Historical review of the use of silver in the treatment of burns. I. Early uses

Silver(I) complexes of types [Ag(X){E(CH₂C₆H₄Me-2)₂}] [E = S, X  = CF₃SO₃ (1), NO₃ (2), ClO₄ (3); E = Se, X  = CF₃SO₃ (4), NO₃ (5), ClO₄ (6)] and [Ag(X){E(CH₂C₆H₄Me-2)₂}₂] [X = CF₃SO₃, E = S (7), Se (8); X  = ClO₄, E = S (9), Se (10)] were prepared by reacting the diorganochalcogenides (2-MeC₆H₄CH₂)₂E [E = S (L¹), Se (L²)] with the appropriate silver(I) salt in a 1:1 and a 2:1  molar ratio, respectively. The ligands and the Ag(I) complexes were characterized by multinuclear NMR spectroscopy (¹H, ¹³C{¹H}, ¹⁹F{¹H}, ⁷⁷Se{¹H}, as appropriate), ESI+ mass spectrometry, elemental analysis and IR spectroscopy. The crystal and molecular structures of the ligand L¹ and the complexes 2, 5, 7, 8 and 9 were determined by single-crystal X-ray diffraction. The molar conductivity of the reported metal complexes showed their behaviour as 1:1 electrolytes in solution, while in solid state the inorganic anionic ligand is coordinated to silver by OAg bonds. Preliminary results showed that the silver(I) complexes bearing triflato ligands have in vitro promising antiproliferative activity against the murine melanoma B16.F10 cells.

Current drug research has been focusing on silver N-heterocyclic carbene (NHC) complex. Its metal-ligand bonds are stabilised by the strong-electron donor nature of NHC, ultimately increasing its antimicrobial properties. A series of imidazolium salts and their corresponding Ag(I)-NHC complexes with different NHC side chains in terms of alkyl chain length and mono/biscarbene functionalities have been successfully synthesised, characterised, and evaluated for their potential antimicrobial activities. It was shown that the imidazolium salts and Ag(I)-NHC complexes with long aliphatic alkyl N-1/N-3 side chains and bisimidazolium ligands possess promising bioactivities in general, with minimum inhibitory concentration (MIC) against microbes ranging from 0.12 to 7.81 µg/mL against selected six Gram-positive bacterial strains (Staphylococcus aureus and Enterococcus faecalis), two Gram-negative bacteria (Escherichia coli and Shigella flexneri) and two fungal strains (Candida albicans) for 2–7d & Ag-2–7d. It was found that the compounds with biscarbene structures (6d & Ag-6d) possess less toxic effects against immortalised human keratinocyte (HaCaT) cells. However, it must be noted that the toxic effect against HaCaT is higher among Ag(I)-NHC complexes (Ag-4d & Ag-6d) than their corresponding imidazolium salts (4d & 6d) in general. Hence, the variation of side chains, number of imidazolium centres and their respective cytotoxic effect provide insights into the future drug modification towards enhanced antimicrobial activities with minimal side effects.

The hard palate is a septum that not only prevents food from entering between the oral and nasal cavity, but also plays an important role during breathing or speech. The presence of cavities within it negatively affects the comfort of life of people with this type of impairment. Hence, in the literature one can find examples of the use of hard palate prostheses to restore the separation between the nasal and oral cavity.

During archaeological research conducted in 2017–18 in the church of St Francis of Assisi in Cracow, the remains of a man with a cleft palate, who died at the age of about 50, were found. His burial is dated to the eighteenth century. Within his mouth, the presence of a palatal prosthesis was noted. This is the first case in Poland of finding an individual with an obturator tailored to its needs.

The aim of the work is to present the structure and elemental composition of the found prosthesis and comparisons to the other obturators known from written sources.

Macroscopic analysis showed the presence of an elliptical-shaped metal diaphragm and a textile “tampon” entering nasal cavity. The metal part of the prosthesis was made of copper alloy, covered with a layer of silver and gold. The comparison of the analysed obturator with examples from the literature indicates its great similarity to those used in the sixteenth and eighteenth centuries.

Antibiotic resistance is a critical and expanding problem for public health, as well as a significant challenge for the pharmaceutical and medical industries. Pathogenic bacteria that are resistant to antibiotics are developing at a rate that is far faster than new drug development. Therefore, there is an urgent need for a novel class of antibiotics with a distinct mode of action with better effect. In this context, noble metal nanoparticles (NPs) (i.e. Ag, Au, Cu) and graphene oxide (GO) based nanocomposite materials have emerged as novel nanohybrid materials owing to their characteristics which combine to provide excellent antibacterial effects. These nanohybrids have been engineered and extensively investigated in recent years with a diverse range of applications including their antibacterial applications. This short review envisages the recent advances carried out in understanding the various antibacterial activities of noble metal NPs-GO nanohybrids with emphasis on the engineering of nanostructures and synergetic mechanisms of antibacterial actions. The synergetic antibacterial mechanism has been discussed, emphasizing the distinct role of GO and noble metal NPs towards combined antibacterial activities. Furthermore, the latest developments and antibacterial applications of such promising GO-noble metal NPs-based nanohybrids have been discussed followed by outlook and future prospects.

Iodine-containing coatings were prepared on pure Ti surfaces via electrochemical deposition to enhance their antibacterial properties. The factors influencing iodine content were analyzed using an orthogonal experiment. The electrochemically deposited samples were characterized using scanning electron microscopy with energy dispersive spectroscopy and X-ray photoelectron spectroscopy, and their antibacterial properties and cytotoxicity were evaluated. The results showed that changing the deposition time is an effective way to control the iodine content. The iodine content, coating thickness, and adhesion of the samples increased with deposition time. Iodine in the coatings mainly exists in three forms, which are I₂, I₃⁻, and pentavalent iodine. For samples with iodine-containing coatings, the antibacterial ratios against E. coli and S. aureus were greater than 90% and increased with increasing iodine content. Although the samples with iodine-containing coatings showed some inhibition of the proliferation of MC3T3-E1 cells, the cell viabilities were all higher than 80%, suggesting that iodine-containing coatings are biosafe.

Biosynthesis of metallic silver nanoparticles (AgNPs) has gained much interest and offers an attractive alternate to physical and chemical approaches. In recent year several safe, easy, cost-effective, reproducible, and environmentally friendly synthesis approaches for silver nanoparticles have been developed. In this research work, a simple, cheap, and unexplored method was applied on green synthesis of AgNPs using secondary metabolites extracted from Bixa orellana seeds. The seeds are rich of flavonoids and phenolic compounds which presumably responsible for the fast reduction and stabilization of silver ion into silver nanoparticles. The biosynthesis process is very likely to be able to reduce silver ions under simple physiological conditions. The surface plasmon resonance (SPR) that was appeared at 420 nm in UV–vis spectrum, had confirmed the formation of AgNPs. Moreover, the functional groups in secondary metabolite that act as reducing, capping and stabilizing agents for silver nanoparticles, are identified by Fourier transform infrared (FTIR) spectra. An X-ray diffraction analysis generated four peaks for Bixa orellana seed extract mediated AgNPs positioned at 2θ angles of 38.1°, 44.2°, 64.6°, and 77.5° corresponding to crystal planes (1 1 1), (2 0 0), (2 2 0), and (3 1 1). Field emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM) images confirmed the formation of nanosized silver particles. The z-average of the synthesized particles measured by dynamic light scattering (DLS) was found to be 92.9 nm. AgNPs synthesized exhibited remarkable antioxidant activity, antibacterial and antiproliferative activity against human breast (MCF-7) cell line. On the basis of our results, we conclude that biologically synthesized AgNPs exhibited favorable characteristics and have the potential to be used in biomedical fields.