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Advanced Topics in Gold Nanoparticles: Biomedical Applications
Published in Jay L. Nadeau, Introduction to Experimental Biophysics, 2017
The first step in the synthesis is the fabrication of the Au particles capped with a free carboxylate group for conjugating Dox. In this example, we fabricated Au–tiopronin (Figure 13.4a). Tiopronin is FDA-approved as a drug to treat cystinuria, so its use in the formulation is expected to be nontoxic and to pose few regulatory problems. This is an important consideration, since some capping groups for Au nanoparticles, such as cetyltrimethylammonium bromide (CTAB), are highly toxic. Tiopronin is negatively charged at physiological pH, as confirmed by zeta potential measurements (−16.79 ± 1.94 mV). A size distribution of 2.7 ± 0.5 nm was obtained from electron microscopy, giving a mean number of atoms per particle of 169 (Figure 13.4b). Fourier transform infrared (FTIR) spectra (see Chapter 16) show stretches at 3300 nm (O=H of carboxylic acids) and 1700 nm (C=O of carboxylic acids), which further confirmed the successful synthesis of the nanoparticles (Figure 13.4c). By dissolving 33 mg of gold–tiopronin particles in 1 L of H2O, the concentration was measured to be 16.6 ppm by flame atomic absorption spectroscopy. Therefore, 50.3% w/w of each nanoparticle was the gold core and the 49.7% w/w was the tiopronin ligands, giving a chemical formula of Au169Tiopronin207. Absorbance spectroscopy showed no distinct peak at any wavelength, consistent with subplasmonic particles. The particles were fluorescent in the near-IR range with a quantum yield of approximately 1.62 × 10−3 (Figure 13.4d). Particles were also characterized by electron microscopy with selected area electron diffraction (SAED) and energy-dispersive x-ray spectroscopy (EDS).
Polymeric biomaterials for wound healing applications: a comprehensive review
Published in Journal of Biomaterials Science, Polymer Edition, 2022
Ahmed Olanrewaju Ijaola, Damilola O. Akamo, Fouad Damiri, Cletus John Akisin, Emmanuel Anuoluwa Bamidele, Emmanuel Gboyega Ajiboye, Mohammed Berrada, Victor Onyebuchukwu Onyenokwe, Shang-You Yang, Eylem Asmatulu
Recently, Valachova et al. [131] developed composite biomembranes loaded with tiopronin or captopril for chronic wound-healing application. These novel biomembranes consist of chitosan and hyaluronan with captopril/tiopronin as an anti-inflammatory agent. The wound-healing capability of the CS/HA/tiopronin or CS/HA/captopril membranes was investigated using skin wounds of ischemic rabbits. It was determined that either of these biomembranes accelerated the healing of wounds compared to animals treated with CS/HA membranes alone and to untreated animals. However, the incorporation of tiopronin and captopril at higher concentrations reduced the degradation rate of HA. In a different study, Savitskaya et al. [132] fabricated a biocomposite consisting of Bacillus subtilis (BS) cells and bacterial cellulose (BC) gel-film. Here, 1010 viable cells per 1 g of the film wet mass were immobilized on the biocomposite. These immobilized BS cells showed high bactericidal activity against pathogens commonly in the wound area, including Staphylococcus aureus, Staphylococcus epidermis, Escherichia coli, and Pseudomonas aeruginosa. Specifically, the antimicrobial capability of BS is improved by the lytic enzymes, which were actively lysing the cells of gram-negative and gram-positive bacteria. Overall, with the BC/BS biocomposite, it took seven days for total wound closure to take place. The material has the potential to be used as a universal wound dressing and sanitary-hygienic solution.