title: Biofunctionalized nanoneedles for the direct and site-selective delivery of probes into living cells.
abstract: BACKGROUND
  Accessing the interior of live cells with minimal intrusiveness for visualizing, probing, and interrogating biological processes has been the ultimate goal of much of the biological experimental development.
  
  
  METHODS
  The recent development and use of the biofunctionalized nanoneedles for local and spatially controlled intracellular delivery brings in exciting new opportunities in accessing the interior of living cells. Here we review the technical aspect of this relatively new intracellular delivery method and the related demonstrations and studies and provide our perspectives on the potential wide applications of this new nanotechnology-based tool in the biological field, especially on its use for high-resolution studies of biological processes in living cells.
  
  
  CONCLUSIONS
  Different from the traditional micropipette-based needles for intracellular injection, a nanoneedle deploys a sub-100-nm-diameter solid nanowire as a needle to penetrate a cell membrane and to transfer and deliver the biological cargo conjugated onto its surface to the target regions inside a cell. Although the traditional micropipette-based needles can be more efficient in delivery biological cargoes, a nanoneedle-based delivery system offers an efficient introduction of biomolecules into living cells with high spatiotemporal resolution but minimal intrusion and damage. It offers a potential solution to quantitatively address biological processes at the nanoscale.
  
  
  CONCLUSIONS
  The nanoneedle-based cell delivery system provides new possibilities for efficient, specific, and precise introduction of biomolecules into living cells for high-resolution studies of biological processes, and it has potential application in addressing broad biological questions. This article is part of a Special Issue entitled Nanotechnologies - Emerging Applications in Biomedicine.
authors.affiliation: Department of Mechanical Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Kyungsuk
authors.initials: K
authors.lastname: Yum
authors.forename: Min-Feng
authors.initials: MF
authors.lastname: Yu
authors.forename: Ning
authors.initials: N
authors.lastname: Wang
authors.forename: Yang K
authors.initials: YK
authors.lastname: Xiang
mesh_terms: D000818:Animals; D002477:Cells / Q000737:chemistry*; D016503:Drug Delivery Systems; D006801:Humans; D015335:Molecular Probes / Q000737:chemistry / Q000378:metabolism*; D036103:Nanotechnology; D037742:Nanotubes, Carbon / Q000737:chemistry*
chemical_list: D015335:Molecular Probes; D037742:Nanotubes, Carbon