A one-step simple synthesis of silver colloid nanoparticles with controllable sizes is presented. In this synthesis, reduction of [Ag(NH(3))(2)](+) complex cation by four saccharides was performed. Four saccharides were used: two monosaccharides (glucose and galactose) and two disaccharides (maltose and lactose). The syntheses performed at various ammonia concentrations (0.005-0.20 mol L(-1)) and pH conditions (11.5-13.0) produced a wide range of particle sizes (25-450 nm) with narrow size distributions, especially at the lowest ammonia concentrations. The average size, size distribution, morphology, and structure of particles were determined by dynamic light scattering (DLS), transmission electron microscopy (TEM), and UV/Visible absorption spectrophotometry. The influence of the saccharide structure (monosacharides versus disaccharides) on the size of silver particles is briefly discussed. The reduction of [Ag(NH(3))(2)](+) by maltose produced silver particles with a narrow size distribution with an average size of 25 nm, which showed high antimicrobial and bactericidal activity against Gram-positive and Gram-negative bacteria, including highly multiresistant strains such as methicillin-resistant Staphylococcus aureus. Antibacterial activity of silver nanoparticles was found to be dependent on the size of silver particles. A very low concentration of silver (as low as 1.69 mug/mL Ag) gave antibacterial performance.

In this work, a simple one-step method of silver nanoparticle (NPs) preparation with controlled size is introduced. Silver NPs were prepared by reduction of [Ag(NH 3 ) 2 ] + complex cation by D-maltose in the presence of low concentrations (1 × 10 −10 mol/L to 1 × 10 −7 mol/L) of high-molecular-weight poly(acrylic acid) (PAA). This modification of the reduction reaction results in managing of the prepared silver nanoparticles' size in the range from 28 nm (the reaction system without PAA) to 77 nm (system with the highest used PAA concentration). The presence of poly(acrylic acid) influences both nucleation process and also the subsequent stage of nanoparticle growth. The rate of nuclei formation by homogeneous nucleation is affected by PAA due to the formation of the strong complex with silver ions which results in a prolongation of the initiation phase of the reduction process proportionally to PAA concentration. The formation of the adsorption layer of PAA on the surface of the emerging silver nuclei prevents the direct contact between silver ions and nuclei, which is necessary for continuation of the nuclei growth via heterogeneous catalytical mechanism. Because of this restriction, the silver nuclei grow up to their final size by the aggregation mechanism. The as-prepared silver NPs were tested as efficient catalysts for redox reactions. For this purpose, a model reaction, the reduction of organic dye by sodium borohydride was used. The mechanism of this reaction is discussed using the Langmuir−Hinshelwood model of heterogeneous catalysis.

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