Hydrotalcite–PLGA composite nanoparticles for loading and delivery of danshensu

In vitro evaluation and in situ intestinal absorption characterisation of paeoniflorin nanoparticles in a rat model

Purpose: the aim of this study was to improve the stability and bioavailability of paeoniflorin (PF) by using nanoparticle encapsulation technology. Methods: paeoniflorin nanoparticles (PF NPs) were prepared with PLGA as the carrier using the compound emulsion method. The nanoparticles were characterised by using a Malvern laser particle sizer, transmission electron microscope (TEM), X-ray diffraction (XRD) analyser, and Fourier-transform infrared (FT-IR) spectrometry. The PF NPs were subjected to a series of stability investigations (such as for 4 °C storage stability, pH stability, and thermal stability), lyophilisation protection technology investigations, and in vitro release studies. Finally, the intestinal absorption properties of PF and PF NPs were studied by the in situ single-pass intestinal perfusion (SPIP) rat model, using the effective permeability coefficient (P eff) and the absorption rate constant (K a) as relevant indexes. Results: the prepared nanoparticles had a particle size of 105.0 nm with blue opalescent, rounded morphology, uniform size, good stability and slow release. We found that 4% alginate was the best lyoprotectant for the PF NPs. In the intestinal absorption experiments, P eff was higher for the PF NPs group compared with the original PF material drug group in all intestinal segments (P < 0.05), and the absorption rate constant K a increased with the increase in the drug concentration. Conclusion: the nanoparticles produced by this method have good stability and a slow-release effect; they can thus improve the absorption of PF in rat intestines, helping improve the stability and bioavailability of PF and enhancing its pharmacological effects.

Unveiling the Mechanism of Alleviating Ischemia Reperfusion Injury via a Layered Double Hydroxide-Based Nanozyme

Oxidative stress after ischemia reperfusion can cause irreversible brain damage. Thus, it is vital to timely consume excessive reactive oxygen species (ROS) and conduct molecular imaging monitoring on the brain injury site. However, previous studies have focused on how to scavenge ROS while ignoring the mechanism of relieving the reperfusion injury. Herein, we reported a layered double hydroxide (LDH)-based nanozyme (denoted as ALDzyme), which was fabricated by the confinement of astaxanthin (AST) with LDH. This ALDzyme can mimic natural enzymes, which include superoxide dismutase (SOD) and catalase (CAT). Furthermore, the SOD-like activity of ALDzyme is 16.3 times higher than that of CeO₂ (a typical ROS scavenger). Based on these enzyme-mimicking properties, this one-of-a-kind ALDzyme offers strong anti-oxidative properties as well as high biocompatibility. Importantly, this unique ALDzyme can establish an efficient magnetic resonance imaging platform, thus guiding the in vivo details. As a result, the infarct area can be reduced by 77% after reperfusion therapy, and the neurological impairment score can be lowered from 3-4 to 0-1. Density functional theory computations can reveal more about the mechanism of this ALDzyme's significant ROS consumption. These findings provide a method for unraveling the neuroprotection application process in ischemia reperfusion injury using an LDH-based nanozyme as a remedial nanoplatform.

Biomaterials Based on Organic Polymers and Layered Double Hydroxides Nanocomposites: Drug Delivery and Tissue Engineering

The development of biomaterials has a substantial role in pharmaceutical and medical strategies for the enhancement of life quality. This review work focused on versatile biomaterials based on nanocomposites comprising organic polymers and a class of layered inorganic nanoparticles, aiming for drug delivery (oral, transdermal, and ocular delivery) and tissue engineering (skin and bone therapies). Layered double hydroxides (LDHs) are 2D nanomaterials that can intercalate anionic bioactive species between the layers. The layers can hold metal cations that confer intrinsic biological activity to LDHs as well as biocompatibility. The intercalation of bioactive species between the layers allows the formation of drug delivery systems with elevated loading capacity and modified release profiles promoted by ion exchange and/or solubilization. The capacity of tissue integration, antigenicity, and stimulation of collagen formation, among other beneficial characteristics of LDH, have been observed by in vivo assays. The association between the properties of biocompatible polymers and LDH-drug nanohybrids produces multifunctional nanocomposites compatible with living matter. Such nanocomposites are stimuli-responsive, show appropriate mechanical properties, and can be prepared by creative methods that allow a fine-tuning of drug release. They are processed in the end form of films, beads, gels, monoliths etc., to reach orientated therapeutic applications. Several studies attest to the higher performance of polymer/LDH-drug nanocomposite compared to the LDH-drug hybrid or the free drug.

Surface modification of two-dimensional layered double hydroxide nanoparticles with biopolymers for biomedical applications

Layered double hydroxides (LDHs) are appealing nanomaterials for (bio)medical applications and their potential is threefold. One can gain advantage of the structure of LDH frame (i.e., layered morphology), anion exchanging property towards drugs with acidic character and tendency for facile surface modification with biopolymers. This review focuses on the third aspect, as it is necessary to evaluate the advantages of polymer adsorption on LDH surfaces. Beside the short discussion on fundamental and structural features of LDHs, LDH-biopolymer interactions will be classified in terms of the effect on the colloidal stability of the dispersions. Thereafter, an overview on the biocompatibility and biomedical applications of LDH-biopolymer composite materials will be given. Finally, the advances made in the field will be summarized and future research directions will be suggested.

Engineering atorvastatin loaded Mg-Mn/LDH nanoparticles and their composite with PLGA for bone tissue applications

The impact of mixing method in conventional co-precipitation synthesis of layered double hydroxides (LDHs), on particle size, size distribution and drug loading capacity is reported. Synthesis of Mg (II)/Mn (III)-LDH nano-platelets was performed at constant pH using three different mixing systems, magnetic stirrer, mechanical mixer, and homogenizer at ambient temperature and a fixed Mg/Mn ratio of 3/1. The LDH characterization results showed that mechanical mixing and homogenization lead to production of very fine LDH nano-platelets (about 90-140 nm), with narrow particle size distribution. Amount of the intercalated drug was determined as about 60% and showed a significant increase in loading capacity of the LDH through homogenization and mechanical mixing compared to that of the magnetic stirring (about 35%). Our results also showed that in LDH preparation via co-precipitation, the mixing system plays a more influential role in particle size, size distribution, and drug loading control, than the mixing speed of each system. Drug loaded-LDH/PLGA composites were prepared via electrospinning to afford a bioactive/osteoinductive scaffold. A remarkable degree of cell viability on the scaffolds (drug-loaded-LDH/PLGA composite) was confirmed using MTT assay. Osteogenic differentiation of human ADMSCs, as shown by alkaline phosphatase activity and Alizarin Red staining assays, indicated that the scaffold with 5% drug loaded LDH(Mn-Mg-LDH/PLGA/AT5%) induced a remarkably higher level of the markers compared to the PLGA scaffold and therefore, it could be a valuable candidate for bone tissue engineering applications.