Polyethylene Terephthalate Membranes Research Articles

Enhancing 4-aminophenol detection using bismuth ferrite nanoparticles in functional nanochannels

This work presents a simple and rapid electrochemical method employing a conical nanochannel modified with bismuth ferrite (BFO) nanoparticles for the direct determination of 4-aminophenol (4-AP), a commonly used drug intermediate in pharmaceutical preparations. The phase pure BFO nanoparticles were synthesized by the coprecipitation technique. Subsequently, we created the single conical nanochannels within polyethylene terephthalate (PET) membranes using the asymmetric track-etching method. To facilitate the immobilization of BFO nanoparticles onto the nanochannel's surface, we initially functionalized it with poly (allylamine hydrochloride) (PAH). The BFO-modified single conical nanochannel obtained was utilized for sensing 4-AP, demonstrating significantly improved sensitivity within a linear dynamic response range from 400 μM to 1 mM, as compared to both unmodified and PAH-modified channels. To gain further insights into the interaction between BFO and 4-AP, we employed cyclic voltammetry and differential pulse voltammetry techniques. Our in-depth analysis, based on scan rate voltammograms, revealed that the interaction mechanism primarily involved the adsorption phenomenon between BFO nanoparticles and 4-AP. This enhancement in sensitivity, as corroborated by the electrochemical techniques, underscores the efficacy of the BFO-modified nanochannel for 4-AP detection. Robust conical nanochannels functionalized with nanoparticles, show promise in developing highly selective, cost-effective, and portable biosensors.

Chaotic dynamics of fractional viscoelastic PET membranes subjected to combined harmonic and variable axial loads

Nonlinear chaotic vibrations of fractional viscoelastic PET (polyethylene terephthalate) membranes subjected to combined harmonic and variable axial loads is investigated in this paper. Axial tension variations arise from the machine disturbances of the processing line of roll-to-roll manufacturing. The viscoelasticity of PET membrane is characterized by the fractional Kelvin-Voigt model. Based on the Hamilton principle, the equation of motion of the membrane is established with the consideration of geometric nonlinearity, and the Galerkin procedure is employed to discretize the resulting governing equation. For the solution, the finite difference method is utilized in conjunction with the Caputo-type fractional derivative to reliably estimate the nonlinear response of fractional viscoelastic PET membrane. The reliability of this numerical strategy is proved by the available results of the fractional system and comparison examples. The influence of system parameters on chaotic behaviors is described by the bifurcation diagram and the detailed responses at the set bifurcation parameters. The fractional model together with the analysis provides a fundamental framework for the control of viscoelastic substrates in flexible manufacturing.

Novel Chip for Applying Mechanical Forces on Human Skin Models Under Dynamic Culture Conditions.

In recent years the need for in vitro skin models as a replacement for animal studies has resulted in significant progress in the development of skin-on-a-chip models. These devices allow the fine control of the microenvironment of the model and the incorporation of chemical and physical stimuli. In this study, we describe the development of an easy and low-budget open-top dynamic microfluidic device for skin-on-a-chip experiments using polydimethylsiloxane and a porous polyethylene terephthalate membrane. The chip allows the incorporation of compressive stimuli during the cultivation period by the use of syringe pumps. Proof-of-concept results show the successful differentiation of the cells and establishment of the skin structure in the chip. The microfluidic skin-on-a-chip models presented in this study can serve as a platform for future drug and feasibility studies.

A wearable and capacitive sensor for leaf moisture status monitoring

The real-time and precise monitoring of plant physiological information, such as leaf capacitance, is important in agricultural production. However, current approaches for leaf capacitance monitoring are easy to cause damage to plants, which would decrease the accuracy of monitoring. In this study, we proposed the wearable electrodes for real-time monitoring of leaf capacitance. Gold nanoparticles were magnetron sputterred on polyethylene terephthalate (PET) membrane to form the wearable Au@PET electrodes. Due to their excellent flexibility, the electrodes showed good stability in both conductivity and capacitance sensing. The electrodes could be conformally attached to the leaf surface to form leaf capacitance sensor. It was found that capacitance value was positively correlated with leaf moisture content. Additionally, leaf capacitance showed higher value at night than daytime, with an extent of 12.02% and the results obtained from Au@PET electrodes were similar to the ones from traditional rigid electrodes. Besides, the growth and physiological parameters of Epipremnum aureum were not significantly affected during capacitance monitoring by Au@PET electrodes. Such results demonstrated the potential of wearable electrodes for real-time and precise monitoring of plant physiological information in the future.

Ultrafiltration membrane fabricated from polyethylene terephthalate plastic waste for treating microalgal wastewater and reusing for microalgal cultivation

Current study had made a significant progress in microalgal wastewater treatment through the implementation of an economically viable polyethylene terephthalate (PET) membrane derived from plastic bottle waste. The membrane exhibited an exceptional pure water flux of 156.5 ± 0.25 L/m2h and a wastewater flux of 15.37 ± 0.02 L/m2h. Moreover, the membrane demonstrated remarkable efficiency in selectively removing a wide range of residual parameters, achieving rejection rates up to 99%. The reutilization of treated wastewater to grow microalgae had resulted in a marginal decrease in microalgal density, from 10.01 ± 0.48 to 9.26 ± 0.66 g/g. However, this decline was overshadowed by a notable enhancement in lipid production with level rising from 181.35 ± 0.42 to 225.01 ± 0.11 mg/g. These findings signified the membrane's capacity to preserve nutrients availability within the wastewater; thus, positively influencing the lipid synthesis and accumulation within microalgal cells. Moreover, the membrane's comprehensive analysis of cross-sectional and surface topographies revealed the presence of macropores with a highly interconnected framework, significantly amplifying the available surface area for fluid flow. This exceptional structural attribute had substantially contributed to the membrane's efficacy by facilitating superior filtration and separation process. Additionally, the identified functional groups within the membrane aligned consistently with those commonly found in PET polymer, confirming the membrane's compatibility and efficacy in microalgal wastewater treatment.

Nonlinear dynamics of fractional viscoelastic PET membranes with linearly varying density

In this paper, the nonlinear dynamics of fractional viscoelastic polyethylene terephthalate (PET) membranes with linearly varying density are elaborated. The viscoelasticities of the PET membranes are characterized with the fractional Kelvin–Voigt model, and the density distribution is considered a linear fluctuation in the lateral direction. The geometrically nonlinear formulation is established with the von-Karman theory and the Hamilton principle. The Bubnov–Galerkin method is used to solve the resulting fractional differential equations, and a refined numerical scheme combining the finite difference with a discrete Caputo-type fractional derivative approximation is developed. Comparison examples are provided to substantiate the accuracy and effectiveness of the present method. A detailed parametric analysis is performed to illuminate the effects of the fractional order, density coefficient and various system parameters on the time response of the viscoelastic PET membranes. This study paves the way for fractional modelling and vibrational analysis of viscoelastic substrates in flexible electronics manufacturing.

A switchable ionic diode membrane enabled by sub-3 nm covalent organic framework channels

Various efforts have been made to mimic the regulatory properties of biological channels that exist in cell membranes of living organisms. Such ion channels are able to tune electric signals in response to changes in surrounding environments (e.g., pH or ions). Here, we report the design and fabrication of a novel pH-switchable ionic diode membrane (IDM), TFP-EB COF@PET, composed of a thin layer of sub-3 nm covalent organic framework (COF) channels and a polyethylene terephthalate (PET) membrane having conical nanochannels with tip size of 20–40 nm. The designed IDM is found to exhibit ion current rectification (ICR) over a wide range of electrolyte concentrations, attributable to its structural and charge asymmetries. Interestingly, the TFP-EB COF@PET can exhibit pH-switchable ion transport behaviors even though the surface charge natures of TFP-EB COF and PET channels remain unchanged. The mechanisms for the pH-switchable ICR properties are proposed to explain the inversion phenomenon. This work highlights the pH-switchable ionic transport properties of the sub-3 nm-scale COF-based IDM, as well as its potential for long-term operation under high salinity conditions.

Age-related decline in bone mineral transport and bone matrix proteins in osteoblasts from stromal stem cells.

We studied osteoblast bone mineral transport and matrix proteins as a function of age. In isolated bone marrow cells from long bones of young (3 or 4 mo) and old (18 or 19 mo) mice, age correlated with reduced mRNA of mineral transport proteins: alkaline phosphatase (ALP), ankylosis (ANK), the Cl-/H+ exchanger ClC3, and matrix proteins collagen 1 (Col1) and osteocalcin (BGLAP). Some proteins, including the neutral phosphate transporter2 (NPT2), were not reduced. These are predominately osteoblast proteins, but in mixed cell populations. Remarkably, in osteoblasts differentiated from preparations of stromal stem cells (SSCs) made from bone marrow cells in young and old mice, differentiated in vitro on perforated polyethylene terephthalate membranes, mRNA confirmed decreased expression with age for most transport-related and bone matrix proteins. Additional mRNAs in osteoblasts in vitro included ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), unchanged, and ENPP2, reduced with age. Decrease with age in ALP activity and protein by Western blot was also significant. Transport protein findings correlated with micro-computed tomography of lumbar vertebra, showing that trabecular bone of old mice is osteopenic relative to young mice, consistent with other studies. Pathway analysis of osteoblasts differentiated in vitro showed that cells from old animals had reduced Erk1/2 phosphorylation and decreased suppressor of mothers against decapentaplegic 2 (Smad2) mRNA, consistent with TGFβ pathway, and reduced β-catenin mRNA, consistent with WNT pathway regulation. Our results show that decline in bone density with age reflects selective changes, resulting effectively in a phenotype modification. Reduction of matrix and mineral transport protein expression with age is regulated by multiple signaling pathways.NEW & NOTEWORTHY This work for the first time showed that specific enzymes in bone mineral transport, and matrix synthesis proteins, in the epithelial-like bone-forming cell layer are downregulated with aging. Results were compared using cells extracted from long bones of young and old mice, or in essentially uniform osteoblasts differentiated from stromal stem cells in vitro. The age effect showed memory in the stromal stem cells, a remarkable finding.

Utilization of plastic bottle waste of polyethylene terephthalate as a low-cost membrane and its modifications for gas separation

Polyethylene terephthalate (PET) is a widely used polymer in packaging products, leading to the daily disposal of millions of PET bottles as waste. 1.1 to 8.8 million tonnes of plastic waste enter the sea each year. The environmental challenge of non-biodegradable PET waste can be addressed by utilizing it as a thin-layer membrane for gas separation. This study modified the PET membrane by blending it with Pebax polymer and adding zeolite as a filler to enhance its performance. Characterization techniques, including FTIR, SEM, TGA, tensile strength testing, and contact angle measurements, were performed on all modified membranes. The membranes were prepared using phase inversion via immersion precipitation. The results showed that the PET waste membrane had a denser surface pore morphology and asymmetrical cross-sectional pores than other membranes. Adding Pebax and zeolite resulted in a more regular sponge-like pore structure. The PET, PET-Pebax, and PET-Zeolite NaY-Pebax membranes exhibited hydrophilic properties, as indicated by contact angle values ranging from 48-78°. Regarding CO2/CH4 separation, the 9% PET-Pebax membrane had the highest CO2 permeability, a 21% increase from the original PET waste membrane. Adding zeolite to the 9% PET-Pebax membrane increased CO2 permeability to 1044%.

Novel proton-conducting materials based on a polyethylene terephthalate track-etched membrane modified with an N, P-containing ionic liquid

The development of novel membrane materials for hydrogen fuel cells, a promising environmentally friendly technology, represents a relevant research task. In this work, we propose an approach to creating proton-conducting membranes from an industrial polyethylene terephthalate (PET) dielectric track-etched film. An N, P-containing ionic liquid was used as a modifying agent, whose polymerization was carried out directly in the PET membrane pores. The ionic liquid was obtained using a novel approach to the directed synthesis of organophosphorus compounds from elemental phosphorus via the Trofimov-Gusarova reaction developed at the A.E. Favorsky Institute of Chemistry of the Siberian Branch of the Russian Academy of Sciences. The ionic liquid properties were characterized by NMR and IR spectroscopy. The application of the obtained N, P-containing ionic liquid onto a PET membrane was shown to yield a material exhibiting the required mechanical parameters for operation as proton-conducting membranes. The novel proton-conducting materials demonstrate a high proton conductivity of 77.76 mS·cm-1 at 353 K. The obtained proton-conducting membranes seem promising for application in hydrogen fuel cells, thus contributing to the development of effective alternative energy sources.

Rethinking of TEER measurement reporting for epithelial cells grown on permeable inserts

Transepithelial electrical resistance (TEER) measures electrical resistance across epithelial tissue barriers involving confluent layer(s) of cells. TEER values act as a prerequisite for determining the barrier integrity of cells, which play a key role in evaluating the transport of drugs, materials or chemicals of interest across an epithelial barrier. The measurements can be performed non-invasively by measuring ohmic resistance across a defined area. Thus, the TEER values are reported in Ω·cm2. In vitro epithelial models are typically assembled on semi-permeable inserts providing two-chamber compartments, and the majority of the studies use inserts with polyethylene terephthalate (PET) membranes. Recently, new inserts with different membrane types and properties have been introduced. However, the TEER values presented so far did not allow a direct comparison. This study presents the characterization of selected epithelial tissues, i.e., lung, retina, and intestine, grown on an ultra-thin ceramic microporous permeable insert (SiMPLI) and PET membranes with different properties, i.e., thickness, material, and pore numbers. We verified the epithelial cell growth on both inserts via phase-contrast and confocal laser scanning microscope imaging. Barrier characteristics were assessed by TEER measurements and also by evaluating the permeability of fluorescein isothiocyanate through cell layers. The findings indicated that background TEER value calculations and the available surface area for cell growth must be thoroughly assessed when new inserts are introduced, as the values cannot be directly compared without re-calculations. Finally, we proposed electrical circuit models highlighting the contributors to TEER recordings on PET and SiMPLI insert membranes. This study paves the way for making the ohmic-based evaluation of epithelial tissues’ permeability independent of the material and geometry of the insert membrane used for cell growth.

H2O2 and Phosphorylated Peptide Dual-Responsive Nanochannel Device.

Oxidation and protein phosphorylation are critical mechanisms involved in regulating various cellular activities. Increasing research has suggested that oxidative stress could affect the activities of specific kinases or phosphatases, leading to alterations in the phosphorylation status of certain proteins. Ultimately, these alterations can affect cellular signaling pathways and gene expression patterns. However, the relationship between oxidation and protein phosphorylation remains complex and not yet fully understood. Therefore, the development of effective sensors capable of detecting both oxidation and protein phosphorylation simultaneously presents an ongoing challenge. To address this need, we introduce a proof-of-concept nanochannel device that is dual-responsive to both H2O2 and phosphorylated peptide (PP). Specifically, we design a peptide GGGCEG(GPGGA)4CEGRRRR, which contains an H2O2-sensitive unit CEG, an elastic peptide fragment (GPGGA)4, and a phosphorylation site recognition fragment RRRR. When the peptides are immobilized on the inner walls of conical nanochannels in a polyethylene terephthalate membrane, this peptide-modified nanochannel device exhibits a sensitive response to both H2O2 and PPs. The peptide chains undergo a random coil-to-α-helix transition in response to H2O2, which leads to a close-to-open transition of the nanochannel, accompanied with a remarkable increase in the transmembrane ionic current. In contrast, binding of the peptides with PPs shields the positive charge of the RRRR fragments, causing a decrease of the transmembrane ionic current. These unique features enable the sensitive detection of reactive oxygen species released by 3T3-L1 cells stimulated by platelet-derived growth factor (PDGF) as well as PDGF-induced change in the PP level. Real-time kinase activity monitoring further confirms the device's potential utility for kinase inhibitor screening.

Three-Dimensional Cardiomyocyte-Nanobiosensing System for Specific Recognition of Drug Subgroups.

Abnormal cardiac electrophysiological activities significantly contribute to the incidence of cardiovascular diseases. Therefore, it is crucial to recognize effective drugs, which require an accurate, stable, and sensitive platform. Although conventional extracellular recordings offer a non-invasive and label-free manner to monitor the electrophysiological state of cardiomyocytes, the misrepresented and low-quality extracellular action potentials are difficult to provide accurate and high-content information for drug screening. This study presents the development of a three-dimensional cardiomyocyte-nanobiosensing system that can specifically recognize drug subgroups. The nanopillar-based electrode is manufactured by template synthesis and standard microfabrication technology on a porous polyethylene terephthalate membrane. Based on the cardiomyocyte-nanopillar interface, high-quality intracellular action potentials can be recorded by the minimally invasive electroporation. We validate the performance of a cardiomyocyte-nanopillar-based intracellular electrophysiological biosensing platform by two subclasses of sodium channel blockers, quinidine and lidocaine. The recorded intracellular action potentials accurately reveal the subtle differences between these drugs. Our study indicates that high-content intracellular recordings utilizing nanopillar-based biosensing can provide a promising platform for the electrophysiological and pharmacological investigation of cardiovascular diseases.

Performance of sponge and finger-like structures of PSF/PET membranes in hydrogen separation industry

Polysulfone (PSF) is one of the most popular commercial ultrafiltration membranes recently used in the field of high-performance gas separation. PSF membranes are distinguished by their sponge-like pore (SP) or finger-like pore (FP) structures. Also, they are usually reinforced with a porous backing layer, such as non-woven polyethylene terephthalate (PET) fabric, to improve their tensile strength. This research aims to study the effect of these different porous structures (SP and FP) and PET support layer on the gas permeation and selectivity characteristics of PSF membranes. The PSF/PET composite membranes were fabricated using a phase-inversion approach with different thicknesses of 100 µm and 200 µm to obtain SP and FP structures, respectively. The basic properties of the fabricated membranes, including morphology, coherence layers, pore structures, surface roughness, mechanical, chemical, and thermal were examined. Meanwhile, the pure gas measurements of H2, CH4, CO2, and N2 were taken using a laboratory setup at different pressures and temperatures up to 5 bar and 60 °C respectively. The scanning electron microscope results showed that the PSF solution had successfully penetrated between PET fibres closing their voids and formulated different thin and dense layers on their surfaces with SP and FP structures. Meanwhile, the PSF(FP)/PET membrane manifested bigger pore size (63 nm), lager porosity, higher strength, and higher thermal stability compared to PSF(SP)/PET membrane with estimated percentage of 24, 28, 23, 16 %, respectively. The gas measurements showed that the SP structure can provide higher gases permeability, as opposed to FP structure that showed better selectivity in the trend H2/CO2 (3.21) > H2/N2 (3.05) > H2/CH4 (1.99) with 36–80% improvement, when compared to PSF(SP)/PET membranes. Based on that, it is highly recommended to use PSF/PET with FP structure in hydrogen separation industry.

Wettability-Regulated Synthesis of Metal-Organic Framework Array with Subnanochannels Enables Efficient Separation of Mono-/Multivalent Metal Ions.

Achieving efficient separation of mono-/multivalent metal ions is essential in various fields, yet it remains a significant challenge. In this work, a metal-organic framework (MOF) array with subnanochannels that exhibit high selectivity and ion permeability in the sieving of mono-/multivalent metal ion was developed. Specifically, we used confined interfacial reaction at room temperature to synthesis the MOF array inside the micrometer through-pores of a polyethylene terephthalate (PET) membrane. The location of the oil/water interface was regulated by adjusting the surface wettability of the PET membrane. By taking advantage of size sieving effect of the subnanochannels of MOF crystals, we were able to effectively separate monovalent metal ions from multivalent metal ions with selectivity reaching up to 3930±373 (e.g., Li+ /Zr4+ ). The fluxes of Li+ ions were observed to be as high as 1.97 mol h-1 m-2 . The MOF array-based membrane with subnanochannels that we have developed exhibits great promise for applications in wastewater treatment, lithium extraction from salt-lake brines, and other related fields.

WS2 nanosheets rooted in polyethylene terephthalate membrane for gas barrier properties improvement

WS2 nanosheets rooted in polyethylene terephthalate membrane for gas barrier properties improvement

Waste to treasure: A superwetting fiber membrane from waste PET plastic for water-in-oil emulsion separation

Polyethylene terephthalate (PET) plastic membrane has attracted significant attention in chemical separation and pollution control due to its high mechanical properties and excellent chemical stability. However, designing inexpensive and efficient PET membrane materials for oil-water separation from waste PET plastics is still challenging but of great significance to environmental safety and resource protection. In this work, a superwetting PET fiber membrane with excellent structural stability and wetting selectivity was prepared from waste PET plastic, via electrostatic spinning, in-situ deposition and surface modification. The obtained superwetting PET fiber membrane exhibits the flourishing pore structure, wettability of superhydrophobic/super-oleophilic, and corrosion resistance (weak acid, strong base). Due to its stable porous structure and wettability properties, the membrane is capable of separating multi-type water-in-oil emulsion successfully, while with ideal separation flux (over 1100 L ·m−2·h−1), and separation efficiency (99.0–99.9%). Additionally, after the reusability tests with the least number of 40 cycles, the membrane shows favorable separation stability and excellent reusing performance, which possesses tremendous potential for efficient and continuous separation of water-in-oil emulsions. Therefore, the simple yet effective waste-to-resource strategy for waste PET plastic can not only reduce the environmental pollution caused by microplastics, but also develop an inexpensive and efficient membrane material for industrial emulsion separation.

Wound healing by transplantation of mesenchymal stromal cells loaded on polyethylene terephthalate scaffold: Implications for skin injury treatment

BackgroundSeveral clinical studies have shown that cellular therapy based on mesenchymal stromal cells (MSCs) transplantation may accelerate wound healing. One major challenge is the delivery system used for MSCs transplantation. In this work, we evaluated the capacity of a scaffold based on polyethylene terephthalate (PET) to maintain the viability and biological functions of MSCs, in vitro. We examined the capacity of MSCs loaded on PET (MSCs/PET) to induce wound healing in an experimental model of full-thickness wound. MethodsHuman MSCs were seeded and cultured on PET membranes at 37 °C for 48 h. Adhesion, viability, proliferation, migration, multipotential differentiation and chemokine production were evaluated in cultures of MSCs/PET. The possible therapeutic effect of MSCs/PET on the re-epithelialization of full thickness wounds was examined at day 3 post-wounding in C57BL/6 mice. Histological and immunohistochemical (IH) studies were performed to evaluate wound re-epithelialization and the presence of epithelial progenitor cells (EPC). As controls, wounds without treatment or treated with PET were established. ResultsWe observed MSCs adhered to PET membranes and maintained their viability, proliferation and migration. They preserved their multipotential capacity of differentiation and ability of chemokine production. MSCs/PET implants promoted an accelerated wound re-epithelialization, after three days post-wounding. It was associated with the presence of EPC Lgr6+ and K6+. DiscussionOur results show that MSCs/PET implants induce a rapid re-epithelialization of deep- and full-thickness wounds. MSCs/PET implants constitute a potential clinical therapy for treating cutaneous wounds.

Statistical analyses of pore radii on the performance of PET-nanocomposite membranes in the removal of iron and anions from Ibeshe River

The industrialization in Lagos State has impacted the Ibeshe watershed, as a result, lower water quality is being experienced. Hence, a novel way on the potential use of waste to treat Ibeshe watershed by synthesizing of graphene oxide and incorporating it into PET bottle waste membranes was studied. Polyethylene terephthalate (PET) membranes embedded with 1wt%, 2wt%, and 3wt% graphene oxide (GO) (M1, M2, and M3), were prepared via non-solvent-induced phase separation on polyester nonwoven support with the use of polyethylene glycol (PEG) as an additive. The surface morphologies of the three membranes appeared to be considerably different. The pore volume steadily reduces with an upsurge in the quantity of GO embedded in the membranes. A statistical assessment employing a uniform distribution curve was done using Python and the outcomes depict that the distribution of the radius data was firmly gathered around the mean. From the adsorption study, Fe2+ does not have the power to attract HCO3− in the transitory state at the surface of the membrane; hence HCO3− could not reach equilibrium at 80 min. The membranes’ performance was studied via flux and the rejection of iron and anions. The rejection rate calculated for the three anions and iron was observed to be high in the M3 membrane. The M3 membrane% rejection of the anions and iron is 96%, 85%%, 72%, and 60% for NO3−, Cl−, HCO3− and Fe, respectively. An upsurge in the amount of GO improved the water flux; hence, 3wt% GO gave the maximum water flux.

Ultra-low concentrations of detection for fluoride and trivalent chromium ions by multiple biomimetic nanochannels in a PET membrane

The development of a detection method for fluoride and chromium (III) ions using a PET membrane with multiple biomimetic nanochannels is descibed. An asymmetric chemical etching technique was used to create conical nanochannels with a PET (polyethylene terephthalate) nuclear track membrane. SEM images showed that the pore diameter of the tip and base sides of the nanochannel were ∼40 nm and ∼180 nm, respectively. The compounds (4-aminophenyl) boronic acid (APBA) and 5-amino-2-nitrobenzoic acid (ANBA), with a specific recognition for F− and Cr3+ respectively, were modified by a conventional method with EDC and NHS. The current-voltage (I–V) curves of the modified PET membranes in response to the target ions at different concentrations were measured with a picoammeter. Excellent linear relationships between the current value of the I–V curve at −2 V and the concentration of Cr3+ and F− were established to obtain standard detection curves for Cr3+ and F−. From these relationships unknown concentrations of Cr3+ and F− can be quantitatively detected, and the results showed that the detection limits of Cr3+ and F− were as low as 4.10 nM and 0.46 nM, respectively. The performance of the novel method was compared to conventional ICP-MS analysis by the determination of Cr3+ in tap water and samples of the Jing Mi diversion canal, and good agreement was found between the two methods. The accuracy and reliability of the method has demonstrated its potential applicability to a wide range of other ionic contaminants.