Synthesis of self assembled noble metal nanoparticle chains using amyloid fibrils of lysozyme as templates

Nanomaterials and Nanotechnology ARTICLE Synthesis of Self-assembled Noble Metal Nanoparticle Chains Using Amyloid Fibrils of Lysozyme as Templates Regular Paper Ziming Xu1#, Lili Li1#, Hou Li1 and Faming Gao1* Key Laboratory of Applied Chemistry, Department of Applied Chemistry, Yanshan University, Qinhuangdao, P R China These authors contributed equally to this work *Corresponding author(s) E-mail: fmgao@ysu.edu.cn # Received 10 November 2015; Accepted 21 December 2015 DOI: 10.5772/62182 © 2016 Author(s) Licensee InTech This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited Abstract Introduction We reported a facile method for preparing self-assembled noble metal nanoparticle chains by using lysozyme amyloid fibrils as a biotemplate in an aqueous environ‐ ment The nanoparticle chains of gold (AuNPCs), palladi‐ um (PdNPCs), platinum (PtNPCs) and rhodium (RhNPCs), which are lysozyme fibrils coated by gold, palladium, platinum and rhodium nanoparticles, can be fabricated by simply reducing the corresponding metal salt precursors using NaBH4 Under the same molar ratio between salt precursors and fibrils, two types of morphologies of highyield AuNPCs (thin- and thick- AuNPCs) were synthesized as a result of adjusting the fibrosis time and temperature in the final stage Abundant PdNPCs with a length of several micrometres intertwisted with each other to form PdNPC networks The growth of RhNPCs started from the inner surface of the fibrils and gradually spread to the whole fibre as superabundant rhodium nanoparticles (RhNPs) bound to the fibrils Finally, PtNPCs at different growing periods were presented The nanostructures were investigated by transmission electron microscope, UV-visible spectrosco‐ py, fluorescence spectroscopy, energy-dispersive X-ray spectroscopy and atomic force microscope Noble metal nanoparticles, with their unique electrical, optical and magnetic performance and various potential applications, have become one of the popular fields in nanoscience because of their interesting shape-dependent and size-dependent physical and chemical properties [1] To optimize and extend the morphology of noble metal nanoparticles, biological self-assembled methods have been developed due to the following advantages of biomolecules, which are: (1) the charged and chemically reactive moieties with amine and carboxyl groups attract‐ ing with other chemical molecules, (2) their natural substrate-specific affinity assembling and aligning the biomolecule in a specific pattern, (3) transforming sub‐ strates into other forms for the enzymatic activity of biomolecules, which can be employed to synthesize nanostructured materials [2] Up till now, numerous studies on the synthesis of metal nanoparticles have been achieved through the use of biological self-assembled methods Mudalige Thilak Kumara and colleagues have effectively yielded metal nanoparticles and nanotubes on bioengineered Flagella scaffolds [3] Longgai Zhang and colleagues have synthesized ultrathin platinum nanowires using insulin fibrils as sacrificial templates [4] In our study, we exploited self-assembled amyloid fibres from lysozyme, Keywords Self-assembled, Nanoparticle Chains, Lyso‐ zyme Amyloid Fibrils, Metal Nanomater Nanotechnol, 2016, 6:4 | doi: 10.5772/62182 which exists extensively in nature, as biotemplates to synthesize noble metal nanoparticle chains To date, amyloid fibrils, which share a common β-sheet rich structure [5], have been extensively studied both theoretically and experimentally They are known for their association with conformational diseases caused by protein misfolding, such as Alzheimer’s disease, late onset diabetes and Parkinson’s disease [6-9] Nevertheless, amyloid fibrils have the outstanding advantages men‐ tioned above, making them ideal materials and compo‐ nents for advanced nanotechnology Therefore, the advantage of the spontaneous fibrillation mechanism of amyloid fibrils under conditions of low pH and high temperature [10] can be employed to control the nano‐ structure of metal nanoparticles Lysozyme, a type of amyloid protein used in this research, is composed of 129 amino acids It is a monomeric globular protein with a high percentage of lysine and arginine [11], which was possibly the main action group of the predom‐ inantly electrostatic interactions [12] Herein, noble metal nanoparticle chains were synthesized by a facile method in which lysozyme fibrils were exposed to gold, palladium, platinum and rhodium precursors separately By adjusting the experimental conditions, different morphologies of gold nanoparticle chains (AuNPCs), palladium nanoparti‐ cle chains (PdNPCs), rhodium nanoparticle chains (RhNPCs) and platinum nanoparticle chains (PtNPCs) were presented Materials and Methods 2.1 Materials Lysozyme from hen egg white (HEWL) was supplied by Beijing Biodee Biotechnology Co., Ltd Potassium chloro‐ platinate (KPtCl6) and palladium chloride (PdCl2) were purchased from Tianjin Chemical Reagent plant (Tianjin, China) Rhodium chloride (RhCl3), chloroauric acid (HAuCl4) and sodium borohydride (NaBH4) were obtained from Chengdu West Chemical Co., Ltd (Chengdu, China) Magnesium chloride (MgCl2) was purchased from Tianjin Fengchuan Chemical Reagent Technology Co., Ltd (Tianjin, China) Hydrochloric acid (HCl) was bought from Gu’an Chemical plant (Langfang, China) Milli-Q reagentgrade water was home-prepared 2.2 Methods quently, the reducing agent of excess fresh NaBH4 (5 mM) solution was injected into the mixture, drop by drop In the contrast experiment, we changed the experimental condi‐ tions and the fibrosis time (73 h), and heated the mixture after reducing it to improve the quantity of gold NPs coated on the HEWL fibrils 2.2.2 Fabrication of palladium nanoparticle chains (PdNPCs) HEWL powder was dissolved with 0.1 M MgCl2 and 25 mM HCl mixed solution The target concentration was mg/mL It was then placed in a thermostatic metal bath at 70 ℃ for 24 h The HEWL fibrils were not completely mature at that moment Next, the 2.5 mM PdCl2 solution was added to the HEWL fibrils, followed by incubation for 48 h at room temperature Subsequently, the reducing agent of excess fresh NaBH4 (5 mM) solution was injected into the mixture, drop by drop 2.2.3 Fabrication of rhodium nanoparticle chains (RhNPCs) HEWL powder was dissolved into 25 mM hydrochloric acid (HCl) to form mg/ml HEWL-HCl solution To induce the fibrosis of lysozyme, the sample was heated without disturbance in a thermostatic metal bath at 70 ℃ for 48 h Then 2.5 mM rhodium chloride was added into the HEWL fibrils and incubated for 24 h Finally, the sample was also reduced with excess fresh NaBH4 (15 mM) solution, drop by drop 2.2.4 Fabrication of platinum nanoparticle chains (PtNPCs) HEWL powder was dissolved with 0.1 M MgCl2 and 25 mM HCl mixed solution The target concentration was mg/mL It was then placed in a thermostatic metal bath at a constant 70 ℃ for 60 h Subsequently, the 2.5 mM K2PtCl6 solution was added to the HEWL fibrils, following incuba‐ tion for 24 h at room temperature Finally, the sample was also reduced with excess fresh NaBH4 (5 mM) solution, drop by drop A summary of these four samples and the conditions used for the synthesis are presented for reference in Table below Sample HEWL incubation HEWL Heating time Metal incubation AuNPCs Nanomater Nanotechnol, 2016, 6:4 | doi: 10.5772/62182 (70 ℃) time 25 mM HCl 77 h 24 h 24 h 48 h PdNPCs 25 mM HCl+0.1 M MgCl2 2.2.1 Fabrication of gold nanoparticle chains (AuNPCs) HEWL powder was dissolved into 25 mM hydrochloric acid (HCl) to form mg/ml HEWL-HCl solution To induce the fibrosis of lysozyme, the sample was heated without disturbance in a thermostatic metal bath at 70 ℃ for 77 h Then mM chloroauric acid and 25 mM HCl mixture were added to the mature fibrils After homogeneous mixture, it was incubated at ambient temperature for 24 h Subse‐ solution RhNPCs 25 mM HCl 48 h 24 h PtNPCs 25 mM HCl+0.1 M 60 h 24 h MgCl2 Table Synthesis conditions for four different metals Transmission electron microscope (TEM) images of the metal nanoparticle chains were observed by using a Hitachi model HT-7700 instrument with an accelerating voltage of 100 kV TEM samples were prepared by placing a droplet of the sample solution onto copper grids coated with amorphous carbon film and dried at room tempera‐ ture [13] The ultraviolet-visible (UV-vis) absorption spectra of AuNPCs were measured by a WFZ-26A UV– vis spectrophotometer The fluorescence of AuNPCs under the Xe laser excitation was measured by a Hitachi model F-7000 instrument The structure of metal nanopar‐ ticle chains was examined by selected area of electrical diffraction (SAED) and high-resolution transmission electron (HRTEM) on a JEM model 2010 instrument To determine the component elements of RhNPCs, energydispersive X-ray spectroscopy (EDS) analysis was per‐ formed on the HT-7700 instrument spacings in the HRTEM image of the thick-AuNPCs were 0.2031 nm and 0.2375 nm, which correspond with the (200) and (111) lattice planes respectively in the face-centred cubic Au b a e 125nm d 0.2348nm 1um 2um Results and discussion c nm g 3.1 Fabrication of gold nanoparticle chains (AuNPCs) Abundance of AuNPCs, which were determined by transmission electron microscopy (TEM), were highly yielded by a facile method, as shown in Figure 1a The average length of AuNPCs was several micrometres and the longest reached to 12 µm For further observation, a randomly selected AuNPC with a length of 6.8 µm is displayed in Figure 1b, which shows the mature fibrils coated with a few AuNPs For convenience, the AuNPCs with a few AuNPs are called thin-AuNPCs for short Figure 1c shows a higher magnification image of the randomly selected thin-AuNPC, which exhibits the double helix structure The structure of thin-AuNPCs was investigated by means of SAED patterns (Figure 1e), whose continuous rings from inner to outer are accordant with the (111), (200), (220) and (311) planes of the expected face-centred cubic Additional structural characterizations of thin-AuNPCs were performed using HRTEM, which indicates their crystalline nature The HRTEM image showing different crystal planes is shown in Figure 1d The smallest spacing between two crystal planes is 0.2348 nm, corresponding to the (111) lattice spacing of Au To increase the quantity of AuNPs attaching to the HEWL fibrils, we changed the experimental conditions, fibrosis time and temperature in the final stage, instead of changing the molar ratio [14] between salt precursors and HEWL fibrils The AuNPCs obtained in these conditions are called thick-AuNPCs, as exhibited in Figure 1f The longest of the thick-AuNPCs was up to 15 µm Similarly, we randomly selected one with a length of 9.3 µm, as indicated in Figure 1g, which was magnified (Figure 1h) From this, a large quantity of AuNPs bound to the mature fibrils were observed, compared with the thin-AuNPCs mentioned above Figure 1h also indicated the helix structure of thickAuNPCs For comparison with the structure of thinAuNPCs, thick-AuNPCs were also studied by means of SAED patterns (Figure 1j), the result of which correspond‐ ed to that of the thin-AuNPCs Nevertheless, the lattice j h 20nm i 0.2031nm 0.2375nm 2µm 1µm nm Figure TEM images of (a) thin-AuNPCs and (f) thick-AuNPCs; (b) low and (c) high magnifications of a typical single thin-AuNPC; (g) low and (h) magnifications of a typicalof single thin-AuNPC; low and (h) highhigh magnifications of aimages typical high magnifications a typical single(g) thick-AuNPC; resolution of (d) thin-AuNPCs and (i) thick-AuNPCs; SAED pattern of (e) thinsingle thick-AuNPC; high resolution images of (d) thin-AuNPCs and (i) thick-AuNPCs; SAED AuNPCs and (j) thick-AuNPCs Figure TEM images of (a) thin-AuNPCs and (f) thick-AuNPCs; (b) low and (c) high pattern of (e) thin-AuNPCs and (j) thick-AuNPCs Figure UV-visible recorded Figure 22 shows shows thethe UV-visible absorptionabsorption spectra recordedspectra from thin-AuNPCs and from thin-AuNPCs and thick-AuNPCs It is known that the thick-AuNPCs It is known that the main feature of the absorption spectra for metallic main feature of the absorption spectra for metallic nano‐ particles is of the surface plasma resonance (SPR) band [15] As can be seen, both thin-AuNPCs and thick-AuNPCs displayed only a single absorption band attributed to the collective dipole oscillation (surface plasma resonance, SPR) at 530 nm due to the elongated structure Hence, it can be confirmed that the AuNPCs we prepared were spheri‐ cal-like [16] nanoparticles arranged into elongated NPCs, corresponding to the TEM above Furthermore, the peak of thick-AuNPCs was stronger in comparison with that of thin-AuNPCs, which might be attributed to the abundance of AuNPs bound to the HEWL fibrils The colours of the thin-AuNPC and thick-AuNPC solutions were pink and burgundy (inset), respectively The fluorescence of thin-AuNPCs and thin-AuNPCs with the concentration of 0.17 mM was further investigated, as displayed in Figure For nanometre-size or sub-nanome‐ tre-size gold particles, both small size effect and surface effect should be considered and the emission intensity and band position are sensitive to the morphology of the nanoparticles [17] As can be seen in Figure 3, the fluores‐ Ziming Xu, Lili Li, Hou Li and Faming Gao: Synthesis of Self-assembled Noble Metal Nanoparticle Chains Using Amyloid Fibrils of Lysozyme as Templates can be confirmed that the AuNPCs we prepared were spherical-like16 nanoparticles arranged into elongated NPCs, corresponding to the TEM above Furthermore, the peak of thick-AuNPCs was stronger in comparison with that of thin-AuNPCs, which might be attributed to the abundance of AuNPs bound to the HEWL fibrils The colours of the thin-AuNPC and thick-AuNPC solutions were pink and burgundy (inset), respectively a b c Absorbance 1.2 tive A high-magnification image of a typical single PdNPC selected randomly is shown in Figure 4b It indicates that the PdNPs coated on the HEWL fibrils grew along the double helix structure In addition, the selected-area electron diffraction (SAED) pattern recorded from a few PdNPCs was performed (Figure 4c) The values in the SAED pattern correspond to the (220) and (311) planes of the expected face-centred cubic Pd structure, confirmed by the crystallinity of PdNPCs A high-resolution TEM (HRTEM) image taken from an individual PdNPC elabo‐ rates a well-defined lattice spacing of 0.2011 nm (Figure 4d), which corresponds to the (200) lattice plane of palla‐ dium PdNPCs thin-AuNPCs thick-AuNPCs hydrochloric acid d 0.8 e 0.4 0.0 200 300 400 500 600 700 800 Wavelength(nm) The UV-vis spectraofof(a) (a) thin-AuNPCs thin-AuNPCs and (b) thick-AuNPCs The insert shows the Figure Figure The UV-vis spectra and (b) thick-AuNPCs The insert shows the samples of (d) thin-AuNPCs samples of (d) thin-AuNPCs and (e) thick-AuNPCs and (e) thick-AuNPCs 17 and band position are sensitive to the morphology of the nanoparticles As can be seen in Figure The fluorescence of thin-AuNPCs and thin-AuNPCs with the concentration of 0.17 mM was 3, the fluorescence peakwas was displayed in the blue-violet wavelength region This may be mainly cence peak displayed in the blue-violet wavelength a b further investigated, as displayed in Figure For nanometre-size or sub-nanometre-size gold Fluorescence Intensity(a.u.) region This may be mainly attributed to some gold clusters particles, small sizeformed effect andin surface effect should be considered and the emission attributed to some goldboth clusters a certain percentage because of the intensity HEWL fibril formed in a certain percentage because of the HEWL fibril (amino residues HEWL groups’groups’ (amino acid residuesacid in HEWL fibril) in confined spacefibril) effect confined These sub-nm Au space effect These sub-nm Au nanoclusters [18 - 19] are too 18-19 nanoclusters too small to have a continuous densityof of states, states, butbut ratherrather show quantum small toarehave a continuous density show quantum confined electronic transitions and thus are confined electronic transitions and thus are fluorescent As indicated in Figure 3, the fluorescence fluorescent As indicated in Figure 3, the fluorescence spectra of thick-AuNPCs centred at 412 nm and 440 nm waswith that spectra of thick-AuNPCs centred at 412 nm and 440 nm was blueshifted in comparison blueshifted in comparison with that of thin-AuNPCs of thin-AuNPCs 425 and nm and nm because because of of thethe smaller Au cluster centred centred at 425atnm 460460nm smaller Au size of cluster size of thick-AuNPCs The fluorescence intensity of thick-AuNPCs The fluorescence intensity of thick-AuNPCs was stronger than that of thick-AuNPCs was stronger than that of thin-AuNPCs due to the higher load of gold nanoclusters on the HEWL fibrils thin-AuNPCs due to the higher load of gold nanoclusters on the HEWL fibrils c d (311) (220) 0.2011nm 3000 nm thick-AuNPCs thin-AuNPCs 2500 Figure (a) and (b) high-magnification images PdNPCs; Figure (a) low-lowand (b) high-magnification TEM imagesTEM of PdNPCs; (c) of SAED pattern (c) of SAED pattern of PdNPCs; (d) HRTEM image of PdNPCs 2000 PdNPCs; (d) HRTEM image of PdNPCs 1500 3.3 Fabrication of rhodium nanoparticle chains (RhNPCs) 1000 Different morphologies of RhNPCs are shown in Figure surface of HEWL fibrils (Figure 5a), which were heated for 96 h The rhodium RhNPCs mainly The RhNPCs grow on the inner surface of HEWL fibrils (Figurealong 5a), which were for5a.96 h The rhodium germinated a thread, as displayed in theheated inset of Figure However, when superabundant RhNPCs mainly germinated along a thread, as displayed rhodium nanoparticles (RhNPs) bound to the HEWL fibrils, they overgrew the HEWL fibrils in the inset of Figure 5a However, when superabundant (Figure 5b), whichnanoparticles can be clearly observed in the inset of Figure 5b to The the fibrosis HEWL time was rhodium (RhNPs) bound fibrils, they overgrew the HEWL fibrils (Figure 5b), which adjusted for 72 h to control the morphology of RhNPCs (Figure 5c) The rhodium RhNPCs can be clearly observed in the inset of Figure 5b The fibrosis time was adjusted for 72 h to control the morphology of RhNPCs (Figure 5c) The rhodium RhNPCs became finer and more spindly compared with that in Figure 5b Figure 5d shows the selected area electron diffraction pattern of the RhNPCs, which signifies the polycrystalline nature of the RhNPCs with the spacings corresponding to the (111), (200), (220) and (311) planes 3.3 Fabrication of rhodium nanoparticle chains (RhNPCs) Different morphologies of RhNPCs are shown in Figure The RhNPCs grow on the inner 500 350 400 450 500 550 600 650 wavelength FigureFigure The3.fluorescence spectra of thick-AuNPCs The fluorescence spectra of thick-AuNPCsand andthin-AuNPCs thin-AuNPCs 3.2 Fabrication of palladium nanoparticle chains (PdNPCs) TEM measurements were carried out on the palladium metallized HEWL fibrils The TEM images in Figures 4a and b show the PdNPCs at different magnifications The low-magnification TEM image (Figure 4a) reveals the presence of abundant PdNPCs with length of several micrometres intertwisted with each other to form PdNPC networks The high-yield production of PdNPCs demon‐ strated that the observed features are indeed representa‐ 100nm 500nm Nanomater Nanotechnol, 2016, 6:4 | doi: 10.5772/62182 The chemical composition of RhNPCs was determined by energy-dispersive X-ray spectroscopy (EDS), the result of which is shown in Figure The EDS analysis shows that the became finer and more spindly compared with that in Figure 5b Figure 5d shows the selected area electron diffraction pattern of the RhNPCs, which signifies the polycrystalline nature of the RhNPCs with the spacings corresponding to the (111), (200), (220) and (311) planes b a 100nm 100nm 500nm 1µm d c (311) (220) was unable to be calculated owing to the reticular mor‐ phology [PtCl6]2- nucleates along fibres and grows into chains after it is reduced Initially, immature PtNPCs were mainlines, which absorb redundant platinum nanoparti‐ cles when they continue to grow The AFE image in Figure 7c shows that the longest immature PtNPC was about µm The height of immature PtNPCs was 4.476 nm (Figure 7d) The SAED pattern of PtNPCs in Figure 7f was accord‐ height of immature PtNPCs was 4.476 nm (Figure 7d) The SAED pattern of PtNPCs in Figure 7f ant with the (111), (200), (220) and (311) planes, which was accordant with (111), (200), (220) and (311) planes,of which signified the polycrystalline signified thethe polycrystalline structure PtNPCs structure of PtNPCs (200) a (111) b 100nm 500nm 200nm 200nm Figure TEM images of (a) of low-magnification RhNPCs grown on the inner on surface of HEWL Figure TEM images (a) low-magnification RhNPCs grown the inner surface of HEWL fibrils; (b) low-magnification RhNPCs with more RhNPs; (c) low-magnification RhNPCs with different experiment conditions; (d) SAEDexperiment pattern conditions; of RhNPCs; (inset) high-magnification counterpart of different (d) SAED pattern of RhNPCs; (inset) of high-magnification RhNPCs fibrils; (b) low-magnification RhNPCs with more RhNPs; (c) low-magnification RhNPCs with 8.1n c counterpart RhNPCs d f （311） （220） （200） （111） e The chemical composition of RhNPCs was determined by energy-dispersive X-ray sample contains Rh element with Cu and C signal peaks fromtheand the TEM grid The presence of oxygen, nitrogen spectroscopy result of which is shown in Figure The EDS fibrils analysis shows that the and ofcoming oxygen, (EDS), nitrogen sulphur should be attributed to the HEWL The aluminium and sulphur should be attributed to the HEWL fibrils The 500nm sample contains Rh element with Cu and C signal peaks coming from the TEM grid The presence chlorine peaks cameand from the aluminiumpeaks sheet of TEM andfrom hydrochloric respectively aluminium chlorine came the acid, aluminium sheet of TEM and hydrochloric acid, respectively Figure (a, b) TEM images of PtNPCs at growing different growing periods; (c)PtNPCs; AFE Figure (a, b) TEM images of PtNPCs at different periods; (c) AFE image of image of PtNPCs; (d) the height of PtNPCs subjected to sectioning in positions in c; (e) 3D AFM image of PtNPCs; (f) SAED pattern of RhNPCs (d) the height of PtNPCs subjected to sectioning in positions in c; (e) 3D AFM image of PtNPCs; Cu (f) SAED pattern of RhNPCs In Inthe above discussion, we have demonstrated the wirethe above discussion, we have demonstrated the wire-like assembled structures of gold, like assembled structures of gold, palladium, rhodium and palladium, rhodium and platinum nanoparticles lysozyme-templated amyloid amy‐ fibrils The platinum nanoparticles using using lysozyme-templated loid fibrils The formation mechanism of these four noble formation mechanism of these four noble metals would be similar Here, we give our best guess to metals would be similar Here, we give our best guess to Rh elaborate the possible mechanism of them based on HEWL as aof template, it would elaborate the detailed possible detailed mechanism themhoping based on HEWL as a template, hoping it would guide directions guide directions for future research The 3D structure of a HEWL fibril is a helix of one or more Al for future research The 3D structure of a HEWL fibril is a Cl Cu helix of one or more pairs of protofilaments winding Cu N S O around a hollow core, which seems common to most and possibly all amyloid fibrils [20] When HEWL fibrils co0 10 incubated with the metal solutions, the charged metal ions Energy (keV) could adsorb to the fibrils and form the HEWL-metal ion complexes through weak electrostatic interaction After Figure EDS spectrum of RhNPCs Figure EDS spectrum of RhNPCs subsequently adding the NaBH4, the complexes are 3.4 Fabrication of platinum nanoparticle chains (PtNPCs) reduced to metal nuclei and, with time, the preformed 3.4 Fabrication of platinum nanoparticle chains (PtNPCs) Similar procedures were followed to prepare PtNPCs, which are characterized bymetal seeds grow to form bigger metal nanoparticles on the HEWL fibrils, namely noble metal nanoparticle chains Similar procedures were followed to prepare PtNPCs, transmission electron microscopy and atomic force microscope, as shown in Figure Figures 7a based on HEWL fibrils Therefore, the presence of both which are characterized by transmission electron micro‐ scopy atomic microscope, as shown in length Figure 7.PtNPCsHEWL and weak electrostatic interaction are crucial for the and b showand the TEM images force of PtNPCs at different growing periods The of the formation of metal NPCs However, this weak electrostatic Figures 7a and b show the TEM images of PtNPCs at was apparently growing hundreds of nanometres Figure 7a and itofwas The was length of theinteraction between metal ions and HEWL fibrils varies different periods.inThe length theimmature PtNPCs with the type of metal Moreover, when binding to the apparently hundreds of nanometres in Figure 7a and it was mature PtNPCs in Figure 7b was unable to be calculated owing to the reticular morphology HEWL fibrils the metal ions are also affected by the fibrils’ immature The length of the mature PtNPCs in Figure 7b Counts C [PtCl6]2- nucleates along fibres and grows into chains after it is reduced Initially, immature Synthesis Self-assembled Noble Metal PtNPCs were mainlines, which absorb redundant platinumofnanoparticles when they continue to grow The AFE image in Figure 7c shows that the longest immature PtNPC was about µm The Ziming Xu, Lili Li, Hou Li and Faming Gao: Nanoparticle Chains Using Amyloid Fibrils of Lysozyme as Templates group space steric effect, which varies according to the fibril’s maturity Considering these aspects, we conducted the experiment of differentiation for synthesis of AuNPCs, PdNPCs, RhNPCs and PtNPCs above We believe that most of the metal NPCs with varying morphologies can be synthesized by using HEWL fibrils at different growing stages Conclusion In summary, we exhibited a simple route to yield gold nanoparticle chains (AuNPCs), palladium nanoparticle chains (PdNPCs), rhodium nanoparticle chains (RhNPCs) and platinum nanoparticle chains (PtNPCs) based on HEWL fibrils Through changing the experimental condi‐ tions, fibrosis time and temperature in the final stage, the AuNPCs with two types of morphologies were fabricated Their visible spectra and fluorescence were then discussed Abundant PdNPCs with length of several micrometres intertwisted with each other to form PdNPC networks Various morphologies of RhNPCs were also produced by adjusting the fibrosis time To determine the elements of RhNPCs, energy-dispersive X-ray spectroscopy (EDS) of the sample was carried out Finally, PtNPCs at different growing periods were presented It is well known that onedimensional AuNPCs, PdNPCs, RhNPCs and PtNPCs have many potential applications in the fields of catalysis, sensor, optical and so on Furthermore, by combining protein engineering with inorganic nanostructures synthe‐ sis, this development will benefit the design and assembly of more multifunctional bio-nanomaterials Acknowledgements This work was supported by the National Natural Science Foundation of China (Grants 21371149, 21101134) and Research Fund for the Doctoral Programme of Higher Education of China (Grant 20131333110010) and the Natural Science Foundation of Hebei (Grant 14961107D) References [1] Kundu S, Wang K, Huitink D, Liang H (2009) Photoinduced Formation of Electrically Conductive Thin Palladium Nanowires on DNA Scaffolds ACS Langmuir 25(17): 10146–1015 [2] Lee S Y, Lim J S, Harris M T (2012) Synthesis and Application of Virus-Based Hybrid Nanomaterials Wiley Periodicals Inc p 109 [3] Kumara M T, Tripp B C, Muralidharan S (2007) SelfAssembly of Metal Nanoparticles and Nanotubes on Bioengineered Flagella Scaffolds Chem Mater 19: 2056-2064 [4] Zhang L, Li N, Gao F, Hou L, Xu Z (2012) Insulin Amyloid Fibril: An Excellent Platform for Control‐ led Synthesis of Ultrathin Superlong Platinum Nanomater Nanotechnol, 2016, 6:4 | doi: 10.5772/62182 Nanowires with High Electrocatalytic Activity [J] J Am Chem Soc 134(28): 11326-11329 [5] He J, Xing Y F, Huang B, Zhang Y Z, Zeng C M (2009) Tea Catechins Induce the Conversion of Preformed Lysozyme Amyloid Fibrils to Amorphous Aggre‐ gates J Agric Food Chem 57: 11391–11396 [6] Bartolini M, Andrisano V (2010) Strategies for the Inhibition of Protein Aggregation in Human Diseases Chem Bio Chem 11: 1018-1035 [7] Sasahara K, Yagi H, Naiki H, Goto Y (2008) Amyloid Nucleation Triggered by Agitation of β2-Microglo‐ bulin under Acidic and Neutral pH Conditions Biochemistry 47: 2650-2660 [8] Sasahara K, Yagi H, Naiki H, Goto Y (2007) Heatinduced Conversion of β2-Microglobulin and Hen Egg-white Lysozyme into Amyloid Fibrils J Mol Biol 372: 981–991 [9] Kim J, Sasaki Y, Yoshida W, Kobayashi N, Veloso A J, Kerman K, Ikebukuro K, Sode K (2013) Rapid Cytotoxicity Screening Platform for Amyloid Inhibitors Using a Membrane-Potential Sensitive Fluorescent Probe Anal Chem 85: 185−192 [10] Humblet-Hua N P, Sagis L M C, Van Der Linden E (2008) Effects of Flow on Hen Egg White Lysozyme (HEWL) Fibril Formation: Length Distribution, Flexibility, and Kinetics J Agric Food Chem 56: 11875–11882 [11] Croguennec T, Nau F, Molle D, Le Graet Y, Brule G (2000) Iron and Citrate Interactions with Hen Egg White Lysozyme Food Chemistry 68: 29-35 [12] Dujardin E, Peet C, Stubbs G, Culver J N, Mann S (2003) Organization of Metallic Nanoparticles Using Tobacco Mosaic Virus Templates American Chemical Society Nano Letters 3: 413-417 [13] Sun Y, Xia Y (2004) Mechanistic Study on the Replacement Reaction between Silver Nanostruc‐ tures and Chloroauric Acid in Aqueous Medium J Am Chem Soc 126: 3892-3901 [14] Zhang L, Gao F (2012) Self-assembled Gold Nano‐ chains Hybrid Based on Insulin Fibrils J Nanopart Res 14: 855 [15] Yu Y Y, Chang S S, Lee C L, Wang C R C (1997) Gold Nanorods: Electrochemical Synthesis and Optical Properties J Phys Chem B 101: 6661-6663 [16] Creighton J A, Eadon D G (1991) Ultraviolet-visible Absorption Spectra of the Colloidal Metallic Elements J Chem Soc Faraday Trans 87: 3881-3891 [17] Jian Z, Liqing H, Yongchang W, Yimin L (2004) Fluorescence Spectrum Properties of Gold Nano‐ chains Physica E 25: 114-118 [18] Muhammed M A H, Ramesh S, Sinha S S, Pal S K, Pradeep T (2008) Two Distinct Fluorescent Quan‐ tum Clusters of Gold Starting from Metallic Nano‐ particles by pH-dependent Ligand Etching Nano Research 1: 333-340 [19] Zheng J, Zhang C, Dickson R M (2004) Highly Fluorescent, Water-soluble, Size-tunable Gold Quantum Dots Physical Review Letters 93: 077402 [20] Jiménez J L, Guijarro J I, Orlova E, Zurdo J, Dobson C M, Sunde M, Saibil H R (1999) Cryo-electron Microscopy Structure of an SH3 Amyloid Fibril and Model of the Molecular Packing The EMBO Journal 18: 815-821 Ziming Xu, Lili Li, Hou Li and Faming Gao: Synthesis of Self-assembled Noble Metal Nanoparticle Chains Using Amyloid Fibrils of Lysozyme as Templates ... morphology of the nanoparticles [17] As can be seen in Figure 3, the fluores‐ Ziming Xu, Lili Li, Hou Li and Faming Gao: Synthesis of Self- assembled Noble Metal Nanoparticle Chains Using Amyloid Fibrils. .. Structure of an SH3 Amyloid Fibril and Model of the Molecular Packing The EMBO Journal 18: 815-821 Ziming Xu, Lili Li, Hou Li and Faming Gao: Synthesis of Self- assembled Noble Metal Nanoparticle Chains. .. wire-like assembled structures of gold, like assembled structures of gold, palladium, rhodium and palladium, rhodium and platinum nanoparticles lysozyme- templated amyloid amy‐ fibrils The platinum nanoparticles