Journal
ANALYTICAL CHEMISTRY
Volume 94, Issue 5, Pages 2493-2501Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.analchem.1c04323
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Funding
- National Natural Science Foundation of China [22090050, 22090053, 21974126, 21874121, 51803194]
- Zhejiang Provincial Natural Science Foundation of China [LY19B030001]
- Engineering Research Center of Nano-Geomaterials of Ministry of Education [NGM2019KF013]
- Fundamental Research Funds for National Universities, China University of Geosciences (Wuhan)
- State Key Laboratory of Electro Anal. Chem [SKLEAC202003]
- National Key Research and Development Program of China [2018YFE0206900]
- National College Students' Innovation and Entrepreneurship Training Program of China [201910491002]
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The surface charge effects in nanoconfines play a crucial role in ion current rectification (ICR) of nanofluidics. By using polydopamine (PDA), the surface charge and hydrophobicity of the PEI gel network can be enhanced, leading to an increased ICR effect. The results demonstrate an adjustable and versatile strategy for manipulating ICR behaviors by adjusting local surface charge effects using PDA.
Surface charge effects in nanoconfines is one of the fundamentals in the ion current rectification (ICR) of nanofluidics, which provides entropic driving force by asymmetric surface charges and causes ion enrichment/depletion by the electrostatic interaction of fixed surface charges. However, the surface charge effect causes a significant electrostatic repulsion in nanoconfines, restricting additional like charge or elaborate chemistry on the highly charged confined surface, which limits ICR manipulation. Here, we use polydopamine (PDA), a nearly universal adhesive, that adheres to the highly positive-charged poly(ethyleneimine) (PEI) gel network in a nanochannel array. PDA enhances the ICR effect from a low rectification ratio of 9.5 to 92.6 by increasing the surface charge and hydrophobicity of the PEI gel network and, meanwhile, shrinking its gap spacing. Theoretical and experimental results demonstrate the determinants of the fixed surface charge in the enrichment/depletion region on ICR properties, which is adjustable by PDA-induced change in a nanoconfined environment. Chemically active PDA brings Au nanoparticles by chloroauric reduction for further hydrophobization and the modification of negative-charged DNA complexes in nanochannels, whereby ICR effects can be manipulated in versatile means. The results describe an adjustable and versatile strategy for adjusting the ICR behaviors of nanofluidics by manipulating local surface charge effects using PDA.
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