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第5卷第6期 纳米 科技 No.6 2008年12月 Nanoseience& Nanotechnology December 20HD8 Preparation of Au Nanoparticles in Presence of Low Generational TEG..—- PAMAM Dendrimer in Aqueous Solution MAO Yong.WU Jiang-yu.GUO Dong Materials Science&Engineering.Wuhan Institute of Technology, Wuhan 430074, China) Abstract:Au nanoparticles were prepared through the restoration of HAuC14 with NaBH4 in the presence of low generational TEG—PAMAM dendrimer in aqueous solution.UV—Vis absorption spectra. 一1R spectra and transmission electron microscopy fTEM1 were used to study the preparation process and.aspect、of the Au nanoparticles obtained.The results show that the diameters of Au nanoparticles are 3.5±0.4 nm.2.6±1.6 nm and 2.88±1.33 nm with the molar ratio of HAuCl√G1.5 of 2:1,1:1, and l:2.respectively.The formed Au nanoparticles are stably stored for months at room temperature. Keywords:triethylene glycol;low generation;template;Au nanoparticles 水溶液中低代TEG—PAMAM树形分子存在下金纳米颗粒的制备 毛勇, 吴江渝, 郭栋 (武汉工程大学材料科学与工程学院, 湖北 武汉430074) 摘要:在水溶液中低代TEG—PAMAM树形分子存在时,用NaBH 还原HAuCI 制备出金纳米颗粒。用紫外可见吸 收光谱(uv—Vis),红外光谱(盯一1R)和透射电子显微镜(TEM)对所制备的金纳米颗及其制备过程进行了表征,实验结 果表明,以低代树形分子为模板,当HAuCI 与TEG—PAMAM物质量的比分别为2:1,l:1和1:2时,所制的金纳米颗 粒的粒径分别为3.5+0.4nm.2.6+-1.6nm和2.88_+1.33nm,并且可在室温下储存数月。 关键词:三乙二醇;低代树形分子;模板;金纳米颗粒 中图分类号:TB34 文献标识码:A 文章编号:1812—1918(2008)06—0023—05 O IntrOductjOn catalyst carrier.imaging material and SO on【 J 4】 Preparation of controllable size and shape of the Noble metal nanoparticles,especially'Au metal nanoparticles is a challenging subject since nanopartMes have attained significant attention the particle size,shape and size distribution,which ()wing to their unique optical,electronic,magnetic strongly depend on the preparation process and and catalytic properties that can lead to a wide experiments followed, are veryimportant in . variety of potential applications in semiconductors, determining the applications of the nanoparticles. Thus far,kinds of strategies have been extensively 收稿日期:2008—08—29 第5卷第6期 2008年12月 纳米加工工艺 Nano—processing Technique V0l-5 No.6 December 2008 investigated to produce the Au nanoparticles with fascinating structures and functionalities,Particularly, the template method is increasingly concerned because it can conIro】the size,shape,and size distributions of Au nanoparticles efficiently.As indicated in abundant trihydrate (HAuC14 3H2O),and sodium borohydide (NaBH4)were purchased from Sinopharm Chemcial Reagent Co.Ltd and were used without further puriicatfion.Ethylenediamine and methyl acrylate were distilled prior to use.Distilled water was used as the solvent during the preparation process of Au nanoparticles. reports elsewhere,linear polymers,suffactant and dendrimers have been used as templates for the preparation of Au nanoparticles【 H81. Dendrimers are a new class of macromolecules that consist of a central core,regularly branched building blocks and a number of terminal groups and easily find their applications in medical chemistry,host-guest chemistry and catalytic chemistry 【 -[101.In some recent papers,poly (amidoamine) (PAMAM)dendrimer of high generations(G5一G 1 0)has been successfully used as the templates for the preparation of metal nanopartieles by taking advantage of their highly branched structure with multiple cavities I9Hl2 1.As a matter of fact,the synthesis of hi【gh generation dendrimer is complicated。dimcult and time— consuming.Dendrimers of lower generations, however,are easily prepared and tend to exist in relative open forms providing reactive sites at the periphery of the dendrimer molecules [131-{fs]. Therefore,It is very interesting to study the template capability of lower generational dendrimers for preparation of metal nanoparticles. In this work, low generational PAMAM dendrimer(G 1.5)with TEG core was developed and investigated as a template to produce Au nanoparticles in aqueous solution.We studied the role of the dendrimer template during preparation of Au nanoparticles by Fourier transform infrared rfY1 一 IR)spectroscopy.The formed Au nanoparticles solution was characterized by UV—Vis absorption spectra and transmission electron microscopy(TEM). 1 Experimental 1.1 Materiais Triethylene gly col,hydrogen tetrachloroaurrate 24 1 H NMR spectra were measured at 300 MHz on a Varian Mercury——VX300 spectrometer using TMS as an internal reference.UV-vis absorption spectra were recorded with a UV -1 8 spectr0ph0tometer(Tianjin Tuopu Insturment Co., China).Fourier transform infrared spectra were measured on Nicolet Impact 420 F-F-IR spectrometer.Transmission electron microscopy (TEM)of Au nanoparticles was taken with a.Hitachi mode H一600 apparatus(Nicolet Co. USA).The mean particle diameter was calculated from the TEM images by using the software Image J. 1.2 Synt hesis of low generational TEG—- PAMAM dendrimer The synth esis of methyl ester terminated poly (amidoamine1 dendrimer G 1.5 with a triethylene glycol core was described simply as follows(shown in scheme 1 1.A 1.4一Dioxane solution of triethylene glycol was treated with 1 0——fo.1d excess of acrylonitrile to give the desired dinitrile. Concentrated sulfuric acid was added to the methanoI solution of the obtained dinitrile to give the desired diester.The obtained di ester was dissolved in methanol and added dropwise to the 20-fold excess of ethylenediamine to give the zero generation of amine terminated GO.The excess of ethylenediamine and solvent was removed bv distilling under vacuum.A methanolie solution of the resultant GO was treated with eight molar equivalents of methyl acrylate to give the desired half generation GO.5.The excess of methyJ acrylate and solvent was removed under vacuum.Repetitions fo the Michae】addition reaction and amidation 第5卷第6期 纳米科技 2008年12月 No.6 Nanoscience&Nanotechnology December 2oO8 reaction yielded the ester terminated G1.5.盯IR added,a plasmon band in rang of 500—530 nm was (KBr,cm ):3308.58,l735.17,1647.07、1550.40 appeared, confirming the formation of Au and 1 357.87.1 H—NMR fCDCI3):8 3.68 f24H. nanoparticles.The kmax for this characteristic band OCH3),3.62(1 2H,OCH2CHz0),3.76(4H,OCH2), 0f Au nanoparticles was 522 nm【 61-[。 ,5 1 5 nm,and 2.75 (28H,CH2C=O),3.30(12H,NHCH2),2.50 518 nm,with the molar ratio of HAuC1JG1.5 of 2:1. (12H,CH2N),2.521(24H,NCH2). 1:1,and 1:2,respectively.In addition,the solution 1.3 Preparation of Au nanoparticles color changed from colorless into reddish brown, giving another evidence for the presence of Au The HAuC14 solution f1 mmoUL1 was added to nanoparticles,which were stably stored for months G1.5 solution(1 mmol/L)at molar ratios of 2:1,l:1 at room temperature without macroscopic and 1:2.respectively.The mixed solution was precipitation.In the case of G1.5 free system,the vigorously stirred for 1 0 min at room temperature for sufficient complexation..The eomplexation solution was then reduced by addition of NaBH4 solution(1 0 哪嘴嘶喵咖啮.a。u 凸JC西呦嘴咖!^ 詈哪嘶 mmol/L in 0.6 mol/L NaOH).The color of solution immediately changed from colorless to reddish brown,indicating the formation of colloidal Au.The process was shown in Fig.1. 2 Result and discussion As shown in Fig.2,the UV—vis spectrum of HAuC14 solution revealed a strong absorption band Fig.2 UV~vis absorption spectra of HAuC14 solution before at 325 nm assigned as ligand——to——metal charge reduction and Au nanoparticles solutions at diferent molar transfer (LMCT)of AuC14—1.After NaBH4 was ratios(HAuC14/GI.5) \cN Ho ,^o/,jvOH Nc/,、、一,o o\//\Conc.H2S04 0 cN ~。小。 。\/ 。\ 2 KOH 2 MeoH 0● 0H /\,NH H2H2N/\/N N/\/ 。。  。o  。v oV j \/、NH2NH2 MeoH 0‘。0 3 Steps ~{: 。 。 。 ;{一N 0 0 Fig.1 Synthesis ofthe tri(ethylene glyco1)derived PAMAM G1.5 第5卷第6期 2008年12月 纳米加工工艺 Nano-processing Technique Vo1.5 No.6 Deeember 2008 dark precipitates appeared within several minutes. These phenomena showed that the synthetic G 1.5 the size of the Au nanoparticles formed,according to the related UV-vis spectra in Fig.2 Furthermore we investigated the interactions between G1.5 and Au nanoparticles through FT—IR measurement.Fig.4 shows the丌-IR spectra of dendrimer could be developed as a potential template and stabilizer for the preparation of Au nanoparticles. Fig.3 shows the TEM images of Au G 1.5 and G 1.5/Au nanocomposites.The amide I and II bands at 1647.07 cm一 and l550.40 em一‘shit to f1637.76 cm—and 1567.71 cm-1.The methyl ester band at 1735.1 7 cm~disappeared,while a new absorption band appeared at 1 406.28 em一‘which could be assigned to sodium carboxylates because of the degradation of G 1.5 in alkaline environment. Based on the varieties of the bands,it could conclude that Au nanoparticles interacted strongly with the amide groups of G1.5,resulting in the formation of more stable Au nanoparticles. nanoparticles produced in the aqueous solution. Although most particles were isolated,some aggregation appeared indicating the restricted stabilization ability of the low generational dendrimer.The average sizes of the nanoparticles Were calculated as 3.5 4-0.4 nm,2.6±1.6 nm and 2.88±1.33 nm at the molar ratio(HAuCIn/G1.5)of 2:1,1:1,and 1:2,respectively.Meanwhile,we found that the hmax of the characteristic plasmon resonance band of Au nanopartieles increased with Dimneter/nm INameter/nm Diameter/nln Fig.3 TEM image and size distribution ofAu nanoparticles:(a),0o)and c)at the molar ration dendrimer HAuCL/G 1.5 of2:l,1:1,and 1:2 after reduction respectively 第5卷第6期 2008年12月 4000 350() t.0fm 2500 2(J【x】 l 500 1000 500 Wa、cnumbers f crll—I] Fig 4 FT—IR spectra of(a)G1 5,and(b)G1.5/Au nanocomposite 3 Conclusions 吣 一 In this work.Iow generational TEG—PAMAM 米洮 dendrimer was synthesized and used as a template 科№ and stabilizer to prepare Au nanoparticles by the 技-reduction with NaBH4 in aqueous solut引 蚕 ion.The UV-vis absorption spectra confirm the formation of Au nanoparticles.The TEM images assess that the size of Au nanopartieles are 3.5±0.4 nm.2.6±1.6 Hm and 2.88±1.33 tim at the molar ratios fHAuCld G1.51 of 2:1,1:1,and 1:2,respectively.The FT-IR spectra SHOWS the interactions between formed Au nanoparticles and the amide groups of G1.5.Further characterization of obtained Au nanoparticles and detailed analysis of interactions between dendrimer molecules and Au nanoparticles are ongoing. 4 Acknowledgement We are grateful to Natural Science Foundation 0f Hubei Province.China.Education Bureau of Hubei Province,China (No.D2008 1 50 1)and Natural Science Foundation of China fNo. 2050 1 0 1 6)for financial support.Wuhan Institute of Technology is also gratefully acknowledged. 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