Highly sensitive photoelectrochemical sensing of bisphenol A based on zinc phthalocyanine/TiO2 nanorod arrays

Antibacterial and surface properties of post-light-activated metal-free phthalocyanine-deposited TiO2 nanotube smart surfaces

The utilisation of implantable medical devices has become safer and more prevalent since the establishment of sterilisation methods and techniques a century ago. Nevertheless, device-associated infections remain a significant and growing concern, particularly in light of the continued rise in the number of medical device implantations. This underscores the imperative for the development of efficacious prevention and treatment strategies for device-associated infections, as well as further investigation into the design of innovative antibacterial surfaces for medical device applications. The motivation of this work is to investigate the post-light-activated antibacterial photosensitive surfaces fabricated on medical titanium (Ti) surfaces. Thus, in this work, metal-free phthalocyanine (H2Pc)-deposited TiO2 nanotube (TNT) array smart photosensitive surfaces were fabricated on titanium (Ti) surfaces for medical device applications. First, well-ordered nanotube surfaces were produced on titanium using an anodic oxidation (AO) process. Then, H2Pc was accumulated onto TNT surfaces using a physical vapour deposition (PVD-TE) process. H2Pc-deposited TNT surfaces were fabricated on Ti substrates by combining AO and physical vapour deposition (PVD-TE) processes in this work for the first time in the literature. H2Pc was largely coated onto TNT arrays and exhibited elemental homogeneity throughout the whole surface. The contact angle of H2Pc-deposited TNT surfaces was about 89° whereas other Ti and TNT surfaces demonstrated hydrophilic characteristics. Therefore, they exhibited remarkable hydrophobic behavior in terms of antibacterial properties. Importantly, compared to Ti and TNT surfaces, the bacterial inhibition on sunlight-activated H2Pc-deposited TNT surfaces was 94.9% for S. aureus and 97.3% for E. coli, respectively. According to these results, H2Pc-deposited TNT innovative surfaces provided superior antibacterial activity post-light-activation under sunlight due to their photosensitive character.

Self-Assembled Perylene Diimide (PDI) Nanowire Sensitized In2O3@MgIn2S4 S-Scheme Heterojunction as Photoelectrochemical Biosensing Platform for the Detection of CA15-3

Inorganic/organic heterojunctions show promising applications as high-performance sensing platforms for photoelectrochemical (PEC) immunosensors. This work reports constructing a PEC biosensor for CA15-3 based on a self-assembled perylene diimide (PDI) nanowire sensitized In2O3@MgIn2S4 S-scheme heterojunction platform. P-type semiconductor Cu2O nanoparticles were designed as a signal burst source and were used as immunoassay labels. The carboxyl group on self-assembled PDI nanowires eliminates the step of additional surface functionalization for covalent immobilization of the capture elements. The π-π stacking of PDI enhances electron generation efficiency, while the carboxylic acid groups on PDI promote electron transfer. The performance of the constructed sensor was validated using CA15-3 as a model. The experimental results showed that the sensor based on In2O3@MgIn2S4/PDI has excellent selectivity, stability, and reproducibility, and can sensitively detect CA15-3 in the range of 0.001-100 U·mL-1 with the detection limit of 0.00056 U·mL-1. The sensor has a broad application prospect. It is hoped that this research work based on the unique advantages of the organic compound PDI will inspire other researchers to design light-responsive materials and promote the development of the field of photoelectrochemical sensing.

Organic photoelectrochemical transistor aptasensor for dual-mode detection of DEHP with CRISPR-Cas13a assisted signal amplification

Emerging organic photoelectrochemical transistors (OPECTs) with inherent amplification capabilities, good biocompatibility and even self-powered operation have emerged as a promising detection tool, however, they are still not widely studied for pollutant detection. In this paper, a novel OPECT dual-mode aptasensor was constructed for the ultrasensitive detection of di(2-ethylhexyl) phthalate (DEHP). MXene/In2S3/In2O3 Z-scheme heterojunction was used as a light fuel for ion modulation in sensitive gated OPECT biosensing. A transistor system based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) converted biological events associated with photosensitive gate achieving nearly a thousand-fold higher current gain at zero bias voltage. This work quantified the target DEHP by aptamer-specific induction of CRISPR-Cas13a trans-cutting activity with target-dependent rolling circle amplification as the signal amplification unit, and incorporated the signal changes strategy of biocatalytic precipitation and TMB color development. Combining OPECT with the auxiliary validation of colorimetry (CM), high sensitivity and accurate detection of DEHP were achieved with a linear range of 0.1 pM to 200 pM and a minimum detection limit of 0.02 pM. This study not only provides a new method for the detection of DEHP, but also offers a promising prospect for the gating and application of the unique OPECT.

Recent advances in the use of composite titanium dioxide nanomaterials in the food industry

Titanium dioxide (TiO2 ) nanomaterials have attracted significant attention due to their good biocompatibility and potential for multifunctional applications. In the last few years, there has been growing interest in the use of TiO2 nanomaterials in the food industry. However, a systematic review of the synthesis methods, properties, and applications of TiO2 nanomaterials in the food industry is lacking. In this review, we provide a summary of the synthesis and properties of TiO2 nanomaterials and their composites, with a focus on their applications in the food industry. We also discuss the potential benefits and risks of using TiO2 nanomaterials in food applications. This review aims to promote food innovation and improve food quality and safety.

MXene-Enhanced Bi2S3/CdIn2S4 Heterojunction Photosensitive Gate for DEHP Detection in a Signal-On OPECT Aptamer Biosensor

Organic electrochemical transistors with signal amplification and good stability are expected to play a more important role in the detection of environmental pollutants. However, the bias voltage at the gate may have an effect on the activity of vulnerable biomolecules. In this work, a novel organic photoelectrochemical transistor (OPECT) aptamer biosensor was developed for di(2-ethylhexyl) phthalate (DEHP) detection by combining photoelectrochemical analysis with an organic electrochemical transistor, where MXene/Bi2S3/CdIn2S4 was employed as a photoactive material, target-dependent DNA hybridization chain reaction was used as a signal amplification unit, and Ru(NH3)63+ was selected as a signal enhancement molecule. The poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-based OPECT biosensor modulated by the MXene/Bi2S3/CdIn2S4 photosensitive material achieved a high current gain of nearly a thousand times at zero bias voltage. The developed signal-on OPECT sensing platform realized sensitive and specific detection of DEHP, with a detection range of 1-200 pM and a minimum detection limit of 0.24 pM under optimized experimental conditions, and its application to real water samples was also evaluated with satisfactory results. Hence, the construction of this OPECT biosensing platform not only provides a promising tool for the detection of DEHP but also reveals the great potential of the OPECT application for the detection of other environmental toxins.

MOF-derived CeO2/Co3O4-Fe2O3@CC nanocomposites as highly sensitive electrochemical sensor for bisphenol a detection

A novel CeO₂/Co₃O₄-Fe₂O₃@CC electrode derived from CeCo-MOFs was developed for detecting the endocrine disruptor bisphenol A (BPA). Firstly, bimetallic CeCo-MOFs were prepared by hydrothermal method, and obtained material was calcined to form metal oxides after doping Fe element. The results suggested that hydrophilic carbon cloth (CC) modified with CeO₂/Co₃O₄-Fe₂O₃ had good conductivity and high electrocatalytic activity. By the analyses of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), the introduction of Fe increased the current response and conductivity of the sensor, greatly increasing the effective active area of the electrode. Significantly, electrochemical test proves that the prepared CeO₂/Co₃O₄-Fe₂O₃@CC had excellent electrochemical response to BPA with a low detection limit of 8.7 nM, an excellent sensitivity of 20.489 μA/μM·cm², a linear range of 0.5-30 μM, and strong selectivity. In addition, the CeO₂/Co₃O₄-Fe₂O₃@CC sensor had a high recovery rate for the detection of BPA in real tap water, lake water, soil eluent, seawater, and PET bottle samples, which showed its potential in practical applications. To sum up, the CeO₂/Co₃O₄-Fe₂O₃@CC sensor prepared in this work had excellent sensing performance, good stability and selectivity for BPA, which can be well used for the detection of BPA.

Au/TiO2-based molecularly imprinted photoelectrochemical sensor for dibutyl phthalate detection

A photoelectrochemical molecular imprinting sensor based on Au/TiO₂ nanocomposite was constructed for the detection of dibutyl phthalate. Firstly, TiO₂ nanorods were grown on fluorine-doped tin oxide substrate by hydrothermal method. Then, gold nanoparticles were electrodeposited on TiO₂ to fabricate Au/TiO₂. Finally, molecular imprinted polymer was electropolymerized on the Au/TiO₂ surface to construct MIP/Au/TiO₂ PEC sensor for DBP. The conjugation effect of MIP accelerates the electron transfer between TiO₂ and MIP, which can greatly improve the photoelectric conversion efficiency and sensitivity of the sensor. In addition, MIP can also provide sites for highly selective recognition of dibutyl phthalate molecules. Under optimal experimental conditions, the prepared photoelectrochemical sensor was used for the quantitative determination of DBP and the results showed a wide linear range (50 to 500 nM), a low limit of detection (0.698 nM), and good selectivity. The sensor was used in a study of real water samples to show that it has promising applications in environmental analysis.

A membrane/mediator-free high-power density dual-photoelectrode PFC aptasensor for lincomycin detection in milk and chicken

Over use of lincomycin (LIN) as antibiotic in animals can lead to multiple harmful impacts to public health, thus detection of LIN at trace level in milk and chicken sample matrixes is vital. In this work, Zinc phthalocyanine nanoparticles sensitized MoS₂ (ZnPc/MoS₂) was firstly developed as a novel photocathode material combined with nitrogen-doped graphene-loaded TiO₂ nanoparticles (TiO₂/NG) as photoanode material to construct a dual-photoelectrode photofuel cell (PFC). The as-prepared membrane/mediator-free PFC achieved excellent output performance that the maximum power density (P_max) reached 11.83 μW cm^-2. Specific aptamers are adopted as LIN recognition elements, the as-proposed self-powered aptasensor for LIN exhibited a linear scope in 10^-11 -10^-5 mol L^-1 along with a low detection limit (3S/N) of 3.33 pmol L^-1. Consequently, such high-power density dual-photoelectrode PFC aptasensor may be a reassuring candidate electrochemical sensor for the detection of trace contamination in food samples.

Nickel hexacyanoferrate nanoparticle-decorated 3D rGO composites-based electrochemical sensing platform for detection of di-2-ethylhexyl phthalate

A label-free and efficient electrochemical (EC) sensing platform for di-2-ethylhexyl phthalate (DEHP) was developed based on in situ probe nickel hexacyanoferrate nanoparticle (NiHCF NP)-decorated three-dimensional reduced graphene oxide (3D rGO) composites. NiHCF NPs in the composites as an in situ probe show a pair of well-defined peaks with good reversibility and stability. Coupling 3D rGO with NiHCF NPs not only improved the electron transfer capability of NiHCF NPs but also provided more sites for aptamer immobilization. The synthesized NiHCF NP-decorated 3D rGO composites were used to act as a substrate for the immobilization of anti-DEHP aptamer by the covalent bonding method. The designed EC sensing platform displays excellent sensing performance for DEHP with a low detection limit of 3.64 pg/L, and a linear working range of 0.01 - 1000 ng/L. The application of the sensing platform to actual environmental samples was studied and satisfactory results were obtained. Thus, the proposed EC sensing platform would provide a potential tool for efficient detection of pollutants in the environment.

Capsulation of red emission chromophore into the CoZn ZIF as nanozymes for on-site visual cascade detection of phosphate ions, o-phenylenediamine, and benzaldehyde

Accurate on-site profiling of the pollutants is of vital significance for estimating environmental pollution. Herein, we propose a paper-based fluorescence-sensing system to precisely report the level of multiple pollutants. A high-performance fluorescence-sensor for apparatus-free and visual on-site tandem precisely reporting phosphate ions (Pi), o-phenylenediamine (OPD), and benzaldehyde (BA) levels have been fabricated successfully by introducing synthesized red emission (>600 nm) fluorescent chromophore 10-(diethylamino)-3-hydroxy-5,6-dihydrobenzo [c]xanthen-12-ium (HTD) into the environment of CoZn zeolitic imidazolate framework (CoZn ZIF) by a simple stirring method. CoZn ZIF@HTD with the bimetallic nodes not merely provided main Zn²⁺ sites for specific recognition of Pi to generate an enhanced red fluorescent optical signal, Co³⁺/Co²⁺ exhibited excellent peroxidase-like activity for the catalytic oxidation of OPD substrate in the presence of H₂O₂ resulting in color changing from red to yellow. Subsequently, the obvious yellow fading of the OPDox species took place with the addition of BA. By virtue of the sensitively visual tandem detection of Pi, OPD, and BA, the sensor can be applied to real wastewater samples. Meanwhile, this fluorescent sensor was further adopted for practical application in confocal cell imaging and security inks. Overall, this work established a fluorescent sensing system with integrated multifunctional applications for environmental and biological samples, implying the great potential for simultaneous real-time cascade detection of various important pollutants with the merit of low-cost, time-saving, and easy-to-use.

BODIPY-Based Nanomaterials—Sensing and Biomedical Applications

Cancerous diseases are rightfully considered among the most lethal, which have a consistently negative effect when considering official statistics in regular health reports around the globe. Nowadays, metallic nanoparticles can be potentially applied in medicine as active pharmaceuticals, adjustable carriers, or distinctive enhancers of physicochemical properties if combined with other drugs. Boron dipyrromethene (BODIPY) molecules have been considered for future applications in theranostics in the oncology field, thus expanding the potential of conceivable applicability. Hence, taking into account positive practical features of both metal-based nanostructures and BODIPY derivatives, the present study aims to gather recent results connected to BODIPY-conjugated metallic nanoparticles. This is with respect to their expediency in the diagnosis and treatment of tumor ailments as well as in sensing of heavy metals. To fulfill the designated objectives, multiple research documents were analyzed concerning the latest discoveries within the scope of BODIPY-based nanomaterials with particular emphasis on their utilization for diagnostical sensing as well as cancer diagnostics and therapy. In addition, collected examples of mentioned conjugates were presented in order to draw the attention of the scientific community to their practical applications, elucidate the topic in a consistent manner, and inspire fellow researchers for new findings.

Highly sensitive and selective photoelectrochemical aptasensing of di-2-ethylhexyl phthalate based on graphene quantum dots decorated TiO2 nanotube arrays

A photoelectrochemical (PEC) sensing platform for di-2-ethylhexyl phthalate (DEHP) was constructed using graphene quantum dots decorated TiO₂ nanotube arrays (GQDs-decorated TiO₂ NTs) as the transducer species and the anti-DEHP aptamer as the biological recognition element. GQDs were synthesized using the alkali-mediated hydrothermal method, and then anchored onto the TiO₂ NTs uniformly and intimately via pronounced electrostatic interaction. Coupling GQDs with TiO₂ NTs not only enhanced visible-light absorption, but promoted charge separation and transportation, exhibiting excellent photocurrent response, and PEC activity. Various means were conducted to explore morphologies, optical, structural and PEC properties of the materials. As an identification unit, the anti-DEHP aptamer molecules were immobilized on GQDs-decorated TiO₂ NTs using a cross-linking coupling method. The developed PEC sensing platform exhibits excellent sensing behavior for DEHP, and provides a low detection limit of 0.1 ng/L, high selectivity and stability. Meanwhile, its application in real environmental samples was evaluated and satisfying results were achieved. Thus, the established sensing platform provides a promising tool to detect DEHP in the environment.

Microwave-Assisted Vacuum Synthesis of TiO2 Nanocrystalline Powders in One-Pot, One-Step Procedure

A new method for fast and simple synthesis of crystalline TiO2 nanoparticles with photocatalytic activity was developed by carrying out a classic sol-gel reaction directly under vacuum. The use of microwaves for fast heating of the reaction medium further reduces synthesis times. When the solvent is completely removed by vacuum, the product is obtained in the form of a powder that can be easily redispersed in water to yield a stable nanoparticle suspension, exhibiting a comparable photocatalytic activity with respect to a commercial product. The present methodology can, therefore, be considered a process intensification procedure for the production of nanotitania.

A photo-renewable ZIF-8 photo-electrochemical sensor for the sensitive detection of sulfamethoxazole antibiotic

Electroanalysis is an effective monitoring method for organic pollution in environmental samples. However, chemical fouling with the formation of non-conductive fouled films easily occurs on the surface of the electrode during organic pollution detection that would inactivate the electrode and affect the detecting sensitivity of organic pollution. In this work, we found that zeolitic imidazolate framework-8 (ZIF-8) electrode can achieve effective degradation of non-conductive fouled films under the light illumination during electrochemical detection of some typical organic pollution (sulfamethoxazole (SMX), Bisphenol A (BPA) and diclofenac sodium (DS)). Profiting from the charge transfer capability and photoelectric characteristics, ZIF-8 electrode exhibits a lower detection limitation for organic pollution detection and superior regeneration property. The nice detection and superior regenerated property are mainly due to non-selective superoxide radical (·O₂^-) and hydroxyl radicals (·OH) mediation produced by ZIF-8 electrode under light illumination that can mineralize anodic fouled products and resume surface reactive sites. Compared with the single electrochemical determination, photo-assisted electroanalysis provides a stable monitoring and a renewable pathway for practical applications.

Cobalt Phthalocyanine-Ionic Liquid Composite Modified Electrodes for the Voltammetric Detection of DNA Hybridization Related to Hepatitis B Virus

In this study, cobalt phthalocyanine (CoPc) and ionic liquid (IL) modified pencil graphite electrodes (PGEs) were designed and implemented to detect sequence-selective DNA hybridization related to the Hepatitis B virus (HBV). The surface characterization of CoPc-IL-PGEs was investigated by scanning electron microscopy (SEM), and the electrochemical behavior of electrodes were studied by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The voltammetric detection of hybridization was investigated by evaluating the guanine oxidation signal, measured by differential pulse voltammetry (DPV) technique. The implementation of our biosensor to serum samples was also examined using fetal bovine serum (FBS). The detection limit was established as 0.19 µg/mL in phosphate buffer solution (PBS) (pH 7.40) and 2.48 µg/mL in FBS medium. The selectivity of our assay regarding HBV DNA hybridization in FBS medium was tested in the presence of other DNA sequences. With this aim, the hybridization of DNA probe with non-complementary (NC) or mismatched DNA sequence (MM), or in the presence of mixture samples containing DNA target NC (1:1) or DNA target MM (1:1), was studied based on the changes in guanine signal.

Sodium Alginate Micelle-Encapsulating Zinc Phthalocyanine Dye-Sensitized Photoelectrochemical Biosensor with CdS as the Photoelectric Material for Hg2+ Detection

A simple and selective photoelectrochemical (PEC) biosensor was constructed for Hg²⁺ detection based on zinc phthalocyanine (ZnPc) dye-sensitized CdS using alginate not only as a carrier but also as a binder. First, CdS as a photoactive material was in situ modified on the electrode surface using a rapid and simple electrodeposition to obtain an initial photocurrent signal. Second, ZnPc was loaded in the amphiphilic alginate micelle and then was coated onto the CdS film surface via alginate as the binder. The photocurrent was subsequently enhanced due to the favorable dye sensitization effect of ZnPc to CdS. Finally, the thymine-rich probe DNA was immobilized on the modified ITO surface via coupling reaction between the carbonyl groups of the amphiphilic polymer and the amino groups of the probe DNA. In the presence of Hg²⁺, the thymine-Hg²⁺-thymine (T-Hg²⁺-T) structure was formed due to the specific bond of Hg²⁺ with thymine, resulting in the decrease of photocurrent due to the increase of steric hindrance on the modified electrode surface. The proposed PEC biosensor for Hg²⁺ detection possessed a wide linear range from 10 pM to 1.0 μM with a detection limit of 5.7 pM. This biosensor provides a promising platform for detecting other biomolecules of interest.

Amplified photocurrent signal for fabricating photoelectrochemical sulfadimethoxine aptasensor based on carbon nitride photosensitization with visible/near-infrared light responsive zinc phthalocyanine

Developing effective analytical method for sulfadimethoxine (SDM) detection is highly desirable and vitally crucial for protecting environment safety and human health. Herein, a highly selective and sensitive photoelectrochemical (PEC) aptasensor for accurate detection of SDM was proposed, which employed zinc phthalocyanine/graphitic carbon nitride (ZnPc/CN) nanocomposite as photosensitive material. The ZnPc/CN nanocomposite was constructed by modification of CN nanosheet with visible/near-infrared light responsive photosensitizer ZnPc. The introduction of ZnPc into CN exhibited amplified PEC response, which was 5.7 and 18.3 times than pure ZnPc and CN, attributed to the enhanced light harvesting ability and improved photoelectric conversion efficiency of such nanocomposite. By using ZnPc/CN and sulfadimethoxine (SDM) aptamer as PEC response material and specific probe, a PEC aptasensor was established for SDM detection. The aptamer was connected to the surface of chitosan/ZnPc/CN/ITO through the formation of phosphoramidate bonds between the amino group of the chitosan and phosphate group of the aptamer at 5' end. The fabricated aptasensor displayed good detection linearity of 0.1 ~ 300 nM and low detection limit of 0.03 nM (S/N = 3) under optimized conditions, and the potential applicability of the PEC aptasensor was confirmed by detecting SDM in milk powder samples.

Latest Advances in Determination of Bisphenols with Nanomaterials, Molecularly Imprinted Polymers and Aptamer Based Electrochemical Sensors

Contamination of environmental sources such as soils, sediments and rivers and human exposure caused by several endocrine disrupting compounds (EDCs) are considered as the most challenging issues of today's world. EDCs cover a wide variety of compounds ranging from phthalates to parabens and bisphenols (BPs) are the leading group among them. BPs are widely used during the production of different plastic materials such as food and beverage containers, toys, medical equipment and baby bottles that we use in every aspect of our lives. BPs may migrate from those products to different media under certain conditions and this situation causes chronic exposure for humans and other creatures in the environment. Especially bisphenol A (BPA) and its other analogues such as bisphenol F, bisphenol S and tetrabromobisphenol that have similar structures and are preferred as alternatives to BPA cause harmful adverse effects such as endocrine disruption, neurotoxicity, genotoxicity and cytotoxicity. There are legal restrictions and prohibitions by the European Union (EU) in order to prevent possible harmful effects. Therefore, it is important to develop highly sensitive, fast, easy to use and cheap sensors for the determination of BPs in biological, environmental and commercial samples. Electrochemical sensors, which are one of the most widely, used analytical techniques, provide these conditions. Additionally, it is possible to enhance the performance of electrochemical sensors with nanomaterials, molecularly imprinted polymers or aptamer based technologies. This review aims to give comprehensive information about BPs with summarizing most recent applications of electrochemical sensors for their determination in different samples.

Fabrication of copper phthalocyanine/reduced graphene oxide nanocomposites for efficient photocatalytic reduction of hexavalent chromium

Copper(II) phthalocyanine (CuPc) and non-peripheral octamethyl-substituted copper(II) phthalocyanine (N-CuMe₂Pc) were combined with reduced graphene oxide (rGO) via a precipitation method to form CuPc/rGO and N-CuMe₂Pc/rGO nanocomposites, respectively. CuPc nanorods are distributed on rGO, and N-CuMe₂Pc exists as nanorods and nanoparticles on rGO. The Cr(VI) removal ratio of N-CuMe₂Pc/rGO exposed in simulated sunlight is 99.0% with a fast photocatalytic reaction rate of 0.0320 min^-1, which is approximately 1.5 times faster than that of CuPc/rGO (0.0215 min^-1) and far surpasses that of pristine phthalocyanine and rGO. As an electron acceptor, rGO can suppress the recombination of photo-induced electron-hole pairs and also can provide a large surface area for Cr(VI) removal, both of which are beneficial to the reducing capacity of the nanocomposites. The higher removal efficiency of N-CuMe₂Pc/rGO compared with that of CuPc/rGO is attributed to the higher specific surface area, higher light harvesting, higher conductivity and more negative lowest unoccupied molecular orbital level of N-CuMe₂Pc/rGO. The N-CuMe₂Pc/rGO nanocomposite shows excellent photochemical recyclability which is essential for application in wastewater treatment.

Sensitive, simple and fast voltammetric determination of pesticides in juice samples by novel BODIPY-phthalocyanine-SWCNT hybrid platform

The present work describes the first synthesis of novel asymmetric zinc (II) phthalocyanine (ZnPc) including three boron dipyrromethene (BODIPY) and one ethyloxy azido moieties. Moreover, single walled carbon nanotube (SWCNT) surface was functionalized by this ZnPc containing BODIPY; using the azide-alkyne Huisgen cycloaddition (Click) reaction to obtain SWCNT-ZnPc hybrid material. Structural, thermal and morphological characterizations of both ZnPc and SWCNT-ZnPc hybrid were carried out in-depth by spectroscopic, thermal and microscopic techniques. In this study, the synthesized SWCNT-ZnPc material was decorated on composite glassy carbon electrode (GCE) by means of an easy and a practical drop cast method. The modified electrode was tested as a non-enzymatic electrochemical sensor in various common pesticides such as methyl parathion, deltamethrin, chlorpyrifos and spinosad. Electrochemical behavior of non-enzymatic electrode (GCE/SWCNT-ZnPc) was determined via cyclic voltammetry and differential pulse voltammetry. The non-enzymatic sensor demonstrated high selectivity for methyl parathion in a wide linear range (2.45 nM-4.0 × 10^-8 M), low limit of detection value (1.49 nM) and high sensitivity (0.1847 μA nM^-1). Also, the developing non-enzymatic sensor exhibited good repeatability (RSD = 2.3% for 10 electrodes) and stability (85.30% for 30 days). Validation guidelines by HPLC and statistical analysis showed that the proposed voltammetric method were precise, accurate, sensitive, and can be used for the routine quality control of methyl parathion determination in juice samples.

A synergetic and sensitive physostigmine pesticide sensor using copper complex of 3D zinc (II) phthalocyanine-SWCNT hybrid material

2,3,9,10,16,17,23,24-Octakis (4-methyl-2,6-bis((prop-2-yn-1-yloxy)methyl)phenoxy) phthalocyaninato zinc(II) (Pc) bearing sixteen terminal ethynyl groups was synthesized and attached to SWCNT (Single-walled carbon nanotube) covalently to obtain three dimensional porous hybrid material (SWCNT-Pc 3D) and its copper complex (Cu-SWCNT-Pc 3D). The structural characterization and electrochemical sensor features of the Cu-SWCNT-Pc hybrid towards to physostigmine pesticide were performed. A fast, direct and suitable determination method for physostigmine detection was offered. The designed sensor, Cu-SWCNT-Pc 3D/GCE (glassy carbon electrode) shows sensitivity ca 1.8, 4.3 and 2.8 times more than that of SWCNT/GCE, SWCNT-Pc-noncovalent/GCE and SWCNT-Pc 3D/GCE in terms of peak heights while bare and Pc/GCE had almost no voltammetric response to 2 μM physostigmine in PBS at a pH of 7.0. The limit of detection and quantification of physostigmine determination with Cu-SWCNT-Pc 3D/GCE were found to be 53 and 177 nM in the range of 0.1-4.8 μM, respectively. This study demonstrated that the modification of the GCE with Cu-SWCNT-Pc 3D as an electrochemical sensor was acted as catalytic role toward physostigmine presence of other interfering pesticides as high sensitivity and selectivity. The electrochemical determination of physostigmine in real samples was performed under the optimized conditions, also accuracy of the electrochemical determination method was evaluated with HPLC as a standard determination method.

Au Quantum Dot/Nickel Tetraminophthalocyanaine-Graphene Oxide-Based Photoelectrochemical Microsensor for Ultrasensitive Epinephrine Detection

Owing to the importance of epinephrine as a neurotransmitter and hormone, sensitive methods are required for its detection. We have developed a sensitive photoelectrochemical (PEC) microsensor based on gold quantum dots (Au QDs) decorated on a nickel tetraminophthalocyanine-graphene oxide (NiTAPc-Gr) composite. NiTAPc was covalently attached to the surface of graphene oxide to prepare NiTAPc-Gr, which exhibits remarkable stability and PEC performance. In situ growth of Au QDs on the NiTAPc-Gr surface was achieved using chemical reduction at room temperature. The synthesized materials were characterized by Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, and electrochemical impedance spectroscopy. Au QDs@NiTAPc-Gr provided a much greater photocurrent than NiTAPc-Gr, making it suitable for the ultrasensitive PEC detection of epinephrine. The proposed PEC strategy exhibited a wide linear range of 0.12-243.9 nM with a low detection limit of 17.9 pM (S/N = 3). Additionally, the fabricated PEC sensor showed excellent sensitivity, remarkable stability, and good selectivity. This simple, fast, and low-cost strategy was successfully applied to the analysis of human serum samples, indicating the potential of this method for clinical detection applications.

Efficient TiO2/SubPc photocatalyst for degradation of organic dyes under visible light

Degrade pollutants under visible light.

The design and growth of peanut-like CuS/BiVO4 composites for photoelectrochemical sensing

In this study, the CuS/BiVO₄-X (where X represents the mass percentage of CuS associated with CuS/BiVO₄; X = 2%, 5% and 7%) p–n heterostructures were fabricated using a two-step hydrothermal method.

Hydrogen bonding assisted formation of sandwich-type titanium-containing heteropolymolybdates: water-soluble and photoelectroactive

Two water-soluble titanium-containing polyoxomolybdates have been synthesized by means of a hydrogen bonding assisted strategy. Their applications in the photoelectrochemical sensing of bisphenol A in aqueous solution were also investigated.

Ultrasensitive and visible light-responsive photoelectrochemical aptasensor for edifenphos based on Zinc phthalocyanine sensitized MoS2 nanosheets

Developing a simple, rapid detection method for the analysis of edifenphos (EDI) is crucial due to its residue is harmful to acetylcholinesterase on the human cellular system, and cause a lot of complications. Herein, we synthesized visible light-responsive MoS₂ nanosheets decorated with Zinc phthalocyanine (ZnPc) nanoparticles (ZnPc/n-MoS₂). Due to the sensitization of ZnPc nanoparticles, the resulting ZnPc/n-MoS₂ exhibited narrower energy bandgap and efficient charge transfer. Especially, the carrier lifetime of ZnPc/n-MoS₂ is 2 more times longer than n-MoS₂, and the photocurrent intensity of ZnPc/n-MoS₂ is 24 times of n-MoS₂ and 22 times of ZnPc nanoparticles under visible light irradiation. Further, a visible light-responsive ultrasensitive photoelectrochemical (PEC) aptasensor for selectivity recognition of EDI was triumphantly established by using EDI aptamer as a biorecognition element, which exhibited a wide linear ranking from 5 ng L^-1 to 10 μg L^-1 (R² = 0.996) and a low detection limit of 1.667 ng L^-1 (S/N = 3). The splendid performance of the ZnPc/n-MoS₂ nanosheet ultrasensitive sensing platform can be applied to detect the concentration of EDI in food, biomedical and environmental analysis.

Highly-sensitive and selective determination of bisphenol A in milk samples based on self-assembled graphene nanoplatelets-multiwalled carbon nanotube-chitosan nanostructure

Graphene nanoplatelets (GNPs), multiwalled carbon nanotube (MWCNTs) and chitosan (CS) were self-assembled by a facile one-step hydrothermal reaction to obtain novel MWCNTs-CS enfolded GNPs (GNPs-MWCNTs-CS) composite. Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), UV-visible (UV-vis) absorption spectroscopy and zeta potential analysis were employed to characterize the morphology, surface composition, interaction, surface charge and stability of the GNPs-MWCNTs-CS composite. The electrochemical behaviors of GNPs-MWCNTs-CS composite modified glassy carbon electrode (GNPs-MWCNTs-CS/GCE) were investigated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The GNPs-MWCNTs-CS/GCE was used for fast and high sensitive determination of bisphenol A (BPA) by differential pulse voltammetry (DPV). Under the optimum conditions, the calibration curve obtained is linear for the current versus the BPA concentration in the range 0.1-100 μM with a detection limit of 0.05 nM (signal-to-noise ratio of 3, S/N = 3). The between-sensor reproducibility was 1.29% (n = 6) for 0.04 mM BPA. The proposed GNPs-MWCNTs-CS/GCE based sensor showed high resistance to interference, good repeatability and excellent reproducibility. Trace BPA in milk samples could also be reliably determined.

Integrated Au/TiO2 Nanostructured Photoanodes for Photoelectrochemical Organics Degradation

In this work, hierarchical Au/TiO2 nanostructures were studied as possible photoanodes for water splitting and bisphenol A (BPA) oxidation. TiO2 samples were synthetized by Pulsed Laser Deposition (PLD), while Au nanoparticles (NPs) were differently dispersed (i.e., NPs at the bottom or at the top of the TiO2, as well as integrated TiO2/Au-NPs assemblies). Voltammetric scans and electrochemical impedance spectroscopy analysis were used to correlate the morphology of samples with their electrochemical properties; the working mechanism was investigated in the dark and in the presence of a light radiation, under neutral pH conditions towards the possible oxidation of both bisphenol A (BPA) and water molecules. Different behavior of the samples was observed, which may be attributed mainly to the distributions of Au NPs and to their dimension as well. In particular, the presence of NPs at the bottom seems to be the crucial point for the working mechanism of the structure, thanks to scattering effects that likely allow to better exploit the radiation.

Facile fabrication of visible light photoelectrochemical immunosensor for SCCA detection based on BiOBr/Bi2S3 heterostructures via self-sacrificial synthesis method

A novel visible light photoelectrochemical immunosensor based on BiOBr/Bi₂S₃ heterostructures was fabricated to detect squamous cell carcinoma antigen (SCCA). Bi₂S₃ nanoparticles formed on the BiOBr microflowers by the self-sacrificial synthesis method based on the facile reaction between BiOBr and S^2- ions. The BiOBr/Bi₂S₃ composites exhibited excellent visible light photoelectrochemical activity, when ascorbic acid (AA) was employed as a perfect electron donor. The photocurrent intensity of BiOBr/Bi₂S₃ modified ITO electrode arrived at around 20 µA, which was approximately 30 times than that of pure BiOBr. Dopamine formed easily polydopamine film via self-polymerization on the surface of BiOBr/Bi₂S₃ composites to immobilize SCCA antibody. Under the optimal condition, this photoelectrochemical immunosensor realized the ultrasensitive determination of SCCA. With the logarithm of SCCA concentration in the range of 0.001-75 ng mL^-1, the specific binding between SCCA and antibody led to the linearly decrease of photocurrent signal with a low detection limit of 0.3 pg mL^-1 (S/N = 3). This facilely constructed photoelectrochemical immunosensor maybe have promising practical application in photocatalysis, analytical detection and biosensor, etc.

Photoelectrochemical biosensor for protein kinase A detection based on carbon microspheres, peptide functionalized Au-ZIF-8 and TiO2/g-C3N4

In this work, a novel and sensitive photoelectrochemical (PEC) strategy was designed for protein kinase A (PKA) detection, comprising carbon microsphere (CMS) modified ITO electrode, TiO₂ as the phosphate group recognition material and graphite-carbon nitride (g-C₃N₄) as photoactive material. For the first time, gold nanoparticle decorated zeolitic imidazolate frameworks (Au-ZIF-8) was employed to fabricate biosensor for PKA activity assay with the function of substrate peptide immobilization and signal amplification. Firstly, substrate peptides were assembled on the Au-ZIF-8/CMS/ITO surface through the covalent bonding between the gold nanoparticles (AuNPs) and sulfydryl groups of the peptides. Then, in the presence of ATP, phosphorylation of the substrate peptide was achieved under PKA catalysis. Finally, TiO₂-g-C₃N₄ composites were further modified on the electrode surface based on bonding between TiO₂ and phosphate groups created via phosphorylation of the peptide (yielding TiO₂-g-C₃N₄/P-peptide/Au-ZIF-8/CMS/ITO), which is different with our previous work by directly immobilizing g-C₃N₄ composite on electrode surface. The developed method showed a wide linear range from 0.05-50 U mL^-1. The detection limit was 0.02 U mL^-1 (S/N = 3). The constructed biosensor exhibited high detection specificity for PKA. In addition, the wide applicability of this biosensor was demonstrated by evaluating the inhibition ability of ellagic acid towards PKA.

A novel sandwich-type photoelectrochemical sensor for SCCA detection based on Ag2S-sensitized BiOI matrix and AucorePdshell nanoflower label for signal amplification

Signal amplification was fulfilled for the interaction between BiOI/Ag₂S and Au_cPd_s.