Polydopamine Nanobowl-Armoured Perfluorocarbon Emulsions: Tracking Thermal- and Photothermal-Induced Phase Change through Neutron Scattering

Anisotropic polydopamine nanobowls (PDA NBs) show significant promise in biomedicine, distinguished by their unique optical properties and superior cellular uptake compared to spherical nanoparticles. This study presents a novel approach for creating multistimuli-activated PDA NB-armored emulsions, encapsulating perfluorohexane (NB-H) and perfluoropentane (NB-P) cores, with applications in controlled delivery and ultrasound imaging. Thermal and photothermal activation induced distinct responses in the emulsions, as evidenced by optical microscopy and thermogravimetric analysis. For the first time, neutron scattering techniques (SANS and USANS) under contrast matching conditions are applied to investigate these materials, revealing detailed droplet and microbubble structures and phase transition dynamics. These results show that NB-H droplets resist phase change under direct heating, whereas NB-P droplets respond more readily, exhibiting significant bubble formation. During photothermal activation with short near-infrared (NIR) exposure (15 min at 400 mW cm-2), SANS and USANS analyses reveal varying degrees of phase transition, proving this activation method to be more effective than direct heating. Importantly, NB-H and NB-P droplets have excellent ultrasound contrast enhancement and biocompatibility, indicating their potential for contrast-enhanced ultrasound imaging, theranostics, and photothermal applications. This comprehensive study advances the understanding of multifunctional colloidal materials in biomedicine, contributing essential knowledge to this rapidly evolving field.

Polydopamine Nanomaterials for Overcoming Current Challenges in Cancer Treatment

In efforts to overcome current challenges in cancer treatment, multifunctional nanoparticles are attracting growing interest, including nanoparticles made with polydopamine (PDA). PDA is a nature-inspired polymer with a dark brown color. It has excellent biocompatibility and is biodegradable, offering a range of extraordinary inherent advantages. These include excellent drug loading capability, photothermal conversion efficiency, and adhesive properties. Though the mechanism of dopamine polymerization remains unclear, PDA has demonstrated exceptional flexibility in engineering desired morphology and size, easy and straightforward functionalization, etc. Moreover, it offers enormous potential for designing multifunctional nanomaterials for innovative approaches in cancer treatment. The aim of this work is to review studies on PDA, where the potential to develop multifunctional nanomaterials with applications in photothermal therapy has been demonstrated. Future prospects of PDA for developing applications in enhancing radiotherapy and/or immunotherapy, including for image-guided drug delivery to boost therapeutic efficacy and minimal side effects, are presented.

Luminescence encoding of polymer microbeads with organic dyes and semiconductor quantum dots during polymerization

Luminescence-encoded microbeads are important tools for many applications in the life and material sciences that utilize luminescence detection as well as multiplexing and barcoding strategies. The preparation of such beads often involves the staining of premanufactured beads with molecular luminophores using simple swelling procedures or surface functionalization with layer-by-layer (LbL) techniques. Alternatively, these luminophores are sterically incorporated during the polymerization reaction yielding the polymer beads. The favorable optical properties of semiconductor quantum dots (QDs), which present broadly excitable, size-tunable, narrow emission bands and low photobleaching sensitivity, triggered the preparation of beads stained with QDs. However, the colloidal nature and the surface chemistry of these QDs, which largely controls their luminescence properties, introduce new challenges to bead encoding that have been barely systematically assessed. To establish a straightforward approach for the bead encoding with QDs with minimized loss in luminescence, we systematically assessed the incorporation of oleic acid/oleylamine-stabilized CdSe/CdS-core/shell-QDs into 0.5-2.5 µm-sized polystyrene (PS) microspheres by a simple dispersion polymerization synthesis that was first optimized with the organic dye Nile Red. Parameters addressed for the preparation of luminophore-encoded beads include the use of a polymer-compatible ligand such as benzyldimethyloctadecylammonium chloride (OBDAC) for the QDs, and crosslinking to prevent luminophore leakage. The physico-chemical and optical properties of the resulting beads were investigated with electron microscopy, dynamic light scattering, optical spectroscopy, and fluorescence microscopy. Particle size distribution, fluorescence quantum yield of the encapsulated QDs, and QD leaking stability were used as measures for bead quality. The derived optimized bead encoding procedure enables the reproducible preparation of bright PS microbeads encoded with organic dyes as well as with CdSe/CdS-QDs. Although these beads show a reduced photoluminescence quantum yield compared to the initially very strongly luminescent QDs, with values of about 35%, their photoluminescence quantum yield is nevertheless still moderate.

Microparticles, Microspheres, and Microcapsules for Advanced Drug Delivery

Microparticles, microspheres, and microcapsules are widely used constituents of multiparticulate drug delivery systems, offering both therapeutic and technological advantages. Microparticles are generally in the 1–1000 µm size range, serve as multiunit drug delivery systems with well-defined physiological and pharmacokinetic benefits in order to improve the effectiveness, tolerability, and patient compliance. This paper reviews their evolution, significance, and formulation factors (excipients and procedures), as well as their most important practical applications (inhaled insulin, liposomal preparations). The article presents the most important structures of microparticles (microspheres, microcapsules, coated pellets, etc.), interpreted with microscopic images too. The most significant production processes (spray drying, extrusion, coacervation, freeze-drying, microfluidics), the drug release mechanisms, and the commonly used excipients, the characterization, and the novel drug delivery systems (microbubbles, microsponges), as well as the preparations used in therapy are discussed in detail.