditions without feeder cells, serum, or matrix proteins. In this chapter, we provide a method of isolation and two-dimensional (2D) culture of keratinocytes derived from adult human plucked hair follicles including the outer root sheath (ORS). We also provide a detailed protocol for establishing an RHE model by culturing the keratinocytes under a 3D culture condition. We believe that our less invasive technique will provide a useful tool for investigating individual RHE in both normal and disease settings.

Review: Endogenously Produced Volatiles for In Vitro Toxicity Testing Using Cell Lines

Due to the ∼86,000 chemicals registered under the Toxic Substances Control Act and increasing ethical concerns regarding animal testing, it is not economically or technically feasible to screen every registered chemical for toxicity using animal-based toxicity assays. To address this challenge, regulatory agencies are investigating high-throughput screening in vitro methods to increase speed of toxicity testing, while reducing the overall cost. One approach for rapid toxicity testing currently being investigated is monitoring of volatile emissions produced by cell lines in culture. Such a metabolomics approach would measure gaseous emissions from a cell line and determine if such gaseous metabolites are altered upon exposure to a xenobiotic. Herein, we describe the history and rationale of monitoring endogenously produced volatiles for identification of pathologic conditions, as well as emerging applications in toxicity testing for such an approach.