The versatile biomedical applications of bismuth-based nanoparticles and composites: therapeutic, diagnostic, biosensing, and regenerative properties.

Studies of nanosized forms of bismuth (Bi)-containing materials have recently expanded from optical, chemical, electronic, and engineering fields towards biomedicine, as a result of their safety, cost-effective fabrication processes, large surface area, high stability, and high versatility in terms of shape, size, and porosity. Bi, as a nontoxic and inexpensive diamagnetic heavy metal, has been used for the fabrication of various nanoparticles (NPs) with unique structural, physicochemical, and compositional features to combine various properties, such as a favourably high X-ray attenuation coefficient and near-infrared (NIR) absorbance, excellent light-to-heat conversion efficiency, and a long circulation half-life. These features have rendered bismuth-containing nanoparticles (BiNPs) with desirable performance for combined cancer therapy, photothermal and radiation therapy (RT), multimodal imaging, theranostics, drug delivery, biosensing, and tissue engineering. Bismuth oxyhalides (BiOx, where X is Cl, Br or I) and bismuth chalcogenides, including bismuth oxide, bismuth sulfide, bismuth selenide, and bismuth telluride, have been heavily investigated for therapeutic purposes. The pharmacokinetics of these BiNPs can be easily improved via the facile modification of their surfaces with biocompatible polymers and proteins, resulting in enhanced colloidal stability, extended blood circulation, and reduced toxicity. Desirable antibacterial effects, bone regeneration potential, and tumor growth suppression under NIR laser radiation are the main biomedical research areas involving BiNPs that have opened up a new paradigm for their future clinical translation. This review emphasizes the synthesis and state-of-the-art progress related to the biomedical applications of BiNPs with different structures, sizes, and compositions. Furthermore, a comprehensive discussion focusing on challenges and future opportunities is presented.

Preparation, optimization, and in-vitro characterization of α-tocopherol-loaded solid lipid nanoparticles (SLNs).

Objective: The main scope of present investigation was preparation and physicochemical characterization of solid lipid nanoparticles (SLNs) loaded by α-tocopherol acetate (ATA).Methods: ATA-loaded nanoparticles were prepared by solvent injection-homogenization technique using stearic acid as the solid lipid, phosphatidylcholine as the stabilizer and finally coated by chitosan with the aim of increasing z-potential and also having a more stable nano-formulation. Then, characterization of SLNs has been conducted using dynamic light scattering (DLS), zeta potential measurement, Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC).Results: Nanoparticles with average sizes of 175 ± 15 nm and zeta potential of +35 ± 2.5 mV were obtained. An excellent drug entrapment efficiency of 90.58 ± 1.38% was obtained with a no-burst slow release up to about 10 days tested. The final plateau of release of ATA from nanoparticulate system within 216 h was 61.13 ± 0.13% which was approached in about 150 h. Physical stability studies showed that the ATA nano-formulation remained stable with slight increase in mean particle size and polydispersity index over a 3-month period in refrigerated temperature. Considering both FTIR and DSC analysis, it can be concluded that there is no new band formation between materials and ATA in our nano-formulation. Particle sizes obtained using AFM images are in a good agreement to those established from the DLS analysis.Conclusion: These data showed a promising delivery system for vitamin E based on SLN platform.