title: Attachment of micro- and nano-particles on tipless cantilevers for colloidal probe microscopy.
abstract: OBJECTIVE
  Current colloidal probe preparation techniques face several challenges in the production of functional probes using particles ⩽5 μm. Challenges include: glue encapsulated particles, glue altered particle properties, improper particle or agglomerate attachment, and lengthy procedures. We present a method to rapidly and reproducibly produce functional micro and nano-colloidal probes.
  
  
  METHODS
  Using a six-step procedure, cantilevers mounted on a custom designed 45° holder were used to approach and obtain a minimal amount of epoxy resin (viscosity of ∼14,000 cP) followed by a single micron/nano particle on the apex of a tipless cantilever. The epoxy and particles were prepared on individual glass slides and subsequently affixed to a 10× or 40× optical microscope lens using another custom designed holder. Scanning electron microscopy and comparative glue-colloidal probe measurements were used to confirm colloidal probe functionality.
  
  
  RESULTS
  The method presented allowed rapid and reproducible production of functional colloidal probes (80% success). Single nano-particles were prominently affixed to the apex of the cantilever, unaffected by the epoxy. Nano-colloidal probes were used to conduct topographical, instantaneous force, and adhesive force mapping measurements in dry and liquid media conveying their versatility and functionality in studying nano-colloidal systems.
authors.affiliation: The Faculty of Pharmacy, The University of Sydney, Pharmacy and Bank Building A15, Sydney, NSW 2006, Australia. Electronic address: dexter.dsa@sydney.edu.au.
authors.forename: Dexter J
authors.initials: DJ
authors.lastname: D'Sa
authors.affiliation: The Faculty of Pharmacy, The University of Sydney, Pharmacy and Bank Building A15, Sydney, NSW 2006, Australia.
authors.forename: Hak-Kim
authors.initials: HK
authors.lastname: Chan
authors.affiliation: The Faculty of Pharmacy, The University of Sydney, Pharmacy and Bank Building A15, Sydney, NSW 2006, Australia.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Chrzanowski
mesh_terms: D003102:Colloids; D008853:Microscopy / Q000379:methods*; D008863:Microspheres; D053758:Nanoparticles
chemical_list: D003102:Colloids
keywords: Atomic force microscope; Colloidal probe; Interfacial forces; Metered Dose Inhalers; Nano particle interactions; Suspension formulations