Chien-Ching Wu

Publications (5)38.61 Total impact

• Article: Strategies for patterning biomolecules with dip-pen nanolithography.

  Chien-Ching Wu, David N Reinhoudt, Cees Otto, Vinod Subramaniam, Aldrik H Velders
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  ABSTRACT: Dip-pen nanolithography (DPN) is an atomic force microscopy (AFM)-based lithography technique, which has the ability to fabricate patterns with a feature size down to approximately 15 nm using both top-down and bottom-up approaches. DPN utilizes the water meniscus formed between an AFM tip and a substrate to transfer ink molecules onto surfaces. A major application of this technique is the fabrication of micro- and nano-arrays of patterned biomolecules. To achieve this goal, a variety of chemical approaches has been used. This review concisely describes the development of DPN in the past decade and presents the related chemical strategies that have been reported to fabricate biomolecular patterns with DPN at micrometer and nanometer scale, classified into direct- and indirect DPN methodologies, discussing tip-functionalization strategies as well.
  Small 03/2011; 7(8):989-1002. · 8.35 Impact Factor
• Article: Pyrylium monolayers as amino-reactive platform.

  Francesca A Scaramuzzo, Arántzazu González-Campo, Chien-Ching Wu, Aldrik H Velders, Vinod Subramaniam, Giancarlo Doddi, Paolo Mencarelli, Mario Barteri, Pascal Jonkheijm, Jurriaan Huskens
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  ABSTRACT: A new monolayer platform based on pyrylium has been developed which is reactive towards amine-terminated (bio)molecules. Upon reaction, a switch in fluorescence properties of the monolayer signifies successful immobilization of these molecules.
  Chemical Communications 06/2010; 46(23):4193-5. · 6.17 Impact Factor
• Article: Protein immobilization on Ni(II) ion patterns prepared by microcontact printing and dip-pen nanolithography.

  Chien-Ching Wu, David N Reinhoudt, Cees Otto, Aldrik H Velders, Vinod Subramaniam
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  ABSTRACT: An indirect method of protein patterning by using Ni(II) ion templates for immobilization via a specific metal-protein interaction is described. A nitrilotriacetic acid (NTA)-terminated self-assembled monolayer (SAM) allows oriented binding of histidine-tagged proteins via complexation with late first-row transition metal ions, such as Ni(II). Patterns of nickel(II) ions were prepared on NTA SAM-functionalized glass slides by microcontact printing (microCP) and dip-pen nanolithography (DPN) to obtain micrometer and submicrometer scale patterns. Consecutive dipping of the slides in 6His-protein solutions resulted in the formation of protein patterns, as was subsequently proven by AFM and confocal fluorescence microscopy. This indirect method prevents denaturation of fragile biomolecules caused by direct printing or writing of proteins. Moreover, it yields well-defined patterned monolayers of proteins and, in principle, is indifferent for biomolecules with a high molecular weight. This approach also enabled us to characterize the transfer of Ni(II) ions on fundamental parameters of DPN, such as writing speeds and tip-surface contact times, while writing with the smallest possible ink "molecules" (i.e., metal ions).
  ACS Nano 02/2010; 4(2):1083-91. · 10.77 Impact Factor
• Article: Porous multilayer-coated AFM tips for dip-pen nanolithography of proteins.

  Chien-Ching Wu, Huaping Xu, Cees Otto, David N Reinhoudt, Rob G H Lammertink, Jurriaan Huskens, Vinod Subramaniam, Aldrik H Velders
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  ABSTRACT: A simple and novel method for fabricating nanoporous-structure-coated silicon nitride tips for dip-pen nanolithography (DPN) by using the layer-by-layer (LbL) technique has been developed. The pore sizes can be adjusted by treating the LbL films coated onto the amino-terminated self-assembled monolayer (NH(2)-SAM)-functionalized AFM tip surface with a base solution for different periods of time. This hydrophilic porous material can absorb biomolecules easily and also provides a larger-volume ink reservoir compared with a bare silicon nitride tip. Proof-of-concept of the porous AFM tip is demonstrated by using fluorescent proteins as ink molecules to fabricate protein patterns at the micrometer and submicrometer length scales.
  Journal of the American Chemical Society 06/2009; 131(22):7526-7. · 9.91 Impact Factor
• Article: Fabrication and visualization of metal-ion patterns on glass by dip-pen nanolithography.

  Lourdes Basabe-Desmonts, Chien-Ching Wu, Kees O van der Werf, Maria Peter, Martin Bennink, Cees Otto, Aldrik H Velders, David N Reinhoudt, Vinod Subramaniam, Mercedes Crego-Calama
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  ABSTRACT: Fluorescent self-assembled monolayers (SAMs) are used as dip-pen nanolithography (DPN) substrates for the fabrication of patterns of Ca(2+) and Cu(2+) ions. The driving force for the transfer of these ions from an atomic force microscopy (AFM) tip to the surface is their complexation to organic ligands on the monolayer. By means of fluorescent surfaces, the patterns can be visualized under a fluorescence microscope. We use a custom-built atomic force fluorescence microscope (AFFM), a combination of atomic force and confocal fluorescence microscopes, to deposit the metal ions onto the sensing SAMs by DPN and to subsequently visualize modulations of fluorescence intensity in a sequential write-read mode.
  ChemPhysChem 08/2008; 9(12):1680-7. · 3.41 Impact Factor