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Objective@#o explore the antibacterial effect of combined use of photon-induced photoacoustic streaming (PIPS) and silver nanoparticles (AgNPs) on Enterococcus faecalis biofilm in root canals.@*Methods@#A total of 36 isolated teeth with single root canal were collected to establish an experimental root canal model of Enterococcus faecalis infection. Samples were randomly divided into six groups and 0.9% NaCl, 2% NaClO, 0.1% AgNPs solutions were used with conventional needle irrigation (CNI) or PIPS for root canals. Colony count method was used to measure the number of Enterococcus faecalis biofilm in root canals before and after treatment, and the percentage of colony count reduction was calculated.@*Results@#The inhibitory effect of Enterococcus faecalis biofilm in all experimental groups was stronger than that in the control group (P<0.05). The decrease amplitude of 0.9% NaCl, 2% NaClO, 0.1% AgNPs assisted with PIPS was greater than that of 0.9% NaCl, 2% NaClO, 0.1% AgNPs assisted with CNI (P<0.05). The decrease in the 0.1% AgNPs assisted with PIPS group was significantly greater than that in the 2% NaClO assisted with PIPS group (P<0.05).@*Conclusion@#PIPS-assisted AgNPs solution washing can significantly improve the effect of clearing Enterococcus faecalis biofilm in root canals.
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Objective: This study attempted to investigate the effect of enamel deproteinization using citric acid, PEG 400 and NaOCL on the shear bond strength of orthodontic brackets to enamel using nano-silver modified resin for the prevention of white spot lesions. Material and Methods: 68 premolars were used in the study; nano-silver modified adhesive resin was used to bond orthodontic brackets to the enamel. Specimens were divided into 4 groups according to the applied surface treatment before bonding. Group I (control): acid etching with 37% phosphoric acid. Group II: deproteinization using 5.25% sodium hypochlorite (NaOCl) before acid etching. Group III:deproteinization using 10% citric acid before acid etching. Group IV:deproteinization using 5% polyethylene glycol (PEG 400) before acid etching. The specimens were then thermo- cycled for 6000 cycles. They were examined for surface roughness, shear bond strength and using electron microscope. Results: In both surface roughness and shear bond strength tests, Group III (citric acid) showed the highest values, followed by Group II (sodium hypochlorite); (p < 0.001). The least values were shown for Groups I (control) and IV (PEG 400), with no statistically significant difference between them (p = 0.948). SEM revealed etching pattern type 1 and 2 in the citric acid group while PEG 400 showed shallower micro- porosities. Conclusions: Deproteinization of enamel using either NaOCl or citric acid increased the bond strength of nano-sliver modified resin to enamel, with citric acid showing greater increase in bond strength. Deproteinization using PEG 400 did not increase the bond strength. (AU)
Objetivo: Este estudo buscou investigar o efeito da desproteinização do esmalte utilizando ácido cítrico, PEG 400 e NaOCl na resistência ao cisalhamento de braquetes ortodônticos ao esmalte usando resina modificada com nanoprata para a prevenção de lesões de manchas brancas. Material e Métodos: 68 pré-molares foram usados no estudo; resina adesiva modificada com nanoprata foi usada para colar os braquetes ortodônticos ao esmalte. Os corpos-de-prova foram divididos em 4 grupos de acordo com o tratamento de superfície aplicado antes da colagem. Grupo I (controle): condicionamento ácido com ácido fosfórico a 37%. Grupo II: desproteinização com hipoclorito de sódio a 5,25% (NaOCl) antes do condicionamento ácido. Grupo III: desproteinização com ácido cítrico a 10% antes do condicionamento ácido. Grupo IV: desproteinização com polietilenoglicol 5% (PEG 400) antes do condicionamento ácido. As amostras foram então termocicladas por 6.000 ciclos. Eles foram examinados quanto à rugosidade da superfície, resistência ao cisalhamento e usando microscópio eletrônico. Resultados: Nos testes de rugosidade superficial e resistência ao cisalhamento, o Grupo III (ácido cítrico) apresentou os maiores valores, seguido do Grupo II (hipoclorito de sódio); (p <0,001). Os menores valores foram apresentados para os Grupos I (controle) e IV (PEG 400), sem diferença estatisticamente significativa entre eles (p = 0,948). A microscopia eletrônica revelou padrão de ataque tipo 1 e 2 no grupo de ácido cítrico, enquanto PEG 400 mostrou microporosidades mais rasas. Conclusões: A desproteinização do esmalte com NaOCl ou ácido cítrico aumentou a força de união da resina modificada com nanoprata ao esmalte, com o ácido cítrico apresentando maior aumento na força de união. A desproteinização usando PEG 400 não aumentou a resistência de união. (AU)
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Sodium Hypochlorite , Citric Acid , Dental Cements , Dental EnamelABSTRACT
Background: The incidence of diabetes and its complications is rising as a result of the lifestyle changes. The foot is most frequent site for complication in patients with diabetes. Dressings have a vital part to play in the management of wounds. The ideal antiseptic is one that is lethal to all forms of bacteria, has no deleterious effect on healing tissues, delineates the operative areas, easily applied and has wide spectrum of activity and absence of acquired bacterial resistance. Nanotechnology makes it possible to expand the surface area of silver particles markedly to nanoscale. They expand the surface area of silver particles increasing their contact with bacteria.Methods: In the proposed study, over a period of 18 months, 60 cases (30-30 in 2 groups) of diabetic foot ulcers were studied with respect to response (healing) to nano silver dressing and betadine dressing after dividing them randomly. Assessment was based on various parameters like size reduction, healthy granulation tissue, etc.Results: It was seen that percentage reduction in size, was more in nano silver group as compared to betadine group. Wounds were managed successfully, early in nano silver group and wound healing was better in nano silver group as compared to betadine group. Also, nano silver was better antimicrobial.Conclusions: The prospective study showed nano silver gel is safe and effective in wound management and gives better efficacy and faster response as compared to traditional betadine dressing.
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Objective: To study the effects of room curing polymethyl methacrylate (PMMA) with nano-silver on the liver tissue and DNA damage of hepatic cells in the mice, and to evaluate the hepatotoxicity of the nanocomposites. Methods: A total of 40 male Kunming mice aged 6-8 weeks were divided into room curing PMMA with nano-silver groups (PMMA-NM groups, 72 h extract liquid, 1/2 72 h extract liquid, 1/4 72 h extract liquid), room curing PMMA groups (PMMA groups, 72 h extract liquid, 1/2 72 h extract liquid, 1/4 72 h extract liquid), negative control group, and positive control group (n=5). All mice were treated by gavage with test compounds at the beginning of experiment and 24 h and 45 h after experiment except the positive control agent, the mice in positive control group were treated with ethylmethylsulfone at 24 and 45 h after experiment, and the mice in negative control group were administrated with the same volume of normal saline by gavage. The eyeball blood of mice was collected for biochemistry analysis of liver 3 h after the final administration. The liver tissue was completely removed immediately after the mice were sacrificed and the organ coefficient was calculated. The percentage of tail DNA (%tail DNA), tail length (TL) and Olive tail moment (OTM) were detected by the in vivo comet assay, and the images were analyzed with analysis software of comet assay. Results: Compared with negative control group, the liver coefficient, the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in liver tissue of the mice in various experimental groups had no significant differences (P>0. 05); the % tail DNA, TL and OTM in PMMA-NM groups and PMMA groups had no significant differeces (P>0. 05). The % tail DNA, TL and OTM of the mice in positive control group were higher than those in negative control group (t= -40. 911, P0. 05). There were no significant differences of the % tail DNA, TL and OTM between PMMA-NM groups at different concentrations of extrat liquid (P>0. 05). Conclusion: Room curing PMMA with nano-silver doesn't have adverse effects on the liver and its function in the mice, and the results of comet assay indicates that the material has no genotoxicity, showing that the composite has good biocompatibility.
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Objective Paclitaxel and nanosilver were co-encapsulated into folic acid-albumin nanoparticles to increase the toxicity and uptake of the drug and improve the targeting ability of tumor that highly expressed folic acid (Fa) receptor. Methods The mean Fa binding number of bovine serum albumin (BSA) was determined by ultraviolet absorption method. The nanoparticles were prepared through self-assemble method and then its shape, partical size, Zeta potential, and encapsulation efficiency were characterized with the dynamic light scattering (DLS) and transmission electron microscope (TEM). In addition, the cellular uptake of nanoparticles and the in vitro anti-tumor effect of drug-loaded nanoparticles were investigated on the KB cells model of oral epithelial carcinoma. Results Ultraviolet absorption results showed that the average Fa binding number of Fa-BSA was 11. The nanoparticles were discrete and uniform spheres with the average size of (98.20 ± 3.58) nm and Zeta potential of (-39.90 ± 1.98) mV. Cellular uptake experiments showed that folate-modified albumin nanoparticles were more easily taken up by KB cells. Cytotoxicity and apoptosis assay indicated that the modification of folic acid and co-loaded nanosilver could increase the inhibition of tumor cell proliferation and promote KB cells apoptosis. Conclusion The prepared nanoparticles have small particle size and high encapsulation efficiency, which can enhance the ability of the nanoparticles to be uptaken and the toxicity of the drug-loaded nanoparticles against tumor cells.
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Objective To study the effects of nano silver (Ag) and titanium dioxide (TiO2) on the content of nucleic acid in staphylococcus aureus in order to explore their antibacterial mechanisms.Methods After preparation of beef extract peptone liquid cultures,the effects of minimal inhibitory concentrations (MICs) of nano Ag and TiO2 on staphylococcus aureus strains were determined.With the 1/2 MICs nano Ag and TiO2,the contents of DNA and RNA macromolecules from staphylococcus aureus cultures were measured to determine the damage degree of staphylococcus aureus cell membranes by ultraviolet spectrophotometer,and then the fluorescence intensities of the staphylococcus aureus cells were observed under fluorescence microscope and the fluorescence values were tested by fluorescence spectrophotometer to determine the contents of nucleic acid DNA and RNA.Results The MICs of nano Ag and TiO2 were 1.6 mg/mL and 5.781 μg/mL.After treatment with the 1/2 MICs nano Ag and TiO2,nano Ag group and TiO2 group were compared with the control group (culture fluid without adding antibacterial agent),respectively,and there were no significant differences in the contents of DNA and RNA macromolecules from staphylococcus aureus cultures between n anoAg group and control group as well as between TiO2 group and control group were (P＞0.05),and there were significant decreases in fluorescence intensities and the contents of nucleic acid DNA and RNA (P＜0.01).Conclusions Nano Ag and TiO2 had obvious antibacterial effects on staphylococcus aureus and the antibacterial properties of nano Ag was stronger than that of TiO2.The antibacterial mechanisms of nano Ag and TiO2 against staphylococcus aureus may be associated with the inhibition of the synthesis of nucleic acid DNA and RNA,inhibiting protein synthesis and then bacterial growth.
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Objective To evaluate the advantage of homemade negative pressure device combined with nano-silver dressing for promoting the healing of infected incision in rats,and explore its clinical curative effect.Methods In-fected incision model rats were randomly divided into conventional treatment group,and simple pressure suction group,pressure suction combined with silver ion dressing group.The healing time and healing area of rats in each group after treatment were evaluated,immunohistochemical and fluorescent quantitative analysis of inflammatory factors in incisional wound tissue were performed.Three methods were applied to patients with surgical site infec-tion(SSI),granulation coverage time,granulation recovery time,and incision healing time of three groups of pa-tients were compared.Results Immunohistochemistry and its IOD value,the relative mRNA expression levels of TNF-α,IL-2,and IL-8 in rat wound tissue treated with pressure suction combined with silver ion dressing were all inferior to conventional treatment group and simple negative pressure suction group,difference was statistically sig-nificant (P < 0.05);in clinical application,wound healing time,postoperative C-reactive protein level,and pain as-sessment scores in patients treated with pressure suction combined with silver ion dressing were all superior to con-ventional treatment group and simple negative pressure suction group,difference were all statistically significant (all P < 0.05).Conclusion Compared with conventional treatment method,pressure suction with silver ions dressing treatment can more effectively control SSI,reduce local inflammation of incision,and promote incision healing.
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Objective:To evaluate the bactericidal effects of nano-silver against Enterococcus faecalis(E.faecalis) growing in multi-species biofilm.Methods:85 biofilms were established using MBECTM P&G Assay with E.faecalis together with Fusobacterium nucleatum and P.melaninogenica.Thereafter,10 specimens were used as the controls,75 were randomly divided into 3 groups(n=25),and treated with 0.1% nano-silver (12-15 nm) solution,0.1% nano-silver (100 nm) solution and 2% hypochlorite solution,respectively.Each sample was then separated into 2 different tubes.PMA was added to one of the tubes,and the other was left untreated.Then,DNA extraction and qPCR were performed.The cycle threshold(Ct) values between samples were compared by paired t test.Results:The Ct values of the samples treated with PMA were higher than that without PMA(P=0.000) in the group of 0.1% nano-silver solution(12-15 nm)was higher than that in the group of 0.1% nano-silver solution(100 nm)and 2% sodium hypochlorite solution.(P<0.05);the value in the group of 0.1% nano-silver solution(100 nm)was larger than that in 2% sodium hypochlorite solution(P<0.05).Conclusion:0.1% nano silver solution might have a strong bactericidal effect against against E.faecalis growing in multi-species biofilm.The bactericidal effect may be enhanced with the small size of silver particles.
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Objective To evaluate the advantage of homemade negative pressure device combined with nano-silver dressing for promoting the healing of infected incision in rats,and explore its clinical curative effect.Methods In-fected incision model rats were randomly divided into conventional treatment group,and simple pressure suction group,pressure suction combined with silver ion dressing group.The healing time and healing area of rats in each group after treatment were evaluated,immunohistochemical and fluorescent quantitative analysis of inflammatory factors in incisional wound tissue were performed.Three methods were applied to patients with surgical site infec-tion(SSI),granulation coverage time,granulation recovery time,and incision healing time of three groups of pa-tients were compared.Results Immunohistochemistry and its IOD value,the relative mRNA expression levels of TNF-α,IL-2,and IL-8 in rat wound tissue treated with pressure suction combined with silver ion dressing were all inferior to conventional treatment group and simple negative pressure suction group,difference was statistically sig-nificant (P < 0.05);in clinical application,wound healing time,postoperative C-reactive protein level,and pain as-sessment scores in patients treated with pressure suction combined with silver ion dressing were all superior to con-ventional treatment group and simple negative pressure suction group,difference were all statistically significant (all P < 0.05).Conclusion Compared with conventional treatment method,pressure suction with silver ions dressing treatment can more effectively control SSI,reduce local inflammation of incision,and promote incision healing.
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Silver nanoparticles (AgNPs) have potential antimicrobial activity against bacteria and fungi. The synthesis of AgNPs have been reported using several chemical and physical methods which are not friendly environment. Therefore, our technique has focused on the synthesis of AgNPs by natural compounds. The aim of this study has been to synthesis AgNPs by safe nontoxic method using Egyptian honey (EH) as reducing and capping agents and to investigate its ability to reduce the mycelial growth and the production of aflatoxins (AFs) and ochratoxin A (OTA) by Aspergillus flavus and Aspergillus ochraceus, respectively. AgNPs have been characterized by UV-Visible Spectrophotometer, Dynamic Light Scattering (DLS), Fourier Transform Infrared Spectroscopy (FTIR), and Transmission Electron Microscope (TEM).The obtained results indicated that the synthesis of honey AgNPs depends on the concentration of bulk metal (AgNO3) used in the synthesis process. The TEM image has revealed the formation of spherical well dispersed AgNPs, while the main size of AgNPs detected by DSL is 9.9 nm. Our results have indicated that 3 mg -100 ml media of honey derived AgNPs have reduced the aflatoxin (AF) G1, G2, B1 andB2 production by A. parasiticus to 77.55, , 62.91, 58.76 and 66.56%, respectively and ochratoxin A (OTA) by A. ochraceus to 79.85 % with significantly inhibitory effect on mycelial growth. The percentage of reduction depends on the AgNPs concentration.
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Objective To explore the antibacterial activity and cytocompatibility of chitosan-nano-silver complex thermosensitive hydrogel. Methods There were 4 groups: group A (containing 1 ×10-5 chitosan-nano-silver complex thermosensitive hydrogel), group B (containing 5 ×10-6 chitosan-nano-silver complex thermosensitive hydrogel) , group C ( containing 2 ×10-6 chitosan-nano-silver complex thermosensitive hydrogel) , group D ( chitosan thermosensitive hydrogel ) .The antibacterial activity of the samples against six kinds of gram-negative bacteria, one kind of gram-positive bacterium, three kinds of fungi were measured by bacteriostatic circle.The cytocompatibility of the extraction to NIH-3T3 cells was studied by SRB. Results The antibacterial activity enhanced with the increasing of nano silver concentration in chitosan-nano-silver complex thermosensitive hydrogel, whose antibacterial activity was better than chitosan thermosensitive hydrogel; its extraction has no cytotoxicity, thus showed good cytocompatibility. Conclusion The chitosan-nano-silver complex thermosensitive hydrogel is a potential novel wound dressing.
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Objective To study the effect of nano-silver active carbon fiber dressings on wound healing in bedsore wound animal models. Methods Adult SD rats were used and bedsore wound models were made on their back; the animals were then randomly divided into 5 groups (n=10) according to different materials of the wound dressing and treatment. Groups were treated with nano-silver active carbon dressings, nano-silver dressings, active carbon dressings, Vaseline chlorhexidine dressings, or blank control. The wound healing situation, contents of angiogenic factors and inflammatory factors in wound tissues were compared among the 5 groups. Results Wound healing time and the healing rates were different among the 5 groups, with the healing time of rats in nano-silver active carbon dressing group being significantly shorter than those in the other 4 groups (P<0.05). On the 3rd, 7th, 14th and 21st days after bedsore wound modeling, the healing rates of nano-silver active carbon dressing group were significantly higher than those of the other 4 groups (P<0.05). The levels of angiogenesis factors and inflammatory factors were different in wound tissues of five groups, with the contents of VEGFA, VEGFB and VEGFC mRNA in nano-silver active carbon dressing group being significantly higher and the contents of TNF-α, IL-2 and IL-8 mRNA being significantly lower than those of the other 4 groups (P<0.05). Conclusion The prepared nano-silver active carbon fiber dressing can help to improve pressure ulcer wound healing, relieve wound inflammation, and promote angiogenesis in the wound; it may serve as an ideal material for treating bedsore wound.
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16 standered acrylic resin blocks with silicone resilient denture liner(10 mm ×8 mm ×3 mm)incorporated with nano-silver par-ticles at 5% (m/m,by dry wet)in-between were prepared.8 blocks were immersed in distilled water for 24 h at 37 ℃ as the controls (group 1).Another 8 were thermocycled for 4 000 cycles(group 2).16 acrylic resin bars were thermal cycled for 4 000 cycles.Then they were processed exactly as the control group (group 3).Tensile bond strength of the specimens was measured by a universal testing machine. The bond strength values(MPa)of group 1,2 and 3 were 2.683 ±0.435,2.179 ±0.633 and 1.460 ±0.566 respectively(group 1 vs 2,P>0.05;group 3 vs 1 or 2,P<0.05).The failure mode of the blocks in group 1 and 2 was mainly cohesive failure,in group 3 adhesion fail-ure.
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Objective To obserVe the effect of recombinant human granulocyte∕macroPhage colony stimulating factor ( rhGM_CSF) and nano_silVer as treatment for skin with deeP II degree burn. Methods DeeP II degree burn Wistar rat model was established. The rats were randomly diVided into three grouPs,Petrolatum treatment grouP (grouP A,n=30),nano_silVer treatment grouP (grouP B,n=30),and rhGM_CSF treatment grouP (grouP C,n=30). The Pathological changes of wound of the three grouPs were obserVed 1,4,7,10,14 and 21 days after the treatment. The concentration of VEGF in serums was measured with ELISA. The leVels of HIF_1α mRNA exPression were detected by RT_PCR. Results On day 10, neoVascularization deVeloPed in grouPs A, B and C. Healing rate of the wound was the highest in grouP C, lowest in grouP A, with significant differences among the three grouPs on day 14 and day 21 (P<0. 05). VEGF leVel Peaked on day 14 in grouP A,and on day 10 in grouPs B and C. There were significant differences in VEGF leVel on day 1 between grouP A and grouPs B,C,on day 7 between grouP A and grouP C,on day 10,14 and 21 among the three grouPs (P<0. 05),but no significant differences on day 4 among the three grouPs. Conclusion rhGM_CSF and nano_silVer treatment can accelerate neoVascularization of wound,and rhGM_CSF is better than nano_silVer.
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Objective To observe the effect of recombinant human granulocyte/macrophage colonystimulating factor (rhGM-CSF) combined with nano-silver for deep burn degreen Ⅱ. Methods The burn model were done with Wistar rats. They were randomly divided into four groups , group A (n = 30): petrolatum treatment, group B(n = 30): nano-silver treatment, group C(n = 30): rhGM-CSF treatment, and group D(n =30): rhGM-CSF combined with nano-silver treatment. The healing rates of the four groups were observed on postburn day 1, 4, 7, 10, 14, 21. Meanwhile the levels of VEGF and EGF in serums were measured with ELISA. Results All groups started to heal on postburn day 10. Group A had inflammation obviously , and group D moderately. There were significant difference in the healing retes on postburn day 10 , 14, 21 between four groups (P < 0.05). The level of VEGF in group A peaked on postburn day 21 (25.76 ± 1.46)pg/mL, but the levels of VEGF in group B, group C and group D peaked on postburn day 14[(29.73 ± 1.58)pg/mL, (38.91 ± 2.38)pg/mL, (43.54 ± 1.28)pg/mL]. On postburn day 4, 7, 10, 14, 21, there were significant difference(P <0.05). The level of EGF peaked on postburn day 21 in all groups [(0.72 ± 0.14)ng/mL, (0.93 ± 0.13)ng/mL, (1.18 ± 0.16)ng/mL, (1.50 ± 0.15)ng/mL]. There were significant difference on postburn day 7, 10, 14, 21 between four groups (P < 0.05). Conclusions rhGM-CSF combined with nano-silver treatment could promote wound healing, and be better than rhGM-CSF and nano-silver singly.
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Objective: To synthesize and characterize Sanguisorbae Radix/nano-silver composites by reduction of silver nitrate solution using Sanguisorbae Radix as reducing agent and dispersant. Methods: Taking the absorbance of UV-visible spectroscopy of Sanguisorbae Radix/nano-silver composites as index to study the influence of different factors, such as extracting time of Sanguisorbae Radix powder, reaction temperature of synthesis, volume of Sanguisorbae Radix extract, and concentration of AgNO3, on the formation of nano-silver composites and to optimize the conditions. TEM, XRD, FT-IR, and DLS could be used to characterize the physicochemical properties of Sanguisorbae Radix/nano-silver composites. Results: The optimum conditions were as follows: the boiling time of Sanguisorbae Radix powder was 15 min, the volume ratio of 0.1 g/mL Sanguisorbae Radix extract and 1 mmol/L AgNO3 was 1:10, the resultant temperature was 25 °C, and the reaction time was 1 h, the Sanguisorbae Radix/nano-silver composites obtained were approximately spherical in shape with the mean size about 21 nm in good uniformity and stability. Conclusion: The preparation of Sanguisorbae Radix/nano-silver composites is stable and feasible.
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White rot, which is caused by Sclerotium cepivorum, is a lethal disease affecting green onions. Three different types of nano-silver liquid (WA-CV-WA13B, WA-AT-WB13R, and WA-PR-WB13R) were tested in several different concentrations on three types of media to assess their antifungal activities. Results from in vitro experiments showed that all three of the nano-silver liquids had more than 90% inhibition rates at a concentration of 7 ppm. Greenhouse experiments revealed that all of the nano-silver liquids increased biomass and dry weights, and there were minimal changes in the population of various bacteria and fungi from the soil of greenhouse-cultivated green onions. In addition, a soil chemical analysis showed that there were minimal changes in soil composition.
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Humans , Bacteria , Biomass , Fungi , Onions , Soil , Weights and MeasuresABSTRACT
Objective The various influencing factors in the process of nano-silver preparation were studied in order to prepare nano-silver that has uniformity particle size distribution and good crystallinity. Methods Through the method of liquid reduction at room temperature,the nano-silver powders were prepared directly using silver nitrate as raw material,water as the reactive medium,polyvinylpyrrolidone(PVP) as protecting agent and ammonium formate as reducing agent. By means of EDS and TEM(transmission electron microscopy),the prepared silver particles were characterized. The various influencing factors in the process of preparation were also discussed. Results With the increasing concentration of AgNO3,the particle diameter of nano-silver changed obviously. When the concentration of silver nitrate was 0.25-0.30 mol/L,the size of product is the smallest. With the increasing concentration of reductant,the diameter of nano-silver decreased gradually. While at the concentration of 0.70 mol/L HCOOH,the average diameter of nano-silver is not more than 10 nm. Smaller and more well-distributed silver powder could be prepared at ratio of concentration of PVP to AgNO3 with the value of 1.5-1.0,at which PVP presented effective protection. Conclusions This method can prepare particle of nano-silver which revealed well dispersed and uniform size. The process is stable and reliable,easy to operate,high yields and suitable for industrial production.