Series Of Physicochemical Properties Research Articles

Development and evaluation of a novel biodegradable implants with excellent inflammatory response suppression effect by hot-melt extrusion

PurposeDexamethasone (Dex) is a widely used drug for the treatment of inflammatory and autoimmune conditions, however, long-term systemic use of Dex is associated with serious adverse effects. The objective of the present study was to develop an implantable device to avoid side effects and realize a controlled release of Dex at the implant site. MethodsHydrophobic Dex was incorporated into biodegradable polyesters derived from PCL and Pluronic® L64 (PCL-Pluronic L64-PCL, PCLC) by hot-melt extrusion (HME) method to prepare Dex/PCLC implantable devices. Drug loading and encapsulation efficiency, a series of physicochemical properties, and in vivo features of the implants were studied. ResultsThe maximum value of the drug loading and encapsulation efficiency for the Dex/PCLC implants were up to 47% and 94%, respectively. Incorporation of Dex resulted in accelerated crystallization of PCLC, decreased the wettability, increased contact angles and viscosity, and accelerated Dex release rate and degradation rate from the implants in vivo. Moreover, Dex/PCLC implants showed excellent biocompatibility. Furthermore, the inflammatory response to the Dex/PCLC implants was less severe than that to the positive control group. ConclusionAll these results suggested that Dex/PCLC implants might be a safe and controlled local drug delivery system with excellent inflammatory response suppression effect.

Targeted Chemotherapy for Breast Cancer Using an Intelligent Doxorubicin-Loaded Hexapeptide Hydrogel.

Self-assembling peptide hydrogels have a high water content, good biocompatibility and have become a competitive research object in the fields of tissue engineering, cancer treatment and drug delivery. In our research, a hexapeptide with high pH sensitivity was designed and synthesized by utilizing a solid-phase synthesis method. Under physiological conditions, the peptide could self-assemble into a hydrogel. When it reached the tumor acidic microenvironment, the peptide was degraded and doxorubicin was released to exert its antitumor effect. A series of physicochemical properties were investigated, including gelling ability, secondary structure, micromorphology, rheological properties and drug release studies. The results illustrated that PIDO peptide hydrogel has good pH responsiveness and injectability. In vitro cytotoxicity experiments and in vivo antitumor experiments showed that PIDO peptide hydrogel has a highly effective therapeutic effect on tumor cells and is less toxic to normal tissues. Our research provides a promising option for targeted drug delivery and sustainable release.

Fabrication of alignment polycaprolactone scaffolds by combining use of electrospinning and micromolding for regulating Schwann cells behavior

In the present study, a new approach for fabricating micropatterned polycaprolactone (PCL) scaffolds with ridge/groove structure on the surface was developed by combining use of electrospinning and micromolding method. A series of physicochemical properties, including morphology, wettability, component, crystal pattern and mechanical properties, of prepared PCL scaffolds were characterization, respectively. Stability of the micropatterned PCL scaffolds was measured using phosphate buffer solution immersion for a certain period. Then, the regulating effects of the micropatterned PCL scaffolds on attachment, orientation and normal biological function of Schwann cells were evaluated. And the protein adsorption behavior in various PCL scaffolds was also detected. The results showed that the micropatterned PCL scaffolds demonstrated a porous micro/nano complex structure with enhanced hydrophobicity and mechanical properties as a function of electrospun flow-rate of PCL solution. The micropatterned PCL scaffolds possessed good stability and could effectively regulate the attachment and orientation of Schwann cells at the early stage after cell culture. Importantly, the electrospun flow-rate of PCL solution was found to play an important role in scaffold properties, cell behavior and protein adsorption. The micropatterned scaffolds with a flow-rate of PCL solution at 0.12 mL h-1 demonstrated the better regulation on Schwann cells attachment and alignment without negatively affect the normal biological function of the cells. To the best of our knowledge, this is the first report of combining use of electrospinning and micromolding method for preparing artificial nerve implants. The study is anticipated to have potential application in peripheral nerve and other tissue engineering. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3123-3134, 2018.

Synthesis and properties of Alkyl α-D-Galactopyranoside

ABSTRACTAlkyl α-D-galactopyranosides are sugar-based nonionic surfactants, and it is necessary to research their structure–property relationships since it is not quite clear that the change of the alkyl chain length has effects on a series of physicochemical properties. Here, alkyl α-D-galactopyranosides were prepared by galactose and alcohols through three steps including acetylation, coupling with alcohols in the presence of a catalyst stannic chloride, and deprotection. Furthermore, their water solubility and other properties were investigated. Alkyl α-D-galactopyranosides (4a ∼ 4e, n = 6 ∼ 10) were water soluble, and their dissolution process in water was an endothermic process. Nonyl α-D-galactopyranoside (4d) showed excellent foaming ability and foam stability. Octyl α-D-galactopyranoside (4c) had the strongest emulsifying ability for toluene and nonyl α-D-galactopyranoside (4d) had the strongest emulsifying ability for rapeseed oil. The critical micelle concentration (CMC) values and surface tension at the CMC were decreasing with increasing alkyl chain length. Their standard free energy of adsorption (ΔGads) was more negative than their standard free energy of micellization (ΔGmic). The moisture-absorption abilities were weakening with increasing alkyl chain length. Alkyl α-D-galactopyranosides (4a ∼4f) were thermally stable below 280°C. Alkyl α-D-galactopyranosides (4c ∼4f) had the optical texture of the thermotropic liquid crystal smectic A phase.

Perspectives on Physicochemical Properties and Application of Biodiesel Blends

This paper analyzes a series of physicochemical properties of biodiesel blends, then explores the effect of biodiesel content on physicochemical properties of the blended fuel and the application prospects of biodiesel.

Prediction of Physicochemical Properties of Valine Ionic Liquids [Cnmim][Val] (n = 2, 3, 4, 5, 6) by Empirical Methods: 2

A new ionic liquid [C3mim][Val] (1-propyl-3-methylimidazolium valine) was synthesized and characterized by 1H NMR. To avoid the influence of trace water in the ionic liquid (IL), the standard addition method (SAM) was employed; the density and surface tension of the [C3mim][Val] were determined over the temperature range of 303.15–333.15 K (±0.05 K). The experimental density, surface tension, and parachor values at 298.15 K are in good agreement with that predicted by Tong et al. [J. Tong et al., Ind. Eng. Chem. Res.2011, 50, 2418–2423]. Based on the experimental data for [C3mim][Val], a series of physicochemical properties—the molecular volume (Vm), surface tension (γ), refractive index (nD), molar enthalpy of vaporization (ΔlgHm0), the thermal expansion coefficient (α) values, the standard molar entropy (S0), and the molar polarization (Rm)—for the homologue of [Cnmim][Val] (n = 2, 4, 5, 6) were estimated using the empirical methods. The estimated results are consistent with one of Tong’s estimations, in terms of the experimental data for [C2mim][Val].

Study on thermodynamic properties of a new air and water stable ionic liquid based on metal rhenium

A new air and water stable ionic liquid (IL) based on rhenium, N-butyl-pyridine perrhenate ([C4Py][ReO4]), was synthesized. The density and surface tension of the IL were determined over the temperature range of (293.15–343.15) K. In terms of the Glasser theory of IL and parachor, a series of physico-chemical properties: molecular volume, standard entropy, surface tension, and molar enthalpy of vaporization were predicted, respectively. According to the interstice model, the thermal expansion coefficient of the IL was calculated and in comparison with experimental value, it is in good agreement by 3.92%.

The Toxicokinetics and Toxicodynamics of Organophosphonates versus the Pharmacokinetics and Pharmacodynamics of Oxime Antidotes: Biological Consequences

This paper presents basic data on organophosphonate (OP) mechanisms of action, especially by toxicokinetic/toxicodynamic (TK/TD) process correlations. It is generally accepted that at least during onset of OP biological systems interaction, blood and tissue cholinesterase's inhibition represents OP exposure marker and initiating mechanisms for toxicodynamic effects, characteristic for cholinergic crisis. OP penetrability of various biological barriers conditioning TK characteristics are determined by a series of physico-chemical properties. Non-cholinergic effects, direct interactions with cellular structures and subsequent effects (excitotoxicity) triggered by cholinergic crisis are also briefly presented. Opposed to these OP TK/TD characteristics, the authors analysed the pharmacokinetic/pharmacodynamic (PK/PD) characteristics and their correlations for oximes, as basic OP antidotes, besides atropine and anticonvulsants. Phosphorilated cholinesterasis reactivators are mono or bispyridinium derivatives with quaternary ammonium atoms, high water solubility, ionized at physiological pH, distribution in extra-cellular space, very low digestive absorption and blood-brain barrier (BBB) penetrability. OP nerve gas acute toxicity is correlated with anti-acetylcholinesterase (AChE) activity and partition coefficient. The toxicity rank seems to be determined by lipophilicity, besides their specific AChE inhibitory property. It has the effect that acute toxicity is the resultant of a TD process closely linked and dependent in vivo upon molecular descriptors determinant for the TK process. For cholinesterasis reactivators, molecular and PK characteristics limit their effects, especially to the peripheral level. The absent or much reduced BBB penetrability allowed some researchers to suggest that reactivators' penetration and presence at central level are not necessary. The study of PK/PD correlations, molecular descriptors and biological membrane permeability of oximes can better define their antidotal effects mechanisms and, maybe, open a new perspective for field development.

Polymorphism of N-stearoylethanolamine: differential scanning calorimetric, vibrational spectroscopic (FTIR), and crystallographic studies

Based on a series of physicochemical properties (differential scanning calorimetry, powder X-ray crystallographic studies and Fourier-transform infra red spectroscopic analysis) determined for N-stearoylethanolamine (NSEA) (C18:0) at different temperatures, evidence has been given that this compound can exist in (at least) three polymorphic forms. Powder X-ray crystallography clearly demonstrates the presence of three distinct molecular packings at distinct temperatures while spectral changes in the vibrational spectra reveal that the geometry of the CH 2CO functional group of the molecule is affected during the polymorphic transitions. Rationalization of the thermal physicochemical behavior of NSEA in terms of molecular packing is also proposed. It supposes rearrangement of the hydrocarbon chains upon heating of the molecule.

Synergisms in binary surfactant mixtures

Significant correlations become apparent between synergisms of micelle formation in surfactant mixtures and a series of physico-chemical properties and applications. Examples are emulsifying, dispersing, wetting, flotation, washing and cleaning ability. As a result, the effect of a co-surfactant with respect to problems of application can be predicted by a few surface tension measurements only.