Single Nanoparticle Translocation Through Chemically Modified Solid Nanopore

Abstract

The nanopore sensor as a high-throughput and low-cost technology can detect single nanoparticle in solution. In the present study, the silicon nitride nanopores were fabricated by focused Ga ion beam (FIB), and the surface was functionalized with 3-aminopropyltriethoxysilane to change its surface charge density. The positively charged nanopore surface attracted negatively charged nanoparticles when they were in the vicinity of the nanopore. And, nanoparticle translocation speed was slowed down to obtain a clear and deterministic signal. Compared with previous studied small nanoparticles, the electrophoretic translocation of negatively charged polystyrene (PS) nanoparticles (diameter ~100 nm) was investigated in solution using the Coulter counter principle in which the time-dependent nanopore current was recorded as the nanoparticles were driven across the nanopore. A linear dependence was found between current drop and biased voltage. An exponentially decaying function (td ~ e−v/v0) was found between the duration time and biased voltage. The interaction between the amine-functionalized nanopore wall and PS microspheres was discussed while translating PS microspheres. We explored also translocations of PS microspheres through amine-functionalized solid-state nanopores by varying the solution pH (5.4, 7.0, and 10.0) with 0.02 M potassium chloride (KCl). Surface functionalization showed to provide a useful step to fine-tune the surface property, which can selectively transport molecules or particles. This approach is likely to be applied to gene sequencing.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-016-1255-6) contains supplementary material, which is available to authorized users.

Surface coatings for solid-state nanopores

“…283 In the context of nanopores, silanization allows for the functionalization of pore walls by enabling the attachment of DNA, 173,175,178,183 dendrimers, 174 nucleoporins, 176 aldehydes, 172,177 spiropyran moieties, 181 cysteines, 187 carboxylic acid, 172 EDTA, 188 peptides, 189,191 and polymer brushes 182 to chemical groups that are attached to the silane molecule. Apart from the possibility of such attachments, silanization can generate a coating with antifouling properties 184 and can be used to manipulate ICR 185 and other charge-based properties, 179 including the modulation of surface charge by changing the pH value of the recording electrolyte 129,180,186 Fig . 6 The functionalization of a quartz nanopipette by the physisorption of PLL and subsequent immobilization of IgG molecules.…”

“…171 Tan et al performed silanization with 3-aminopropyltriethoxysilane (APTES) on silicon nitride nanopores (which typically have a thin layer of SiO 2 on their surface 287 ) to render the net charge of the pore surface positive due to protonated terminal amine groups. 179 The authors chose a functionalization with amine groups to reduce EOF-related drag as well as to attract negatively charged nanoparticles to the pore entrance for detection of translocation events at increased frequency. 179 Wanunu and Meller created nanopores that responded to changes in pH or to the presence of certain proteins by attaching carboxylic acid or aldehyde groups to silane coatings on the pore.…”

“…179 The authors chose a functionalization with amine groups to reduce EOF-related drag as well as to attract negatively charged nanoparticles to the pore entrance for detection of translocation events at increased frequency. 179 Wanunu and Meller created nanopores that responded to changes in pH or to the presence of certain proteins by attaching carboxylic acid or aldehyde groups to silane coatings on the pore. To this end, they coated the pores with a variety of organosilane reagents containing epoxy, methoxyethylene glycol and amine moieties before attaching molecules that either displayed carboxylic acid groups or displayed aldehyde groups upon conjugation.…”

Application of Solid-State Nanopore in Protein Detection

“…For preventing non-specific interactions or advancing functionality, solid-state nanopores can be modified or coated with various materials. Typical organic materials include polyethylene glycol (PEG) [31], fluid lipid coatings [32], and 3-aminopropyltriethoxysilane (APTES) for salinization [33,34]. Inorganic materials such as Al 2 O 3 [35], SiO 2 [36], and HfO 2 [37] can be deposited by atomic layer deposition (ALD) and chemical vapor deposition (CVD), for better signal-to-noise ratio.…”

Fabrication of polydimethylsiloxane (PDMS) nanofluidic chips with controllable channel size and spacing

“…Nanochannel devices with structure size smaller than 100 nm are critical in experimental studies and applications of nanofluidics. Such a small size gives rise to many new transport phenomena in nanoscale due to the overlap of electric double layers (EDL) [1][2][3][4] and leads to possibilities of detection, manipulation and controlling of individual nanoscale targets, such as virus [5][6][7] , bacteria 8,9 , DNAs [10][11][12][13][14][15] , proteins 16,17 and nanoparticles 14,[18][19][20] . Therefore, relatively simple and reliable methods of fabricating small nanochannels are essential to these studies and applications.…”