In relation to the following article "DLS and zeta potential - What they are and what they are not?" Journal of Controlled Release, 2016, 235, 337-351

Adsorption of Polyetheramine-230 on Expansive Clay and Structure Properties Investigation

Polyetheramine (PEA) is a swelling inhibitor used to address engineering challenges arising from the interaction between montmorillonite (Mt) and water. This study comprehensively investigates the adsorption characteristics of PEA on three representative expansive clay samples: Na-Mt, Ca-Mt, and engineered expansive soil. Additionally, the desorption of exchangeable ions is examined. The findings reveal that a two-stage adsorption kinetic model and a pseudo-second-order kinetic model can properly describe the adsorption kinetics of PEA on expansive clays. PEA exhibits a strong capacity for ion exchange with sodium ions, while the exchange capacity for calcium ions is limited. Both protonated and non-protonated PEA contribute to rapid adsorption processes. The adsorption isotherms are well-fitted by the Langmuir and Freundlich models, with the Langmuir model being reasonable. At lower equilibrium concentrations, a higher proportion of the adsorption amount is attributed to ion exchange compared to higher equilibrium concentrations. Ion exchange emerges as the primary factor contributing to the adsorption of PEA on Na-Mt, whereas the adsorption of PEA on Ca-Mt and expansive soil is primarily attributed to physical adsorption by non-protonated PEA. X-ray diffraction results reveal significant intercalation effects of PEA as they penetrate the interlayer space and hinder interlayer ion hydration. Fourier transform infrared spectrum results demonstrate that the adsorption of PEA minimally impacts the framework of Mt structural units but primarily reduces the adsorbed water content. Clay-PEA composites exhibit a decreased affinity for water. Zeta potential experiments indicate that the adsorption of PEA significantly diminishes the surface potential of clay-PEA composite particles, effectively inhibiting their hydration dispersion.

Advanced theranostic nanoplatforms for hypericin delivery in the cancer treatment

Biomodified coated-lipid vesicles were obtained using the DPPC lipid (L) and F127 copolymer linked covalently with spermine (SN), biotin (BT), and folic acid (FA), resulting in LF127-SN, LF127-BT, and LF127-FA nanoplatforms. The photosensitizer hypericin (HY) was incorporated into the nanosystem by a thin-film method and characterized by dynamic light scattering, zeta potential, encapsulation efficiency, and transmission electronic microscopy. The results provided a good level of stability for all nanoplatforms for at least 5 days as an aqueous dispersion. The in vitro serum stability showed that the HY-loaded LF127-SN has a lower tendency to form complexes with BSA protein than with its analogs. LF127-SN was the most stable HY formulation, followed by LF127-BT and LF127-FA, confirmed by the association constant (Kd) values: 600 μmol L-1, 1100 μmol L-1, 515 μmol L-1, and 378 μmol L-1 for LF127, LF127 FA, LF127-BT, and LF127-SN, respectively. The photodynamic potential of HY was accessed by cytotoxicity assays using Caco-2, B16-F10, L-929, and HaCat cells. HY-loaded LF127-SN revealed a significant increase in the selectivity compared to other nanoplatforms. HY-loaded in LF127-BT and LF127-SN showed distinct uptake and biodistribution after 2 h of intravenous application. All biomodified coated-lipids showed satisfactory metabolism within 72 h after application, without significant accumulation or residue in any vital organ. These results suggest that incorporating HY-loaded in these nanosystems may be a promising strategy for future applications, even with a small amount of binders to the coating copolymer (0.02% w/v). Furthermore, these results indicate that the LF127-SN showed remarkable superiority compared to other evaluated systems, being the most distinct for future photodynamic therapy and theranostic applications.

Biocompatibility, Cytotoxicity, Antimicrobial and Epigenetic Effects of Novel Chitosan-Based Quercetin Nanohydrogel in Human Cancer Cells

Background

Previous studies have reported that quercetin (Q) has a potential antibacterial and anticancer activity. However, its application is limited by many important factors including high hydrophobicity and low absorption.

Methodology

In the current study, we synthesized and characterized (Patent) a novel chitosan-based quercetin nanohydrogel (ChiNH/Q). Encapsulation efficiency was confirmed by UV/VIS spectrophotometer. Physicochemical characterization of ChiNH/Q was assessed by PDI, DLS, SEM, FTIR, and XRD. The toxicity of the ChiNH/Q against five strains of the pathogen and HepG2 cells was examined. Moreover, the quantification of ChiNH/Q on genomic global DNA methylation and expression of DNMTs (DNMT1/3A/3B) in HepG2 cancer cells were evaluated by ELISA and real-time PCR, respectively.

Results

Under the SEM-based images, the hydrodynamic size of the ChiNH/Q was 743.6 nm. The changes in the PDI were 0.507, and zeta potential was obtained as 12.1 mV for ChiNH/Q. The FTIR peak of ChiNH/Q showed the peak at 627 cm⁻¹ corresponded to tensile vibrational of NH₂-groups related to Q, and it is the indication of Q loading in the formulation. Moreover, XRD data have detected the encapsulation of ChiNH/Q. The ChiNH/Q showed a potent antimicrobial inhibitory effect and exerted cytotoxic effects against HepG2 cancer cells with IC₅₀ values of 100 µg/mL. Moreover, our data have shown that ChiNH/Q effectively reduced (65%) the average expression level of all the three DNMTs (p<0.05) and significantly increased (1.01%) the 5-methylated cytosine (5-mC) levels in HepG2 cells.

Conclusion

Our results showed for the first time the bioavailability and potentiality of ChiNH/Q as a potent antimicrobial and anticancer agent against cancer cells. Our result provided evidence that ChiNH/Q could effectively reduce cellular DNMT expression levels and increase genomic global DNA methylation in HepG2 cancer cells. Our results suggest a potential clinical application of nanoparticles as antimicrobial and anticancer agents in combination cancer therapy.

Evaluation of yam (Dioscorea rotundata) mucilage as a stabilizer in the production of mango nectar

Instability in fruit drinks is a phenomenon that affects sensory and physical-chemical properties, which consumers perceive as lack of quality. Yam mucilage was evaluated as a stabilizer in the production of mango nectar. In addition, physicochemical characteristics, physical and rheological stability were determined. A completely randomized design with factorial arrangement (2 × 4) was utilized. The factors were the concentration of the stabilizers, and the yam mucilage:carboxymethylcellulose ratio. Results showed that physicochemical properties comply with Colombian regulations and, as the proportion of carboxymethylcellulose decreased in the mucilage:CMC ratio, the absolute value of zeta potential decreased. Rheologically, mango nectar exhibit overall shear-thinning (pseudoplastic) and thixotropic properties. Results indicate that yam mucilage should be used in a mixture with other hydrocolloids.

One-Step Synthesis of Polypyrrole-Coated Gold Nanoparticles for Use as a Photothermally Active Nano-System

OBJECTIVE

This paper introduces a simple one-step and ultra-fast method for synthesis of highly photothermally active polypyrrole-coated gold nanoparticles. The synthesis process is so simple that the reaction is very fast without the need for any additives or complicated steps.

METHODOLOGY

Polypyrrole-coated gold nanoparticles (AuPpy NPs) were synthesized by reacting chloroauric acid (HAuCl4) with pyrrole (monomer) in aqueous medium at room temperature. These nanoparticles were characterized by UV-visible-NIR spectrometry, transmission electron microscopy (TEM), AC conductivity, zeta sizer and were evaluated for dark cytotoxicity and photocytotoxicity using human hepatocellular carcinoma (HepG2) cell line as a model for cancer cells.

RESULTS

The synthesized AuPpy NPs showed a peak characteristic for gold nanoparticles (530-600 nm, molar ratio dependent) and a wide absorption band along the visible-NIR region with intensity about triple or even quadruple that of polypyrrole synthesized by the conventional FeCl3 method at the same concentration and under the same conditions. TEM imaging showed that the synthesized AuPpy NPs were composed of spherical or semi-spherical gold core(s) of about 4-10 nm coated with distinct layer(s) of polypyrrole seen either loosely or in clusters. Mean sizes of the synthesized nanoparticles range between ~25 and 220 nm (molar ratio dependent). Zeta potentials of the AuPpy NPs preparations indicate their good colloidal stability. AC conductivity values of AuPpy NPs highly surpass that of Ppy prepared by the conventional FeCl3 method. AuPpy NPs were non-toxic even at high concentrations (up to 1000 µM pyrrole monomer equivalent) under dark conditions. Unlikely, light activated the photothermal activity of AuPpy NPs in a dose-dependent manner.

CONCLUSION

This method simply and successfully synthesized AuPpy NPs nanoparticles that represent a safe alternative photothermally active multifunctional tool instead of highly toxic and non-biodegradable gold nanorods.

A novel self-nanoemulsifying drug delivery system for curcumin used in the treatment of wound healing and inflammation

The main objective of this study was to develop and evaluate self-nanoemulsifying drug delivery system (SNEDDS) of curcumin (Cur) to enhance their solubility as well as improve skin permeation; and evaluate wound healing potential of Cur via SNEDDS in comparison with standards pure eucalyptus oil-SNEDDS (Euc-SNEDDS), pure curcumin suspension (Cur-S), and standard fusidic acid followed by their anti-inflammatory action. Curcumin-loaded different SNEDDS formulations were formulated through aqueous phase titration method and the zones of SNEDDS were recognized by the construction of phase diagrams. Eucalyptus oil, Tween 80 (surfactant), and Transcutol HP (co-surfactant) were selected on the basis of their solubility and highest nanoemulsion region. Characterization of thermodynamic stability for Cur-loaded SNEDDS was evaluated by its globule size, zeta potential, polydispersity index, viscosity, % transmittance, refractive index, and surface morphology. Cur-SNEDDS (Cur-SN4) was optimized and selected on the basis of their excellent physicochemical parameters for in vivo activity. The particle size (59.56 ± 0.94 nm), % transmittance (99.08 ± 0.07%), and PDI (0.207 ± 0.011 were observed for optimized Cur-SNEDDS. TEM and SEM showed their smooth and spherical shape of the morphological characterization with zeta potential (- 21.41 ± 0.89), refractive index (1.341 ± 0.06), and viscosity (11.64 ± 1.26 cp) for optimized Cur-SNEDDS. Finally, optimized Cur-SNEDDS was used to enhance skin permeation with improvement in the solubility of Cur. However, optimized Cur-SNEDDS showed significant wound healing activity as compared with pure eucalyptus oil and Cur-S on topical application. Optimized Cur-SNEDDS showed healing of wound as compared to standard fusidic acid. Optimized Cur-SNEDDS exhibited no signs of inflammatory cells on the histopathological studies of treated rats which were recommended the safety and non-toxicity of Cur-SNEDDS. Newly developed Cur-SNEDDS could be successfully used to enhance Cur-solubility and skin permeation, as well as suggested a potential role of Cur-SNEDDS for better improvement of wound healing activity followed by anti-inflammatory action of Cur via topical application.

The Influence of Formulation Ratio and Emulsifying Settings on Tri-Fuel (Diesel–Ethanol–Biodiesel) Emulsion Properties

In this study, an alternative fuel for compression ignition (CI) engines called tri-fuel emulsion was prepared using an ultrasonic emulsifier. The objective of the study is to investigate the effect of emulsifying settings and formulation ratio on the physicochemical properties of tri-fuel emulsions. Design of experiment (DOE) with the two-level factorial design was employed to analyze the effect of emulsifying settings such as time, amplitude, and cycle along with the variation ratio of tri-fuel emulsion components as control factors. Numbers of responses identified were important parameters that may contribute to microexplosion phenomenon in CI engine. Analysis of variance (ANOVA) was carried out for each response, and the results indicated that density, dynamic viscosity, surface tension, and average droplet size were influenced by specific preparation control factors. Furthermore, interaction among the control factors was found to affect the responses as well. Interaction means the effect of two factors together is different than what would be expected from each factor separately. Besides, the stability of the tri-fuel emulsion was observed for three months. Furthermore, a qualitative approach with a multiobjective lens digital microscope revealed the geometry of freshly made dispersed tri-fuel emulsion droplets. Microscopic examination on tri-fuel emulsion droplets has shown that the dispersed ethanol capsulated within diesel with the help of biodiesel is similar to a water in diesel emulsion and is dissimilar to commercial diesel mixed with fatty acid methyl esters found in the market.

Ocular Application of Dirithromycin Incorporated Polymeric Nanoparticles: an In Vitro Evaluation

Objectives

Ocular drug delivery is a difficult challenge especially with topical intillation which results in rapid drainage and non-productive drug absorption. For the improvement of the pre-corneal retention time and enhancing the corneal permeability, colloidal drug delivery systems play an important role in enhancement of the ocular bioavailability. In this study, dirithromycin incorporated Kollidon^® SR-based polymeric nanoparticles, an antibacterial agent, were formulated for the efficient treatment of severe ocular bacterial infections.

Materials and Methods

In this study, dirithromycin was incorporated into the Kollidon^® SR-based nanoparticles by spray drying method. In vitro characteristic properties were evaluated in detail during the storage period of three months at three different conditions.

Results

The results of in vitro analyses revealed that characteristic properties of the particles were remained unchanged during the storage period of three months.

Conclusion

Kollidon^® SR-based polymeric nanoparticles are good candidates for drug delivery systems in the treatment of severe ocular bacterial infections with dirithromycin.