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X-ray diffraction patterns of (a) elemental silver isolated from thin gelatinous layer with black phase and (b) elemental silver isolated from thin layer of gelatin containing red phase.
Source publication
Elemental silver incorporated into thin glass-like gelatin films by the reprecipitation of elemental silver initially contained in them is studied by the methods of X-ray diffraction analysis and scanning electron microscopy. For the reprecipitation, silver undergoes a redox process by the following scheme: Ag → AgHal → Ag. It is shown that silver...
Context in source publication
Context 1
... 144.4, 123.1, and 117.9 pm in the X-ray diffraction pattern of the initial black form (Fig. 1). Typically, the position of the reflections does not depend on the nature of alkaline metal halide present in an oxidizing solution, the nature of an organic or inorganic compounds present in a reducing solution, or on their concentrations in the appropriate solutions. ...
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Citations
... The reducing agent is an organic or inorganic substance with strongly pronounced electron-donor properties. One of the most suitable for this purpose is tin dichloride SnCl2, which was used to obtain gelatin-immobilized Ag-NP in [198][199][200][201]. The reduction according to the Ag(I)→Ag scheme occurred in a strongly alkaline (pH~12) medium in the presence of reagents capable of forming fairly strong and water-soluble complexes with Ag(I) (thiocyanate anion SCN − , thiosulfate anion S2O3 2-, ammonia NH3, ethylenediamine, monoethanolamine, etc.). ...
The data on the specifics of synthesis of elemental silver nanoparticles (Ag-NP) having various geometric shapes (pseudo spherical, prismatic, cubic, trigonal-pyramidal, etc.), obtained by using various biological methods, and their use in biology and medicine have been systematized and generalized. The review covers mainly publications published in the current 21st century. Bibliography: 262 references.
... In most cases, however, such an image consists of microparticles, but in some cases, as a result of the processes of so-called "re-precipitation" of elemental silver, as it was shown in a recently published paper [57], the formation of Ag-NP occurs. However, the idea that due to specific conditions of chemical processes in gelatin films, as well as the specific structure of this high-molecular compound itself, nanoparticles of the most diverse chemical compounds would appear in it, was expressed in a number of works, in particular, in review articles [58][59][60][61][62], even before the publication of the paper [57]. With using this approach, the synthesis of pseudo-spherical Ag-NP in the gelatin matrix was realized in [63][64][65][66]. ...
... The size of Ag-NP formed in this case was in a rather wide range -from 10 to 40 nm; an example of the image of such Ag-NP contained in the gelatin-immobilized matrix was shown in Fig. (2a). It should be noted in connection with this that, when these nanoparticles are isolated from the gelatin matrix (for example, by influence on it of proteolytic enzymes as it was described in [67]) naturally, their agglomeration takes place; nevertheless, a considerable part of these particles remains a nano-sized ( Fig. 2b) [57]. Details of the process of obtaining Ag-NP using such a specific method were presented in [63][64][65][66]. ...
... Authors of [79] using soft chemical reduction method in aqueous solutions of poly(methacrylic acid) produced Ag nanowires at room temperature with 30-40 nm a b Fig. (2). SEM of pseudo-spherical Ag-NP obtained as a result process of "re-precipitating" of silver contained in gelatin matrix (a) and Ag-NP isolated from this matrix (b) [57]. ...
Background
The data on the specific synthesis of elemental silver nanoparticles (Ag-NP) having the forms of various geometric bodies (pseudo spherical, prismatic, cubic, trigonal-pyramidal, etc.), obtained by various methods, have been systematized and generalized.
Objective
It is noted that the forms and sizes of Ag-NP are greatly dependant on the conditions in which they are formed.
Method
Comparison of the data of the characteristics of silver nanoparticles obtained by chemical, physicochemical and biological methods has been made.
Results
It has been shown that form and size of produced Ag-NP depend strongly on the such factors as temperature, the concentration of silver(I) containing precursor, pH of the solution, the molar ratio between capping agent and silver(I) containing precursor, reducing agents etc., and, also, on the method used for Ag-NP synthesis (chemical, physicochemical or biological).
Conclusion
It has also been noted that biological methods of synthesis of Ag-NP are generally more preferable in comparison with the chemical and physicochemical methods. The review covers mainly publications published in the last 20 years.
... Gelatin-immobilized elemental silver has been known for a long time because it is nothing more than the "building material" of the black-white image obtained as a result of the halogen silver photographic process (Mees and James 1973, James 1977. In most cases, however, such an image consists of microparticles, but in some cases, as a result of the processes of so-called "re-precipitation" of elemental silver, as it was shown in a recently published paper (Mikhailov 2017), the formation of Ag-NPs occurs. However, the idea that due to specific conditions of chemical processes in gelatin films, as well as the specific structure of this high-molecular compound itself, NPs of the most diverse chemical compounds would appear in it was expressed in a number of works, in particular, in review articles (Mikhailov 2010, 2013, 2014a,b, Mikhailov et al. 2015, even before the publication of the paper (Mikhailov 2017). ...
... In most cases, however, such an image consists of microparticles, but in some cases, as a result of the processes of so-called "re-precipitation" of elemental silver, as it was shown in a recently published paper (Mikhailov 2017), the formation of Ag-NPs occurs. However, the idea that due to specific conditions of chemical processes in gelatin films, as well as the specific structure of this high-molecular compound itself, NPs of the most diverse chemical compounds would appear in it was expressed in a number of works, in particular, in review articles (Mikhailov 2010, 2013, 2014a,b, Mikhailov et al. 2015, even before the publication of the paper (Mikhailov 2017). Using this approach, the synthesis of pseudospherical Ag-NPs in the gelatin matrix was realized in Mikhailov et al. (2005Mikhailov et al. ( , 2008Mikhailov et al. ( , 2013, Mikhailov and Naumkina (2010). ...
... The size of the Ag-NPs formed in this case was in a rather wide range -from 10 to 40 nm; an example image of such Ag-NPs contained in the gelatin-immobilized matrix is shown in Figure 3A. It should be noted in connection with this that when these NPs are isolated from the gelatin matrix [for example, by influence on it of proteolytic enzymes as it was described in Mikhailov (1991)] naturally, their aggregation takes place; nevertheless, a considerable part of these particles remains a nanosize ( Figure 3B) (Mikhailov 2017). Details of the process of obtaining Ag-NPs using such a specific method were presented in Mikhailov et al. (2005Mikhailov et al. ( , 2008Mikhailov et al. ( , 2013, Mikhailov and Naumkina (2010). ...
The data on the specific synthesis of elemental silver nanoparticles having the forms of various geometric bodies (pseudo spherical, prismatic, cubic, trigonal-pyramidal, etc.), obtained by various chemical, physicochemical, and biological methods, have been systematized and generalized. This review covers mainly publications published in the current 21st century.
The data have been systematized and generalized on the specific synthesis of elemental silver nano-sized crystals (Ag-NC) having the forms of various geometric bodies (pseudo spherical, prismatic, cubic, trigonal-pyramidal, etc.), obtained by various chemical, physicochemical and biological methods. It has been noted, that the form of the synthesized Ag-NC can be controlled by changing the thermodynamic and kinetic parameters at each key stage of the synthesis (nucleation, seeding, and growth). Moreover, the size range of spherical and cubic silver nanocrystals can be influenced by either physical, chemical or biological methods during the synthesis, but such forms as nanorods, nanowires and nanobars can only be synthesized by chemical or physical methods at the present time. The review covers articles comprehensively mainly published in the last 20 years.
