4 research outputs found
Anti-fouling TiO<sub>2</sub>‑Coated Polymeric Membrane Ion-Selective Electrodes with Photocatalytic Self-Cleaning Properties
Nowadays, using a polymeric membrane
ion-selective electrode (ISE)
to achieve reliable ion sensing in complex samples remains challenging
because of electrode fouling. To address this challenge, we describe
a polymeric membrane ISE with excellent anti-fouling and self-cleaning
properties based on surface covalent modification of an anatase TiO2 coating. Under ultraviolet illumination, the reactive oxygen
species produced by photocatalytic TiO2 can not only kill
microorganisms but also degrade organic foulants into carbon dioxide
and water, and a formed superhydrophilic film can effectively prevent
the adsorption of foulants, thus inhibiting the occurrence of biofouling
and organic fouling of the sensors. More importantly, residual foulants
could be fully self-cleaned through the flow of water droplets. By
using Ca2+-ISE as a model, an anti-fouling polymeric membrane
potentiometric sensor has been developed. Compared to the unmodified
electrode, the TiO2-coated Ca2+-ISE exhibits
remarkably improved anti-biofouling properties with a low bacterial
adhesion rate of 4.74% and a high inhibition rate of 96.62%. In addition,
the proposed electrode displays unique properties of anti-organic
dye fouling and a superior self-cleaning ability even after soaking
in a concentrated bacterial suspension of 109 CFU mL–1 for 60 days. The present approach can be extended
to improve the fouling resistance of other electrochemical or optical
membrane sensors and is promising for the construction of contamination-free
sensors
DataSheet1.DOCX
<p>Nowadays, it is still difficult for molecularly imprinted polymers (MIPs) to achieve homogeneous recognition since they cannot be easily dissolved in organic or aqueous phase. To address this issue, soluble molecularly imprinted nanorods have been synthesized by using soluble polyaniline doped with a functionalized organic protonic acid as the polymer matrix. By employing 1-naphthoic acid as a model, the proposed imprinted nanorods exhibit an excellent solubility and good homogeneous recognition ability. The imprinting factor for the soluble imprinted nanoroads is 6.8. The equilibrium dissociation constant and the apparent maximum number of the proposed imprinted nanorods are 248.5 ÎĽM and 22.1 ÎĽmol/g, respectively. We believe that such imprinted nanorods may provide an appealing substitute for natural receptors in homogeneous recognition related fields.</p
Soluble Molecularly Imprinted Polymer-Based Potentiometric Sensor for Determination of Bisphenol AF
Molecularly imprinted
polymer (MIP)-based polymeric membrane potentiometric
sensors have been successfully developed for determination of organic
compounds in their ionic and neutral forms. However, most of the MIP
receptors in potentiometric sensors developed so far are insoluble
and cannot be well dissolved in the polymeric membranes. The heterogeneous
molecular recognitions between the analytes and MIPs in the membranes
are inefficient due to the less available binding sites of the MIPs.
Herein we describe a novel polymeric membrane potentiometric sensor
using a soluble MIP (s-MIP) as a receptor. The s-MIP is synthesized
by the swelling of the traditional MIP at a high temperature. The
obtained MIP can be dissolved in the plasticized polymeric membrane
for homogeneous binding of the imprinted polymer to the target molecules.
By using neutral bisphenol AF as a model, the proposed method exhibits
an improved sensitivity compared to the conventional MIP-based sensor
with a lower detection limit of 60 nM. Moreover, the present sensor
exhibits an excellent selectivity over other phenols. We believe that
s-MIPs can provide an appealing substitute for the traditional insoluble
MIP receptors in the development of polymeric membrane-based electrochemical
and optical sensors
Trace-Level Potentiometric Detection in the Presence of a High Electrolyte Background
Polymeric membrane ion-selective electrodes (ISEs) have
become
attractive tools for trace-level environmental and biological measurements.
However, applications of such ISEs are often limited to measurements
with low levels of electrolyte background. This paper describes an
asymmetric membrane rotating ISE configuration for trace-level potentiometric
detection with a high-interfering background. The membrane electrode
is conditioned in a solution of interfering ions (e.g., Na<sup>+</sup>) so that no primary ions exist in the ISE membrane, thus avoiding
the ion-exchange effect induced by high levels of interfering ones
in the sample. When the electrode is in contact with the primary ions,
the interfering ions in the membrane surface can be partially displaced
by the primary ions due to the favorable ion–ligand interaction
with the ionophore in the membrane, thus causing a steady-state potential
response. By using the asymmetric membrane with an ion exchanger loaded
on the membrane surface, the diffusion of the primary ions from the
organic boundary layer into the bulk of the membrane can be effectively
blocked; on the other hand, rotation of the membrane electrode dramatically
reduces the diffusion layer thickness of the aqueous phase and significantly
promotes the mass transfer of the primary ions to the sample–membrane
interface. The induced accumulation of the primary ions in the membrane
boundary layer largely enhances the nonequilibrium potential response.
By using copper as a model, the new concept offers a subnanomolar
detection limit for potentiometric measurements of heavy metals with
a high electrolyte background of 0.5 M NaCl