Silver Cations Research Articles

Comparison of methods for the synthesis of silver nanoparticles stabilized in a solid polymethacrylate matrix

Silver nanoparticles were synthesized inside the small plates of transparent polymer medium by reduction of silver cations. The difference in morphology and sizes of nanoparticles synthesized by chemical, photochemical and thermal reduction was revealed, which depends both on the component ratio of the mixture and on the reduction time for the specific component ratio The polymethacrylate matrix itself acts as the stabilizing agent. A colorimetric sensor based on polymethacrylate matrix and silver nanoparticles was developed for the detection of hydrogen peroxide. The optical properties of the sensor were characterized by spectrophotometer using the surface plasmon resonance. A colorimetric sensor with nanoparticles undergoing to thermal reduction showed a quick result for the determination of hydrogen peroxide in the range 0.2–4.4 mM with a detection limit 0.1 mM.

How inert is single‐stranded DNA towards DNA‐stabilized silver nanoclusters? A case study.

A case study, detailing the effect of different DNA strands on a NIR‐emitting DNA‐stabilized silver nanocluster (DNA‐AgNC), is reported. The presence of single‐stranded DNA oligomers was found to adversely affect the chemical stability of (DNA)2[Ag16Cl2]8+ with distinct degrees of destruction depending on the DNA sequence. To increase the chemical stability of the DNA‐AgNC, we implemented two protection strategies. First, hybridization of the bare DNA strands with the corresponding complementary sequences dramatically reduced the destruction of (DNA)2[Ag16Cl2]8+, as demonstrated by the decreased drops in both the absorption and emission spectra. Secondly, passivation of the bare DNA oligomers with silver cations left (DNA)2[Ag16Cl2]8+ intact. Our investigation can thus provide an easy‐to‐implement approach to discover DNA sequences that are intrinsically less reactive towards preformed DNA‐AgNCs, and give an idea on how to protect DNA‐AgNCs from bare DNA strands.

Fluoro and Trifluoromethyl Benzoyl Hypoiodite Complexes with Substituted Pyridines.

Based on the prior observation of the trifluoroacetate hypoiodite, CF3C(O)OI, demonstrating the largest σ-hole of a neutral halogen bond donor, a series of mono- and bis-carbonyl hypoiodites utilising trifluoromethyl or fluorine substituents at various positions of a parent benzoyl skeleton have been synthesised. The carbonyl hypoiodite complexes were prepared via cation exchange of the silver(I) cations with iodine(I) from the respective silver(I) carboxylates and dicarboxylates as the synthetic precursors. A range of pyridinic Lewis bases of varying nucleophilicities were used to stabilise the carbonyl hypoiodites to further probe their properties. The silver(I) intermediates with these Lewis bases were also isolated for silver(I) pentafluorobenzoate, providing additional insight into the cation exchange reaction. All complexes were characterised both in solution (1H, 1H-15N HMBC, 19F) and in the solid state (SCXRD), permitting insights into the formation of the elusive pyridine-iodine(I) cation.

Poly[(μ-2,3-diethyl-7,8-di-methyl-quinoxaline-κ2N:N)(2,3-diethyl-7,8-di-methyl-quinoxaline-κN)-μ-nitrato-κ2O:O'-nitrato-κ2O,O'-disilver(I)].

The structure of the title compound, [C14H18N2)2Ag2](NO3)2, contains subtle differences in ligand, metal, and counter-anion coordination. One quinoxaline ligand uses one of its quinoxaline N atoms to bond to one silver cation. That silver cation is bound to a second quinoxaline which, in turn, is bound to a second silver atom; thereby using both of its quinoxaline N atoms. A nitrate group bonds with one of its O atoms to the first silver and uses the same oxygen to bond to a silver atom (related by symmetry to the second), thereby forming an extended network. The second nitrate group on the other silver bonds via two nitrate O atoms; one silver cation therefore has a coordination number of three whereas the second has a coordination number of four. One of the quinoxaline ligands has a disordered ethyl group.

Solvothermal growth of silver-doped vanadium pentoxide microurchins as a cathode material for all-solid-state asymmetric supercapacitors

This study aims to improve the electrochemical properties of vanadium pentoxide by inserting silver cations into the vanadium oxide lattice. The porous silver-doped V2O5 (Ag-V2O5) microurchins were grown via a facile one-step solvothermal process. The enhanced mesoporosity and interlayer d-spacing upon silver-doping, as confirmed by Brunauer–Emmett–Teller (BET) and X-ray diffraction analyses, played an important role in facilitating the intercalation/de-intercalation of electrolyte ions and thus enhancing the capacitive performance of V2O5. The Ag-V2O5 electrode delivered a superior capacitance of 535.6 F/g at 0.5 A/g and a higher rate capacity of 78.8% in non-aqueous lithium perchlorate electrolyte compared to sodium perchlorate electrolyte. Furthermore, the specific capacitance of V2O5 was remarkably increased by ∼56% upon 5.33 at% Ag-doping. An all-solid-state asymmetric supercapacitor (ASC) was fabricated using Ag-V2O5 as the cathode, activated carbon cloth as the anode, and LiClO4-loaded poly(acrylonitrile-co-1-vinylimidazole-co-itaconic acid) as a solid electrolyte. The ASC was stably operating in a wide potential window of 0–1.6 V and delivered a high energy of 53.8 Wh kg−1. Most importantly, the ASC exhibits a slow self-discharge rate with only 7.7% voltage loss after 17 h when charged at 1.6 V. Hence, these impressive electrochemical performances of Ag-V2O5 make it a promising cathode material for next-generation supercapacitors.

Combinatorial characterization of metastable luminous silver cations

Thermodynamically metastable glasses that can contain metastable species are important functional materials. X-ray absorption near-edge structure (XANES) spectroscopy is an effective technique for determining the valence states of cations, especially for the doping element in phosphors. Herein, we first confirm the valence change of silver cations from monovalent to trivalent in aluminophosphate glasses by X-ray irradiation using a combination of Ag L3-edge XANES, electron spin resonance, and simulated XANES spectra based on first-principles calculations. The absorption edge of the experimental and simulated XANES spectra demonstrate the spectral features of Ag(III), confirming that AgO exists as Ag(I)Ag(III)O2. A part of Ag(I) changes to Ag(III) by X-ray irradiation, and the generation of Ag(III) is saturated after high irradiation doses, in good agreement with conventional radiophotoluminescence (RPL) behaviour. The structural modelling based on a combination of quantum beam analysis suggests that the local coordination of Ag cations is similar to that of Ag(III), which is confirmed by density functional theory calculations. This demonstration of Ag(III) in glass overturns the conventional understanding of the RPL mechanism of silver cations, redefining the science of silver-related materials.

Metal-Complex Inks for Lower Cost and Improved Passivation for Silicon Photovoltaic Metallization

This contribution introduces the silicon PV community to screen-printable metal-complex inks that potentially will reduce Ag usage in Si PV metallization to one-quarter and costs to one-third that of traditional particle-based pastes while also improving passivation. Metal-complex inks are formulated using a Tollen’s reaction to produce inks with a high percentage of diamminesilver (I) cations (22 wt %) in a solution of acetate and formate anions. When printed and dried, labile ammonia ligands evaporate, leaving behind silver cations which, when reduced by formate anions and acetic acid, plate out silver and silver acetate. When annealed to just 300 °C a dense metallic silver film forms with excellent conductivity, and adhesion to silicon. When compared to traditional particle-based screen-printing pastes, the metal-complex inks are much denser, have higher conductivity, use less Ag, and are a fraction of the cost. Importantly, the inks anneal from 90 – 450 °C allowing for improved passivation schemes compared with fired SiNx. This contribution highlights first experiments on the improved passivation of metallized poly-Si/SiO2 passivated contacts using metal-complex Ag inks.

Metal Complexes Containing Homoleptic Diorganoselenium(II) Ligands: Synthesis, Characterization and Investigation of Optical Properties.

[(Z)-2'-{2-C6H5-(4H)-oxazol-5-one}CHC6H4]2Se (5, L1) and [(Z)-4'-{2-C6H5-(4H)-oxazol-5-one}CHC6H4]2Se (6, L2) were prepared, structurally characterized and used as ligands to obtain new metal complexes of types [MX(Ln)] [L1: M = Ag, X = OTf (7); M = Au, X = Cl (13); L2: M = Ag, X = OTf (8); M = Au, X = Cl (14)], [(MX)2(Ln)] [M = Ag, X = OTf, L1 (9); L2 (10)], [ZnCl2(Ln)] [L1 (15); L2 (16)] and [Ag(Ln)][PF6] [L1 (11); L2 (12)]. The silver complexes 7 and 8 were ionic species (1:1 electrolytes) in a MeCN solution, while in the solid state, the triflate fragments were bonded to the silver cations. Similarly, the 2:1 complexes 9 and 10 were found to behave as 1:2 electrolytes in a MeCN solution, but single-crystal X-ray diffraction demonstrated that compound 9 showed the formation of a dimer in the solid state: a tetranuclear [Ag(OTf)]4 built through bridging triflate ligands was coordinated by two bridging organoselenium ligands through the nitrogen from the oxazolone ring and the selenium atoms in a 1κN:2κSe fashion. Supramolecular architectures supported by intermolecular C-H∙∙∙π, C-H∙∙∙O, Cl∙∙∙H and F∙∙∙H interactions were observed in compounds 4, 5 and 9. The compounds exhibited similar photophysical properties, with a bathochromic shift in the UV-Vis spectra caused by the position of the oxazolone ring on the phenyl ring attached to the selenium atoms.

Antimicrobial and Virus Adsorption Properties of Y-Zeolite Exchanged with Silver and Zinc Cations.

The antimicrobial activity of silver and zinc exchanged cations in Y-zeolite (Ag/CBV-600, Zn/CBV-600) is evaluated against Staphylococcus aureus (gram (+)) and Escherichia coli (gram (-)) bacteria along with their adsorption capacity for viruses: brome mosaic virus (BMV), cowpea chlorotic mottle virus (CCMV), and the bacteriophage MS2. The physicochemical properties of synthesized nanomaterials are characterized by inductively coupled plasma optical emission spectroscopy (ICP-OES), UV-Vis spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM). According to the obtained results, the main species associated with the exchanged ions are Ag+ and Zn2+ cations with the concentration of around 1 atomic %. The incorporation of cations does not modify the Y-zeolite framework. The Ag/CBV-600 and Zn/CBV-600 materials show an inactivation of 90% for both gram (+) and gram (-) bacteria at 16 h at a relatively low concentration of nanomaterial (0.5 mg/mL). Moreover, the samples present good adsorption capacity for BMV, CCMV, and MS2 viruses showing adsorption higher than 40% after 2 h of interaction with the viruses. These prominent results allow the further usage of nanomaterials as an effective remedy to inhibit and reduce the spread of viruses such as SARS-CoV-2 or other gram (+) or gram (-) bacteria.

Designing Optical Anisotropy: Silver-Aminoalkylpyridine Nitrate Complexes with Tunable Structures.

To introduce a design strategy for improving optical properties, two silver-amino alkylpyridine nitrate complexes, AgC6H8N3O3 and Ag2C14H20N6O6, were successfully synthesized using a recrystallization method. By employing polarizable π-conjugated [NO3-] ions, two types of pyridine ligands, and silver cations with a high affinity for pyridine, we obtained a one-dimensional chain structure with 4-aminomethylpyridine (AgC6H8N3O3) and a zero-dimensional molecular compound by introducing a relatively flexible aliphatic chain with 4-(2-aminoethyl)pyridine (Ag2C14H20N6O6). The compounds crystallize in the triclinic crystal system with the centrosymmetric P-1 space group, exhibiting a change in orientation between the π-conjugated system and the silver ion. Despite similar optical band gaps (3.69 eV for AgC6H8N3O3 and 3.73 eV for Ag2C14H20N6O6), AgC6H8N3O3 shows higher absorption in the 350-600 nm range. Electronic structure calculations support the ultraviolet absorption findings, suggesting that charge transfer with π-conjugated systems influences birefringence. Ag2C14H20N6O6 exhibits experimental birefringence (0.261@546.1 nm) surpassing that of AgC6H8N3O3 (0.212@546.1 nm), placing it among the highest recorded values within metal-pyridine incorporating nitrate complexes. The nonconventional orientation of π-conjugated [NO3-] ions contributes to this phenomenon, enhancing the action of free π-conjugated orbitals. This design strategy for micromodulating the alignment of the π-conjugated system promises to be an effective approach for enhancing optical properties, such as birefringence.

Formation and Nanomechanical Properties of Silver-Mediated Guanine DNA Duplexes in Aqueous Solution.

Silver cations can mediate base pairing of guanine (G) DNA oligomers, yielding linear parallel G-Ag+-G duplexes with enhanced stabilities compared to those of canonical DNA duplexes. To enable their use in programmable DNA nanotechnologies, it is critical to understand solution-state formation and the nanomechanical stiffness of G-Ag+-G duplexes. Using temperature-controlled circular dichroism (CD) spectroscopy, we find that heating mixtures of G oligomers and silver salt above 50 °C fully destabilizes G-quadruplex structures and converts oligomers to G-Ag+-G duplexes. Electrospray ionization mass spectrometry supports that G-Ag+-G duplexes form at stoichiometries of 1 Ag+ per base pair, and CD spectroscopy suggests that as the Ag+/base stoichiometry increases further, G-Ag+-G duplexes undergo additional morphological changes. Using liquid-phase atomic force microscopy, we find that this excess Ag+ enables assembly of long fiberlike structures with ∼2.5 nm heights equivalent to a single DNA duplex but with lengths that far exceed a single duplex. Finally, using the conditions established to form single G-Ag+-G duplexes, we use a surface forces apparatus (SFA) to compare the solution-phase stiffness of single G-Ag+-G duplexes with dG-dC Watson-Crick-Franklin duplexes. SFA shows that G-Ag+-G duplexes are 1.3 times stiffer than dG-dC duplexes, confirming gas-phase ion mobility spectrometry measurements and computational predictions. These findings may guide the development of structural DNA nanotechnologies that rely on silver-mediated base pairing.

Разработка нового нанобиотехнологического метода и его применение для дифференциальной диагностики опухолей придаточного аппарата глаза

Aim: to develop a new nanobiotechnology method for the differential diagnosis of ocular adnexal tumors. Patients and Methods: 192 eyelid or conjunctival tumor samples from 192 patients were examined. Controls were healthy tissue samples from the same eye. To register and obtain significant differences in the generation of biogenic silver nanoparticles in situ, the key parameters of the reaction of the reduction of silver cations were selected and optimized. To generate de novo biogenic silver nanoparticles, tissue samples were placed in a sterile solution of a cation source in aseptic conditions. Nanoparticles were generated in situ using a sterile solution of Tollens' reagent (Ag(HN3)2NO3). Results: the optimal parameters of a new nanobiotechnology method were established to conduct the reduction reaction to generate biogenic silver nanoparticles. The required concentration of Tollens' reagent (source of cations) was 63 μg/ml. The wavelength used to observe the de novo generation of biogenic silver nanoparticles (λ) was 410 nm. Obtaining the most significant changes in the optical density of the reaction mixture with biogenic nanoparticles required 10 to 20 min, although the first changes were documented starting from the 5th minute of the reduction reaction. Benign and malignant tumors are characterized by different metabolic activities, i.e., benign eyelid and conjunctival tumors reduce cations more slowly than malignant tumors. The parameters of reducibility of benign ocular adnexal tumors did not significantly differ depending on tumor location and type. Among the malignant conjunctival tumors, melanoma is characterized by the highest reducibility p<0.05). Among the malignant eyelid tumors, no significant differences were found for different tumor types. Conclusions: this novel nanobiotechnology method provides a differential diagnosis of benign and malignant ocular adnexal tumors. The practical relevance of this method lies in differentiating benign and malignant tumors to schedule management strategies and surgical interventions. KEYWORDS: tumor, eyelids, conjunctiva, silver nanoparticles, biogenic synthesis, express diagnostics, ocular oncology. FOR CITATION: Saakyan S.V., Skladnev D.A., Alekseeva A.P., Beznos O.V., Sorokin V.V. Development of a new nanobiotechnology method for the differential diagnosis of ocular adnexal tumors. Russian Journal of Clinical Ophthalmology. 2024;24(1):25–29 (in Russ.). DOI: 10.32364/2311-7729-2024-24-1-5.

Reactivity of cationic silver clusters with O2: a probe of interplay between clusters' geometric and electronic structures.

We explored the size-dependent reactivity of Agn+ (n = 2-22) with O2 under mild conditions and found that only a few sizes of Agn+, with even values of n = 4, 6, 12, 16, 18, and 22, are reactive. Possible structures of Agn+ (n = 2-22) were determined using a genetic algorithm with incomplete local optimizations at the DFT level, and the calculated bonding strengths of O2 on these structures are consistent with experimental observations. Analyses revealed a close relationship between the reactivity of Agn+ with O2 and its HOMO-LUMO gap: cationic silver clusters with a small HOMO-LUMO gap are reactive, which can be rationalized by the covalent character of chemical bonds between Agn+ and O2 involving their frontier orbitals. The peculiar size-dependent HOMO-LUMO gaps and reactivity with O2 correlate with the subtle interplay between the electronic configurations and geometric structures of these silver cluster cations.

Antimicrobial and Cell-Friendly Properties of Cobalt and Nickel-Doped Tricalcium Phosphate Ceramics.

β-Tricalcium phosphate (β-TCP) is widely used as bone implant material. It has been observed that doping the β-TCP structure with certain cations can help in combating bacteria and pathogenic microorganisms. Previous literature investigations have focused on tricalcium phosphate structures with silver, copper, zinc, and iron cations. However, there are limited studies available on the biological properties of β-TCP containing nickel and cobalt ions. In this work, Ca10.5-xNix(PO4)7 and Ca10.5-xCox(PO4)7 solid solutions with the β-Ca3(PO4)2 structure were synthesized by a high-temperature solid-state reaction. Structural studies revealed the β-TCP structure becomes saturated at 9.5 mol/% for Co2+ or Ni2+ ions. Beyond this saturation point, Ni2+ and Co2+ ions form impurity phases after complete occupying of the octahedral M5 site. The incorporation of these ions into the β-TCP crystal structure delays the phase transition to the α-TCP phase and stabilizes the structure as the temperature increases. Biocompatibility tests conducted on adipose tissue-derived mesenchymal stem cells (aMSC) using the (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) (MTT) assay showed that all prepared samples did not exhibit cytotoxic effects. Furthermore, there was no inhibition of cell differentiation into the osteogenic lineage. Antibacterial properties were studied on the C. albicans fungus and on E. coli, E. faecalis, S. aureus, and P. aeruginosa bacteria strains. The Ni- and Co-doped β-TCP series exhibited varying degrees of bacterial growth inhibition depending on the doping ion concentration and the specific bacteria strain or fungus. The combination of antibacterial activity and cell-friendly properties makes these phosphates promising candidates for anti-infection bone substitute materials.

Experimental investigation and thermodynamic assessment of phase equilibria in the GaTe–AgGa5Te8–Te system below 600 K

Equilibrium T–x space of the Ag–Ga–Te system in the GaTe–AgGa5Te8–Te part was divided below 600 K into three-phase regions Ga2Te5–AgGa5Te8–Te, Ga2Te3–AgGa5Te8–Ga2Te5, Ga7Te10–AgGa5Te8–Ga2Te3, Ga3Te4–AgGa5Te8–Ga7Te10, and GaTe–AgGa5Te8–Ga3Te4 by the electromotive force (EMF) method. To accomplish accurate experimental data, the following electrochemical cells (ECs) were assembled: (−)IE|NE|SSЕ|R{Ag+}|PЕ|IE(+), where IE is the inert electrode (graphite powder), NE is the negative electrode (silver powder), SSE is the solid-state electrolyte (glassy Ag3GeS3Br), PE is the positive electrode, R{Ag+} is the region of PE that contact with SSE. At the stage of cell preparation, PE is a nonequilibrium phase mixture of the well-mixed powdered compounds Ag2Te, GaTe, Ga2Te3, and tellurium, taken in ratios corresponding to two or three different points in each of the mentioned regions. The equilibrium set of phases was formed in the R{Ag+} region at 600 K for 48 h with the participation of the Ag+ ions. Silver cations, displaced for thermodynamic reasons from the NE to the PE of the ECs, acted as catalyst, i.e., small nucleation centers of equilibrium phases. The spatial position of the established three-phase regions relative to the silver point was used to assign the overall potential-determining reactions of synthesis of the ternary AgGa5Te8 and binary Ga2Te5, Ga7Te10, Ga3Te4 compounds. For the first time, the values of the standard thermodynamic functions (Gibbs energies, enthalpies, and entropies) of these compounds were determined based on the temperature dependences of the EMF of the ECs.

Detection of silver cation based on phenothiazine derivative probe

In this work, a novel probe 1 has been prepared via two-step reaction from o-phenylenediamine. The recognition properties of probe 1 for different metal ions in DMF solution were investigated by UV absorption spectroscopy and fluorescence spectroscopy, respectively. The color of the solution changed from light yellow to light purple, then became brown after half an hour when Ag[Formula: see text]was added to the DMF solution of probe 1. Ag[Formula: see text] can also be easily and quickly identified by using the test strips prepared. 1 has also high selectivity and sensitivity for Ag[Formula: see text] even in the presence of other metal ions. After adding Ag[Formula: see text], the fluorescence quenching appeared and the lowest detection limit of Ag[Formula: see text] is 2.90 [Formula: see text]M. Furthermore, the 1H NMR test and density functional theory calculation have verified the sensing behavior mechanism. The detection of silver cation provided here is rapid and effective, and it is a beneficial exploration for the development of high efficiency ion sensors.

Experimental and Theoretical Structure Elucidation of the [2 : 1] Complex Ion of Carbo[n]helicene with n=6, 7 and 8 and Ag.

The front cover artwork illustrates the competition of [6]-, [7]- and [8]helicene for attaining a silver(I) cation. This struggle takes place in the electrospray process during solvent evaporation, leading to the well-known tweezer-like surrounding of Ag+ by the helicene in the [1:1] complex. In this competition, the larger helicenes outperform the smaller ones. The main topic of our investigation, however, is the resulting [2:1] complex in which a second helicene attaches via π-π stacking to the [1:1] tweezer complex. Read the full text of the Research Article at 10.1002/cphc.202300496.

Linear bis-Coordinate Silver(I) and Iodine(I) Complexes with R3R2R1NTertiary Amines.

Homoleptic [L-I-L]⁺ iodine(I) complexes (where L is a R3R2R1N tertiary amine) were synthesized via the [L-Ag-L]⁺ → [L-I-L]⁺ cation exchange reaction. In solution, the amines form [R3R2R1N-Ag-NR1R2R3]⁺ silver(I) complexes, which crystallize out from solution as the meso-[L-Ag-L]+complexes, as characterized by X-ray crystallography. The subsequent [L-I-L]⁺ iodine(I) analogues were extremely reactive and could not be isolated in the solid state. Density Functional Theory (DFT) calculations were performed to study the Ag⁺-N and I⁺-N interaction energies in silver(I) and iodine(I) complexes, with the former ranging from -80 to -100 kJmol-1 and latter from -260 to -279 kJmol-1. The X-ray crystal structures revealed Ag+···Cπ and Ag+···H-C short contacts between the silver(I) cation and flexible N-alkyl/N-aryl groups, which are the first of their kind in such precursor complexes.

Surface-Assisted Laser Desorption/Ionization Mass Spectrometry Analysis of Latent Fingermarks Using Greenly Synthesized Silver Nanoparticles

Advances in nanotechnology have contributed to many innovative approaches in the forensic sciences, including the development of new techniques and protocols for latent fingermark detection. Among other nanomaterials, metal-based nanoparticles have been explored as suitable developers for fingermarks present on surfaces that challenge traditionally established methods. The present study explored, for the first time in the forensic science literature, the application of greenly synthesized silver nanoparticles (AgNPs) for latent fingermark surface-assisted laser desorption/ionization mass spectrometry (SALDI MS) analysis. A leaf extract of a native plant from the Cerrado biome was used for green synthesis of the AgNPs, and their hydrodynamic diameter, polydispersity index (PdI), and Zeta potential values were evaluated. Latent fingermarks were produced by three distinct donors and treated with α-CHCA matrix or AgNP suspension and were further investigated using commercial matrix assisted laser desorption/ionization (MALDI)-TOF MS equipment in the m/z range of 100–1000. Characterization results of the AgNPs indicated an average hydrodynamic diameter of 25.94 ± 0.30 nm, a PdI of 0.659 ± 0.085, and a Zeta potential of −33.4 ± 2.6 mV. The silver ions detected showed a relative intensity at least 20× higher for greenly synthesized AgNPs than for AgNO3 suspension, which may be advantageous for the detection of molecular species, especially olefins, present in forensic traces. The AgNP-based SALDI MS approach for the analysis of latent fingermarks showed intense ions at m/z 106.9, 215.8, and 322.7, referring to silver cation species that have been reported as important internal calibrants. The detection of components from endogenous and exogenous sources in latent fingermarks was achieved using the present approach. Greenly synthesized AgNPs may offer a new cost-effective, eco-friendly, and easily scaled up method for application in the chemical analysis of fingermarks.

Silver-substituted hydroxyapatite: Mechanochemical synthesis and thermal stability

Silver-substituted hydroxyapatites have been prepared by the mechanochemical method in a planetary ball mill. In order to prepare a series of samples of the Ca10−xAgx (PO4)6(OH)2−x composition, the concentration of silver was varied in the range x = 0–2. The resultant samples were characterized by means of X-ray diffraction, FTIR spectroscopy, and simultaneous thermal analysis. It was shown that the single-phase substituted hydroxyapatites were achieved with silver concentrations of up to х = 1.5. An increase in the concentration of silver results in an increase in the volume and the unit-cell parameters of crystals. At a concentration x of 2.0, the sample contains an impurity phase of silver phosphate. The thermal stability of the as-synthesized silver-substituted samples was shown to directly depend on the degree of substitution of calcium cations by silver cations. The decomposition temperature decreases as the degree of substitution increases. Upon heating of the substituted samples, silver is gradually released from hydroxyapatite with the formation of a metallic nanosized silver phase, followed by the structural transformation of the hydroxyapatite lattice into silver-substituted tricalcium phosphate at a higher temperature. In this case, the introduction of silver cations results in a decrease in the values of the lattice parameters of tricalcium phosphate, showing a non-linear dependence on the silver concentration.