Polyaniline‐coated nanoelectrospray emitters treated with hydrophobic polymers at the tip

Abstract

In nanoelectrospray ionization (nanoESI) techniques, the hydrophilic character of the emitters generally produces large bases for the Taylor cones, thereby generating relatively large droplet sizes and consequently reduced sensitivity. In order to minimize this 'wetting' effect in nanoESI, a model hydrophobic polymer (an acrylic paint) was coated at the tip of commercial polyaniline (PANI)-coated emitters, and their performance was compared with that of unmodified PANI emitters using oxytocin and neuropeptide Y (NPY) solutions. In experiments with oxytocin, the hydrophobic emitter produced higher signal intensities (up to 3.6 times) as well as higher signal-to-noise ratios (33% increase) than those from the unmodified PANI emitter. In addition, the hydrophobic emitter showed reusability and a slightly wider linear dynamic range (10 nM to 50 microM, r2=0.9938) than that from the unmodified PANI emitter (10 nM to 10 microM, r2=0.9904). In the case of NPY, the hydrophobic emitter also enabled an approximately 350-fold overall increase in sensitivity than the unmodified PANI emitter (70 zmol vs. 25 amol). The enhanced performance of the hydrophobic emitter clearly indicates potential for further increases in nanoESI sensitivity using emitters with tailored hydrophobic overcoatings.

Review of recent advances in analytical techniques for the determination of neurotransmitters

“…Meanwhile, an improvement of nano-ESI emitter tips was developed to increase detection sensitivity toward OXT and other peptides like neuropeptide tyrosine (NPY) by hydrophobic polymer coating on the tip. [176] With further improvement of the LC-MS system, detecting of OXT and VP in vivo might be feasible in future.…”

Nanoelectrospray emitters: Trends and perspective

“…Tojo (2004) developed an etched emitter coated with a fluorinated polymer, commercialized by Omniseparo-TJ, Amagasaki, Japan, as FortisTip TM , which is claimed to provide stable electrospray for highly aqueous samples. In another example the commercially available NiagaraFlow emitters (Nanogenesys, Ithaca, NY, USA) were coated with a hydrophobic acrylic paint to provide better sensitivities (Choi & Wood, 2007).…”

Simulation‐based design of a microfabricated pneumatic electrospray nebulizer

“…Using such alternative arrangement the hydrophilic surface of the microdevice wets and suffers from droplet formation around the exit port . Using hydrophobic surface coating is one possibility to avoid wetting . Furthermore, the use of compressed gas flow was suggested to continuously remove the spread liquid, effectively preventing droplet formation.…”