Fabrication of hollow porous PLGA microspheres using sucrose for controlled dual delivery of dexamethasone and BMP2

Hollow Nanomaterials in Advanced Drug Delivery Systems: From Single- to Multiple Shells

Hollow-structured nanomaterials (HSNMs) have attracted increased interest in biomedical fields, owing to their excellent potential as drug delivery systems (DDSs) for clinical applications. Among HSNMs, hollow multi-shelled structures (HoMSs) exhibit properties such as high loading capacity, sequential drug release, and multi-functionalized modification and represent a new class of nanoplatforms for clinical applications. The remarkable properties of HoMS-based DDS can simultaneously satisfy and enhance DDSs for delivering small molecular drugs (e.g., antibiotics, chemotherapy drugs, and imaging agents) and macromolecular drugs (e.g., protein/peptide- and nucleic acid-based drugs). First, the latest research advances in delivering small molecular drugs are summarized and highlight the inherent advantages of HoMS-based DDSs for small molecular drug targeting, combining continuous therapeutic drug delivery and theranostics to optimize the clinical benefit. Meanwhile, the macromolecular drugs DDSs are in the initial development stage and currently offer limited delivery modes. There is a growing need to analyze the deficiency of other HSNMs and integrate the advantages of HSNMs, providing solutions for the safe, stable, and cascade delivery of macromolecular drugs to meet vast treatment requirements. Therefore, the latest advances in HoMS-based DDSs are comprehensively reviewed, mainly focusing on the characteristics, research progress by drug category, and future research prospects.

Hollow structures as drug carriers: Recognition, response, and release

Hollow structures have demonstrated great potential in drug delivery owing to their privileged structure, such as high surface-to-volume ratio, low density, large cavities, and hierarchical pores. In this review, we provide a comprehensive overview of hollow structured materials applied in targeting recognition, smart response, and drug release, and we have addressed the possible chemical factors and reactions in these three processes. The advantages of hollow nanostructures are summarized as follows: hollow cavity contributes to large loading capacity; a tailored structure helps controllable drug release; variable compounds adapt to flexible application; surface modification facilitates smart responsive release. Especially, because the multiple physical barriers and chemical interactions can be induced by multishells, hollow multishelled structure is considered as a promising material with unique loading and releasing properties. Finally, we conclude this review with some perspectives on the future research and development of the hollow structures as drug carriers.

Metal-Based Nanostructures/PLGA Nanocomposites: Antimicrobial Activity, Cytotoxicity, and Their Biomedical Applications

Among the different synthetic polymers developed for biomedical applications, poly(lactic-co-glycolic acid) (PLGA) has attracted considerable attention because of its excellent biocompatibility and biodegradability. Nanocomposites based on PLGA and metal-based nanostructures (MNSs) have been employed extensively as an efficient strategy to improve the structural and functional properties of PLGA polymer. The MNSs have been used to impart new properties to PLGA, such as antimicrobial properties and labeling. In the present review, the different strategies available for the fabrication of MNS/PLGA nanocomposites and their applications in the biomedical field will be discussed, beginning with a description of the preparation routes, antimicrobial activity, and cytotoxicity concerns of MNS/PLGA nanocomposites. The biomedical applications of these nanocomposites, such as carriers and scaffolds in tissue regeneration and other therapies are subsequently reviewed. In addition, the potential advantages of using MNS/PLGA nanocomposites in treatment illnesses are analyzed based on in vitro and in vivo studies, to support the potential of these nanocomposites in future research in the biomedical field.

Dual delivery nanosystem for biomolecules. Formulation, characterization, and in vitro release

Because of the biocompatible and biodegradable properties of poly (lactic-co-glycolic acid) (PLGA), nanoparticles (NPs) based on this polymer have been widely studied for drug/biomolecule delivery and long-term sustained-release. In this work, two different formulation methods for lysozyme-loaded PLGA NPs have been developed and optimized based on the double-emulsion (water/oil/water, W/O/W) solvent evaporation technique. They differ mainly in the phase in which the surfactant (Pluronic^® F68) is added: water (W-F68) and oil (O-F68). The colloidal properties of these systems (morphology by SEM and STEM, hydrodynamic size by DLS and NTA, electrophoretic mobility, temporal stability in different media, protein encapsulation, release, and bioactivity) have been analyzed. The interaction surfactant-protein depending on the formulation procedure has been characterized by surface tension and dilatational rheology. Finally, cellular uptake by human mesenchymal stromal cells and cytotoxicity for both systems have been analyzed. Spherical hard NPs are made by the two methods However, in one case, they are monodisperse with diameters of around 120nm (O-F68), and in the other case, a polydisperse system of NPs with diameters between 100 and 500nm is found (W-F68). Protein encapsulation efficiency, release and bioactivity are maintained better by the W-F68 formulation method. This multimodal system is found to be a promising "dual delivery" system for encapsulating hydrophilic proteins with strong biological activity at the cell-surface and cytoplasmic levels.