Magnetic nanoparticles-loaded PLA/PEG microspheres as drug carriers

Kinetics of Flavonoid Degradation and Controlled Release from Functionalized Magnetic Nanoparticles

Flavonoids are naturally occurring antioxidants that have been shown to protect cell membranes from oxidative stress and have a potential use in photodynamic cancer treatment. However, they degrade at physiological pH values, which is often neglected in drug release studies. Kinetic study of flavonoid oxidation can help to understand the mechanism of degradation and to correctly analyze flavonoid release data. Additionally, the incorporation of flavonoids into magnetic nanocarriers can be utilized to mitigate degradation and overcome their low solubility, while the release can be controlled using magnetic fields (MFs). An approach that combines alternating least squares (ALS) and multilinear regression to consider flavonoid autoxidation in release studies is presented. This approach can be used in general cases to account for the degradation of unstable drugs released from nanoparticles. The oxidation of quercetin, myricetin (MCE), and myricitrin (MCI) was studied in PBS buffer (pH = 7.4) using UV-vis spectrophotometry. ALS was used to determine the kinetic profiles and characteristic spectra, which were used to analyze UV-vis data of release from functionalized magnetic nanoparticles (MNPs). MNPs were selected for their unique magnetic properties, which can be exploited for both targeted drug delivery and control over the drug release. MNPs were prepared and characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, superconducting quantum interference device magnetometer, and electrophoretic mobility measurements. Autoxidation of all three flavonoids follows a two-step first-order kinetic model. MCE showed the fastest degradation, while the oxidation of MCI was the slowest. The flavonoids were successfully loaded into the prepared MNPs, and the drug release was described by the first-order and Korsmeyer-Peppas models. External MFs were utilized to control the release mechanism and the cumulative mass of the flavonoids released.

Progress in the application of sustained-release drug microspheres in tissue engineering

Sustained-release drug-loaded microspheres provide a long-acting sustained release, with targeted and other effects. There are many types of sustained-release drug microspheres and various preparation methods, and they are easy to operate. For these reasons, they have attracted widespread interest and are widely used in tissue engineering and other fields. In this paper, we provide a systematic review of the application of sustained-release drug microspheres in tissue engineering. First, we introduce this new type of drug delivery system (sustained-release drug carriers), describe the types of sustained-release drug microspheres, and summarize the characteristics of different microspheres. Second, we summarize the preparation methods of sustained-release drug microspheres and summarize the materials required for preparing microspheres. Third, various applications of sustained-release drug microspheres in tissue engineering are summarized. Finally, we summarize the shortcomings and discuss future prospects in the development of sustained-release drug microspheres. The purpose of this paper was to provide a further systematic understanding of the application of sustained-release drug microspheres in tissue engineering for the personnel engaged in related fields and to provide inspiration and new ideas for studies in related fields.

Understanding the hydrolysis mechanism on segments and aggregate structures: Corrosion-tailored poly (lactic acid) deriving copolymers with δ-valerolactone

Poly (L-lactic acid) (PLLA) based copolymers modified with δ-valerolactone (DVL) through random copolymerization (PVLA-R) and block copolymerization (PVLA-B) with various DVL content were prepared to investigate their degradation regulation and mechanism. Chemical structure, thermal properties, hydrophilicity, crystallization as well as the crystal defects of the obtained copolymers were respectively confirmed. Degradation regulation of both PVLA-R and PVLA-B, such molecular weight and pH value changes of PLLA based copolymers were investigated via vitro degradation method. In order to further explore the degradation principle of the two copolymers, their degradation residues at different stages were systematically studied. The addition and increasing content of DVL disturbs the regularity of original PLLA molecular structure, resulting in accelerating degradation of copolymers. Compared with amorphous region, the crystalline region of both two copolymers has better corrosion resistance, which could be confirmed by increased melting point and crystallinity of both PVLA-R and PVLA-B degradation residues. PVLA-B copolymers show relatively superior degradation resistance mainly due to their higher molecular weight, crystallinity and hydrophobic index than PVLA-R copolymers.

Pathways to Green Perspectives: Production and Characterization of Polylactide (PLA) Nanocomposites Filled with Superparamagnetic Magnetite Nanoparticles

In the category of biopolymers, polylactide or polylactic acid (PLA) is one of the most promising candidates considered for future developments, as it is not only biodegradable under industrial composting conditions, but it is produced from renewable natural resources. The modification of PLA through the addition of nanofillers is considered as a modern approach to improve its main characteristic features (mechanical, thermal, barrier, etc.) and to obtain specific end-use properties. Iron oxide nanoparticles (NPs) of low dimension (10–20 nm) such as magnetite (Fe₃O₄), exhibit strong magnetization in magnetic field, are biocompatible and show low toxicity, and can be considered in the production of polymer nanocomposites requiring superparamagnetic properties. Accordingly, PLA was mixed by melt-compounding with 4–16 wt.% magnetite NPs. Surface treatment of NPs with a reactive polymethylhydrogensiloxane (MHX) was investigated to render the nanofiller water repellent, less sensitive to moisture and to reduce the catalytic effects at high temperature of iron (from magnetite) on PLA macromolecular chains. The characterization of nanocomposites was focused on the differences of the rheology and morphology, modification, and improvements in the thermal properties using surface treated NPs, while the superparamagnetic behavior was confirmed by VSM (vibrating sample magnetometer) measurements. The PLA−magnetite nanocomposites had strong magnetization properties at low magnetic field (values close to 70% of M_max at H = 0.2 T), while the maximum magnetic signal (M_max) was mainly determined by the loading of the nanofiller, without any significant differences linked to the surface treatment of MNPs. These bionanocomposites showing superparamagnetic properties, close to zero magnetic remanence, and coercivity, can be further produced at a larger scale by melt-compounding and can be designed for special end-use applications, going from biomedical to technical areas.

A Full Set of In Vitro Assays in Chitosan/Tween 80 Microspheres Loaded with Magnetite Nanoparticles

Microspheres have been proposed for different medical applications, such as the delivery of therapeutic proteins. The first step, before evaluating the functionality of a protein delivery system, is to evaluate their biological safety. In this work, we developed chitosan/Tween 80 microspheres loaded with magnetite nanoparticles and evaluated cell damage. The formation and physical-chemical properties of the microspheres were determined by FT-IR, Raman, thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS), dynamic light scattering (DLS), and SEM. Cell damage was evaluated by a full set of in vitro assays using a non-cancerous cell line, human erythrocytes, and human lymphocytes. At the same time, to know if these microspheres can load proteins over their surface, bovine serum albumin (BSA) immobilization was measured. Results showed 7 nm magnetite nanoparticles loaded into chitosan/Tween 80 microspheres with average sizes of 1.431 µm. At concentrations from 1 to 100 µg/mL, there was no evidence of changes in mitochondrial metabolism, cell morphology, membrane rupture, cell cycle, nor sister chromatid exchange formation. For each microgram of microspheres 1.8 µg of BSA was immobilized. The result provides the fundamental understanding of the in vitro biological behavior, and safety, of developed microspheres. Additionally, this set of assays can be helpful for researchers to evaluate different nano and microparticles.

In vivo effect of magnetic microspheres loaded with E2-a in the treatment of alveolar echinococcosis

The alveolar echinococcosis of human is a severe helminthic disease caused by the larva of Echinococcus multilocularis tapeworms. Novel compounds or therapy strategies for the treatment of alveolar echinococcosis are urgently needed due to the limitation of the widely used albendazole. Magnetic microspheres as drug carriers in magnetically targeted therapy of tumor have gained growing interests advantaged by delivering the drug to the aimed site, achieving localized therapeutic effect effectively under the influence of an external magnetic field. In this study, we formulated magnetic microspheres loaded with E2-a (PLGA-Fe-E2-a) and identified the activity in E. multilocularis-infected mice which infected with 3,000 protoscoleces intraperitoneally. Compared with the untreated control, with the help of a magnet, there was a significant reduction in parasite burden with PLGA-Fe-E2-a treatment and similar reduction observed with albendazole. PLGA-Fe-E2-a treatment group also showed a significant increase in the IFN-γ level and impaired morphological and ultrastructural alterations. Most importantly, one-third concentrations of E2-a from PLGA-Fe-E2 based on the release profile of E2-a was equally effective in inhibiting metacestode growth as E2-a treated group, supporting efficacy and bioavailability of a drug. It will be an alternative treatment for alveolar echinococcosis using magnetic microspheres as drug carriers.

Preparation of BMP-2 loaded MPEG-PCL microspheres and evaluation of their bone repair properties

Autologous or allogeneic bone grafts are common methods to treat bone defects. Bone tissue engineering combining carrier material with the active factor can induce a generation of new bone at the bone defect site. However, its clinical application is restricted by the limited donors, the high morbidity at the donor site, the low activity in vivo, and dose-independent adverse effect. To overcome the limitations of traditional therapies, it is urgent to find and develop a repair material that can replace natural bones. Hence, we designed and prepared suitable MPEG-PCL microspheres loaded bone morphogenetic protein-2 (BMP-2/MPEG-PCL-MS) to effectively solve the problem mentioned above, prolong its reaction time at the targeted site, and avoid the pain of patients caused by frequent administration. The physicochemical properties and in vitro release behaviors were good. The microspheres showed high biocompatibility and strongly induced osteogenesis in vivo. BMP-2/MPEG-PCL-MS has been proven to exert sustained-release in vivo and maintain the inherent BMP-2 activity. They can be directly injected into the bone defect site, or implanted to a large bone defect site together with stent material to exert therapeutic effects. Hence, this smart drug delivery system has promising potential for clinical applications and provides a well-controlled design for combination of tissue engineering and pharmaceutics for further exploration.

MRI Detectable Polymer Microspheres Embedded With Magnetic Ferrite Nanoclusters For Embolization: In Vitro And In Vivo Evaluation

OBJECTIVE

The objective of this study was to develop magnetic embolic microspheres that could be visualized by clinical magnetic resonance imaging (MRI) scanners aiming to improve the efficiency and safety of embolotherapy.

METHODS AND DISCUSSION

Magnetic ferrite nanoclusters (FNs) were synthesized with microwave-assisted solvothermal method, and their morphology, particle size, crystalline structure, magnetic properties as well as T2 relaxivity were characterized to confirm the feasibility of FNs as an MRI probe. Magnetic polymer microspheres (FNMs) were then produced by inverse suspension polymerization with FNs embedded inside. The physicochemical and mechanical properties (including morphology, particle size, infrared spectra, elasticity, etc.) of FNMs were investigated, and the magnetic properties and MRI detectable properties of FNMs were also assayed by vibrating sample magnetometer and MRI scanners. Favorable biocompatibility and long-term MRI detectability of FNMs were then studied in mice by subcutaneous injection. FNMs were further used to embolize rabbits' kidneys to evaluate the embolic property and detectability by MRI.

CONCLUSION

FNMs could serve as a promising MRI-visualized embolic material for embolotherapy in the future.

Nanobiomaterials Used in Cancer Therapy: An Up-To-Date Overview

The disadvantages that come with traditional cancer treatments, such as chemotherapy and radiotherapy, generated a research shift toward nanotechnology. However, even with the important advancements regarding cancer therapy, there are still serious stepping stones that need to be addressed. The use of both nanotechnology and nanomedicine has generated significant improvements in nano-sized materials development and their use as therapeutic, diagnosis, and imaging agents. The biological barriers that come from the healthy body, as well from the tumorous sites, are important parameters that need to be taken into consideration when designing drug delivery systems. There are several aspects of extreme importance such as the tumor microenvironment and vasculature, the reticuloendothelial system, the blood-brain barrier, the blood-tumor barrier, and the renal system. In order to achieve an effective system for cancer therapy, several characteristics of the nanoparticles have been outlined. Moreover, this review has also focused on the different types of nanoparticles that have been studied over the years as potential candidates for cancer therapy.

Biocompatible HA@Fe3 O4 @N-CDs hybrids for detecting and absorbing lead ion

The trinary hydroxyapatite@Fe₃ O₄ @N-doped carbon dots (HA@Fe₃ O₄ @N-CDs) hybrids were prepared by one-pot hydrothermal approach and utilized to detect and remove lead ion from aqueous solution. The structures and morphologies of as-obtained nanorod-like HA@Fe₃ O₄ @N-CDs hybrids were characterized by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy measurements. These HA@Fe₃ O₄ @N-CDs hybrids possess good magnetism by magnetic hysteresis test and multi-colored fluorescence by the CLSM measurement. Furthermore, the as-obtained hybrids display excellent biocompatibility by MTT assay. Importantly, the trinary magnetic HA@Fe₃ O₄ @N-CDs hybrids as a green detector and adsorbent of Pb²⁺ were investigated. The influence of the different pH, the concentration of heavy metal, and the maximum adsorption capacity on removal efficiency was measured in detail. The maximum Pb²⁺ adsorption capacity on HA@Fe₃ O₄ @N-CDs hybrids is 450 mg/g. The kinetic mechanism was a pseudo-second order model, and the isotherm data was fitted well by the Langmuir isotherm and Freundlich model. Hence, the nanorod-like HA@Fe₃ O₄ @N-CDs hybrids could be a multifunctional material with significant potential applications in heavy metal detection and adsorption, bone tissue regeneration, magnetic therapy, and biomedicine. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2019.

Magnetic nanoparticles in cancer diagnosis, drug delivery and treatment

In recent years, magnetic nanoparticles (MNPs) have demonstrated marked progress in the field of oncology. General nanoparticles are widely used in tumor targeting, and the intrinsic magnetic property of MNPs makes them the most promising nanomaterial to be used as contrast agents for magnetic resonance imaging (MRI) and induced magnetic hyperthermia. The properties of MNPs are fully exploited when they are used as drug delivery agents, wherein drugs may be targeted to the desired specific location in vivo by application of an external magnetic field. Early diagnosis of cancer may be achieved by MRI, therefore, individualized treatment may be combined with MRI, so as to achieve the precise definition and appropriate treatment. In the present review, research on MNPs in cancer diagnosis, drug delivery and treatment has been summarized. Furthermore, the future perspectives and challenges of MNPs in the field of oncology are also discussed.

Polylactic acid (PLA) controlled delivery carriers for biomedical applications

Polylactic acid (PLA) and its copolymers have a long history of safety in humans and an extensive range of applications. PLA is biocompatible, biodegradable by hydrolysis and enzymatic activity, has a large range of mechanical and physical properties that can be engineered appropriately to suit multiple applications, and has low immunogenicity. Formulations containing PLA have also been Food and Drug Administration (FDA)-approved for multiple applications making PLA suitable for expedited clinical translatability. These biomaterials can be fashioned into sutures, scaffolds, cell carriers, drug delivery systems, and a myriad of fabrications. PLA has been the focus of a multitude of preclinical and clinical testing. Three-dimensional printing has expanded the possibilities of biomedical engineering and has enabled the fabrication of a myriad of platforms for an extensive variety of applications. PLA has been widely used as temporary extracellular matrices in tissue engineering. At the other end of the spectrum, PLA's application as drug-loaded nanoparticle drug carriers, such as liposomes, polymeric nanoparticles, dendrimers, and micelles, can encapsulate otherwise toxic hydrophobic anti-tumor drugs and evade systemic toxicities. The clinical translation of these technologies from preclinical experimental settings is an ever-evolving field with incremental advancements. In this review, some of the biomedical applications of PLA and its copolymers are highlighted and briefly summarized.

Magnetic-responsive microparticles with customized porosity for drug delivery

One step engineering of drug-loaded magnetic porous particles for controlled release and targeting.