Production and characterization of nanoparticles of defined shape and size

The focus of the research work in the Colloid Chemistry Group is on the formation and stabilization of nanoparticles of defined shape and size in different solvents and template phases using polyelectrolytes.

Gold nanoparticle formation in aqueous solution

Polycations [31, 37], polyanions [28] and polyampholytes [34] can be used as reducing and stabilizing agents in the production of gold nanoparticles of defined shape and size. The resulting gold nanoparticles are electrosterically stabilized and can be adjusted to particle sizes smaller than 4 nm by using sugar-modified polyethyleneimines (PEI) [44].

Gold nanoparticle formation in ionic liquids

In analogy to the aqueous system, gold nanoparticle formation can also be carried out in ionic liquids in the presence of PEI [45]. The resulting gold nanoparticles with an average particle size between 5 and 7 nm can be redispersed in chloroform and incorporated into electrodes via a covalent bond formation [45].

Nanoparticle formation in template phases


Water-in-oil microemulsion droplets can be used as a nanoreactor for particle formation. As already mentioned under point II, polyelectrolytes can be introduced into the water droplets without macroscopically phase separation. The polyelectrolyte-modified microemulsions can be used as a template phase directly for the nanoparticle formation [18,27,29,31,34-36,38-42]. The polyelectrolytes can be used as reducing agents in the formation of gold nanoparticles [31,34,38] or as stabilizing agents in CdS [30,40,42], BaSO4 [18,27,29,39,41], magnetite [35] and zinc sulfide production [36]. The polyelectrolytes are of particular importance in the redispersion of the nanoparticles after the complete removal of the solvents and prevent aggregation of the individual nanoparticles.

Vesicle phases

Gold nanoparticle formation can also take place directly on the surface of mixed phospholipid vesicles, in which triangles and rods are formed besides spherical gold particles [33]. In the presence of sugar-modified PEI, rods and triangles are formed, which is ascribed to the polycation [43]. The formation of nanoparticles directly in the bilayer phase, on the other hand, leads to an increased formation of rods [32]. The latest work (DFG project KO 1387 / 14-1) shows that in the presence of polyampholytes (PalPhBisCarb) the amount of nanotriangles can be optimized and their separation is successful [46].

TEM image of anisotropic gold nanoparticles prepared in the presence of PalPhBisCarb


Polyelectrolyte-modified nanoparticles can also be introduced into hydrogels or formed directly in the hydrogel [47].


  • Prof. M. Gradzielski (TU Berlin)
  • Dr. D. Appelhans (Leibniz Institut, Dresden)
  • Prof. S. Kudaibergenov (Kazakh National Technical University, Almaty)

Selected Publications:

[27] J. Koetz, J. Bahnemann, G. Lucas, B. Tiersch, S. Kosmella
Polyelectrolyte-modified microemulsions as new templates for the formation of nanoparticles
Colloids and Surfaces A: Physicochem. Eng. Aspects 250 (2004) 423-430 | DOI: 10.1016/j.colsurfa.2004.04.094
[28] C. Note, J. Koetz, S. Kosmella, B. Tiersch
Hydrophobically modified polyelectrolytes used as reducing and stabilizing agent for the formation of gold nanoparticles
Colloid & Polymer Science 283 (2005) 1334-1342 | DOI: 10.1007/s00396-005-1349-7
[29] J. Koetz, S. Andres, S. Kosmella, B. Tiersch
BaSO4 nanorods produced in polymer-modified bicontinuous microemulsions
Composite Interfaces 13 (2006) 4-6, 461-475 | DOI: 10.1163/156855406777408629
[30] J. Koetz, N. Jagielski, S. Kosmella, A. Friedrich, E. Kleinpeter
CdS nanocubes formed in phosphatidylcholin-based template phases
Colloids and Surfaces A: Physicochem. Eng. Aspects 288 (2006) 1-3, 36-43 | DOI: 10.1016/j.colsurfa.2006.01.013
[31] C. Note, S. Kosmella, J. Koetz
Poly(ethyleneimine) as Reducing and Stabilizing Agent for the Formation of Gold Nanoparticles in w/o Microemulsions
Colloids and Surfaces A: Physicochem. Eng. Aspects 290 (2006) 1-3, 150-156 | DOI: 10.1016/j.colsurfa.2006.05.018
[32] Q. Tong, S. Kosmella, J. Koetz
Formation of rod-like CdS nanoparticles in SDS/decanol based multilamellar vesicles
Progress in Colloid & Polymer Sci. (2006) 133:152-158 | DOI: 10.1007/3-540-32702-9_24
[33] D. Robertson, B. Tiersch, S. Kosmella, J. Koetz
Preparation of crystalline gold nanoparticles at the surface of mixed phosphatidylcholine-ionic surfactant vesicles
J. Colloid and Interface Sci. 305 (2007) 345-351 | DOI: 10.1016/j.jcis.2006.09.079
[34] C. Note, J. Koetz, L. Wattebled, A. Laschewsky
Effect of a new hydrophobically modified polyampholyte on the formation of inverse microemulsions and the preparation of gold nanoparticles
J. Colloid and Interface Sci. 308 (2007) 162-169 | DOI: 10.1016/j.jcis.2006.12.047
[35] J. Baier, J. Koetz, S. Kosmella, B. Tiersch, H. Rehage
Polyelectrolyte-modified microemulsions and their use as templates for the formation of magnetite nanoparticles
J. Phys. Chem. B 111 (2007) 8612-8618 | DOI: 10.1021/jp068995g
[36] J. Koetz, J. Baier, S. Kosmella
Formation of zinc sulfide and hydroxylapatite nanoparticles in polyelectrolyte-modified microemulsions
Colloid & Polymer Sci. 285 (2007) 1719-1726 | DOI: 10.1007/s00396-007-1757-y
[37] A. Köth, J. Koetz, D. Appelhans, B. Voit
„Sweet“ Gold Nanoparicles with Oligosaccharide-modified Poly(ethyleneimine)
Colloid & Polymer Sci. 286 (2008) 1317-1327 | DOI: 10.1007/s00396-008-1903-1
[38] S. Lutter, J. Koetz, B. Tiersch, A. Boschetti-de-Fierro, V. Abetz
Formation of gold nanoparticles in triblock terpolymer-modified inverse microemulsions
Colloids and Surfaces A: Physicochem. Eng. Aspects 329 (2008) 169-176 | DOI: 10.1016/j.colsurfa.2008.07.014
[39] J. Koetz, S. Lutter, M. Fechner
Polymer-modified microemulsions as templates for the formation of BaSO4 nanoparticles
Tenside Surf. Det. 45 (2008) 6, 326-329 | DOI: 10.3139/113.100391
[40] S. Lutter, J. Koetz, B. Tiersch, S. Kosmella
Formation of cadmium sulfide nanoparticles in poly(ethylene glycol)- modified microemulsions
Progress in Colloid & Polymer Sci. 134 (2008) 149-155 | DOI: 10.1007/2882_2008_082
[41] S. Lutter, J. Koetz, B. Tiersch, S. Kosmella
Polymer-modified bicontinuous microemulsions used as a template for the formation of nanorods
J. Dispersion Sci. and Technology 30 (2009) 745-752 | DOI: 10.1080/01932690802643113
[42] J. Koetz, K. Gawlitza, S. Kosmella
Formation of organically and inorganically passivated CdS nanoparticles in reverse microemulsions
Colloid & Polymer Sci. 288 (2010) 257-263 | DOI: 10.1007/s00396-009-2154-5
[43] A. Köth, D. Appelhans, D. Robertson, B. Tiersch, J. Koetz
Use of Weakly Cationic Dendritic Glycopolymer for Morphological Transformation of Phospholipid Vesicles into Tube-like Network
Soft Matter (2011) 7, 10581-10584 | DOI: 10.1039/C1SM06439H
[44] A. Köth, B. Tiersch, D. Appelhans, M. Gradzielski, H. Cölfen, J. Koetz
Synthesis of core-shell gold nanoparticles with maltose-modified poly(ethyleneimine)
J. Dispersion Sci. and Technology (2012) 33, 52-60 | DOI: 10.1080/01932691.2010.530084
[45] S. Frasca, O. Rojas, J. Salewski, B. Neumann, K. Stiba, I.M. Weidinger, B. Tiersch, S. Leimkühler, J. Koetz, U. Wollenberger
Human sulfite oxidase electrochemistry on gold nanoparticles modified electrode
Bioelectrochemistry 87 (2012), 33-41 | DOI: 10.1016/j.bioelechem.2011.11.012
[46] F. Liebig, R. M. Sarhan, C. Prietzel, A. Reinecke, J. Koetz:
“Green” gold nanotriangles: synthesis, purification by polyelectrolyte/micelle depletion flocculation and performance in surface-enhanced Raman scattering,
RSC Advances 6 (2016) 33561-33568 | DOI: 10.1039/C6RA04808K
[47] S. Kudaibergenov, Zh. Ibraeva, N. A. Dolya, B. Musabayeva, A. Zharmagambetova, J. Koetz
Semi-Interpenetrating hydrogels of polyelectrolytes, polymer-metal complexes and polymer-protected palladium nanoparticles
Macromol. Symposia 274 (2008) 11-21 | DOI: 10.1002/masy.200851403