Microchimica Acta最新文献

{"title":"Capillary-driven distance-based paper analytical devices for albumin protein and glucose quantification in human whole blood","authors":"Kawin Khachornsakkul,&nbsp;Thithawat Trakoolwilaiwan,&nbsp;Ruben Del-Rio-Ruiz,&nbsp;Sameer Sonkusale,&nbsp;Tapparath Leelasattarathkul","doi":"10.1007/s00604-025-07079-z","DOIUrl":"10.1007/s00604-025-07079-z","url":null,"abstract":"<div><p>This study presents a simple and inexpensive distance-based paper analytical device (dPAD) for plasma separation from whole blood samples and its application in monitoring albumin protein and glucose levels using colorimetric and fluorescent distance methods. The developed dPAD consists of a sample zone, a separation zone with hydrophobic wax-patterned lines, a pretreatment zone, and a straight zone channel pre-deposited with chemical reagents for both albumin protein and glucose quantification. Plasma separation relies on the capillarity-driven different flow velocities of blood cells and plasma with varying hydrophilicity in the paper channel. Remarkably, the blood cells are trapped in the separation channel of the device, while plasma can be separated and subsequently flow with a buffer solution to the detection zone by capillary force. Target analyte in plasma content then reacts with its specific reagents, resulting in the change in the color or fluorescent distance signal. Our sensor exhibited remarkable accuracy and precision for the detection of albumin protein and glucose in whole blood samples with an acceptable recovery range between 99.94 and 101.65% and the highest relative standard deviation (RSD) of 4.49%. Furthermore, the results indicated no significant differences between our method and conventional methods for albumin protein and glucose determination in whole blood samples. Additionally, to the best of our knowledge, this method is the first time for the development of the fluorescent dPAD sensor for glucose monitoring. It is also the first demonstration to use a dPAD sensor for the direct detection of both albumin protein and glucose levels in whole blood. Hence, despite its simplicity, the concept offers a more cost-effective and accessible method for plasma separation from whole blood and subsequent albumin protein or and glucose detection. Moreover, it can be extended for further advancements in POC analytical sensing. </p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":705,"journal":{"name":"Microchimica Acta","volume":"192 4","pages":""},"PeriodicalIF":5.3,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143629697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel smartphone-mediated ratiometric fluorescence imprinting sensor based on boric acid-functionalized Eu-MOF for the detection of horseradish peroxidase","authors":"Minghao Ma,&nbsp;Wei Hu,&nbsp;Shengdong Luo,&nbsp;Fubin Pei,&nbsp;Wu Lei,&nbsp;Jiang Wang,&nbsp;Zhaoyang Tong,&nbsp;Bing Liu,&nbsp;Bin Du,&nbsp;Qingli Hao,&nbsp;Xihui Mu","doi":"10.1007/s00604-025-07074-4","DOIUrl":"10.1007/s00604-025-07074-4","url":null,"abstract":"<div><p> Horseradish peroxidase (HRP) was used as a model glycoprotein, and a molecularly imprinted ratiometric fluorescence sensor based on a smartphone (NEB@MIP) was constructed using the sol–gel method for the fluorescence and visual detection of HRP. The sensor consisted of boronic acid-functionalized metal–organic frameworks (Eu-MOF-B(OH)₂) and nitrogen-doped carbon dots (N-CDs). The Eu-MOF-B(OH)₂ surface can not only load abundant N-CDs but also covalently bind with HRP through its boronic acid groups. The NEB@MIP exhibited two fluorescence emission peaks at 450 nm and 616 nm. When HRP was present, the fluorescence was quenched due to the internal filtering effect (IFE), but the quenching of N-CDs was more pronounced. Furthermore, the concentration of HRP in the range 0.05–10 µM showed a good linear relationship with the ratio of fluorescence intensity at 616 nm and 450 nm, with a detection limit (LOD) of 0.01 µM. Meanwhile, the sensor displayed a noticeable change in fluorescence color under different concentrations of HRP targets. Moreover, the sensor achieved satisfactory results in detecting simulated real samples, with recoveries ranging from 92.0% to 98.5% and RSDs between 1.5% and 3.3%. The detection platform based on the smartphone also performed well when detecting HRP in simulated real samples. Thus, this work provided a new approach for the portable detection of HRP. The method provides a new idea for the combination of ratiometric fluorescence molecular imprinting of glycoproteins and the portable detection platform of smart phones.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":705,"journal":{"name":"Microchimica Acta","volume":"192 4","pages":""},"PeriodicalIF":5.3,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143612237","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Significantly improved catalytic activity of copper nanocrystal by introducing Ti3C2TX and arginine and serine-functionalized graphene quantum dot for colorimetric detection of H2O2","authors":"Ji Min,&nbsp;Li Ruiyi,&nbsp;Li Zaijun","doi":"10.1007/s00604-025-07027-x","DOIUrl":"10.1007/s00604-025-07027-x","url":null,"abstract":"<div><p>Copper nanocrystal has been widely used as nanozyme for construction of optical sensing platforms because of low cost, special catalysis, and high stability. However, low catalytic activity limits further applications in bioanalysis. This study reports one way for improving the catalytic activity of copper nanocrystal by introducing Ti₃C₂T_X and arginine and serine-functionalized graphene quantum dot (RSGQD). Cu²⁺ was reduced by RSGQD to produce copper nanocrystal, which was immobilized on Ti₃C₂T_X sheet via π-π stacking and self-assembly. The resulted Ti₃C₂T_X/Cu-RSGQD shows a three-dimensional structure composing of small copper nanocrystals with an average particle size of 18.1 ± 1.7 nm and Ti₃C₂T_X sheets. The introduction of Ti₃C₂T_X and RSGQD improves the catalytic activity due to good conductivity of Ti₃C₂T_X and formation of Ti₃C₂T_X/RSGQD/Cu Schottky heterojunction. The peroxidase-like and oxidase-like specific activities reach 591.61 U mg⁻¹ and 105.2 U mg⁻¹. Based on the catalysis of Ti₃C₂T_X/Cu-RSGQD towards oxidation of 3,3′,5,5′-tetramethylbenzidine into a blue product, a sensitive method was developed for colorimetric detection of H₂O₂. The absorbance linearly increases with increasing H₂O₂ concentration between 0 and 50 μM with a detection limit of 0.0032 μM (S/N = 3). The sensitivity is better than that of other reported analytical methods. It has been contentedly applied in colorimetric detection of H₂O₂ in food.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":705,"journal":{"name":"Microchimica Acta","volume":"192 4","pages":""},"PeriodicalIF":5.3,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602367","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A sensitive electrochemical biosensor based on Exo III cyclic amplification strategy for Phaeocystis globosa detection","authors":"Hongjie Liu,&nbsp;Hao Fu,&nbsp;Yibo Zhang,&nbsp;Shaopeng Wang,&nbsp;Kedi Yang,&nbsp;Liwei Wang","doi":"10.1007/s00604-025-07095-z","DOIUrl":"10.1007/s00604-025-07095-z","url":null,"abstract":"<p><i>Phaeocystis globosa</i> (<i>P. globosa</i>), a main culprit of harmful algal blooms (HABs), is highly prone to blocking the inlet filter screens of nuclear power cold sources, thus posing a significant threat to nuclear power safety. However, existing methods for <i>P. globosa</i> detection fail to achieve rapid and on-site monitoring of single-cell densities prior to bloom outbreaks, limiting timely defensive measures. In this study, we developed a novel biosensor platform for efficient <i>P. globosa</i> detection, leveraging an Exo III-assisted signal amplification strategy to significantly enhance sensitivity and selectivity. The biosensor achieved an ultra-low limit of detection (LOD) of 268.91 fg µL⁻¹ (3119 cells L⁻¹), far below the benchmark concentration for <i>P. globosa</i> blooms (10⁷ cells L⁻¹), and demonstrated a wide linear detection range from 500 fg µL⁻¹ to 10 ng µL⁻¹. Furthermore, the biosensor’s accuracy and reliability were validated through comparative analysis with droplet digital PCR (ddPCR) using actual samples from the Beibu Gulf of China, revealing a low risk of <i>P. globosa</i> blooms in the region at the sampling time. This study represents a significant advancement in HAB monitoring by providing a highly sensitive, rapid, and field-deployable tool for early warning of <i>P. globosa</i> blooms. The biosensor’s innovative design and performance address critical gaps in current detection methods, offering practical implications for safeguarding coastal nuclear power facilities and protecting marine ecosystems.</p>","PeriodicalId":705,"journal":{"name":"Microchimica Acta","volume":"192 4","pages":""},"PeriodicalIF":5.3,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143612128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A multifunctional Pt/DMSN nanozyme-based colorimetric-fluorescence sensing platform for breast cancer detection","authors":"Xinrui Xue,&nbsp;Fang Zheng,&nbsp;Yujia Luo,&nbsp;Wenyu Chen,&nbsp;Yuanyuan Gao,&nbsp;Kun Wei","doi":"10.1007/s00604-025-07082-4","DOIUrl":"10.1007/s00604-025-07082-4","url":null,"abstract":"<div><p> Nanozyme-linked immunosorbent assay has emerged as a promising strategy for sensitive biosensing. However, the catalytic activity and stability of nanozymes affect the accuracy of immunosorbent assays. In this study, we synthesized a Pt/DMSN nanozyme with peroxidase-mimicking activity, which effectively catalyzed the oxidation of peroxidase substrate 3,3',5,5'-tetramethylbenzidin (TMB) in the presence of hydrogen peroxide. Capitalizing on its peroxidase-like activity, the Pt/DMSN nanozyme was functionalized with dual-fluorescent recognition elements (HER2-mAbs and sk6Ea aptamers) to establish a nanozyme-linked immunosorbent assay platform, which exhibited catalytic stability and substrate affinity comparable to horseradish peroxidase. The resulting Multi-Pt/DMSN platform was used to selectively distinguish HER2-positive breast cancer cells from luminal A, triple-negative breast cancer subtypes, and non-neoplastic cells, achieving a detection limit of 50 HER2-positive cells within 30 min. The combination of robust enzyme-like activity and tumor-targeting properties enables fluorescence imaging, providing dual-mode diagnostic functionality. This work presents a prospective platform for differentiating breast cancer subtypes in early diagnosis.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":705,"journal":{"name":"Microchimica Acta","volume":"192 4","pages":""},"PeriodicalIF":5.3,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A smartphone-based portable electrochemical sensor enabled ultrasensitive detection of paclitaxel in serum and injection samples","authors":"Ruo-Yu Yang,&nbsp;Jin-Hua Wang,&nbsp;Zi-Wei Yu,&nbsp;Yun-Ting Chen,&nbsp;Mei-Juan Wu,&nbsp;Pin-Fang Huang,&nbsp;Meng-Meng Liu","doi":"10.1007/s00604-025-07085-1","DOIUrl":"10.1007/s00604-025-07085-1","url":null,"abstract":"<div><p>A point-of-care testing platform, consisting of smartphone, miniature electrochemical workstation, and screen-printed carbon electrode (SPCE) modified by gold nanoparticle (AuNPs) and multi-walled carbon nanotubes (MWCNTs), is fabricated for the ultrasensitive detection of paclitaxel (PTX) in human serum and injection solution. To enhance conductivity of the sensing system, MWCNTs concentration and AuNPs electrodeposition time were optimized. The AuNPs/MWCNTs effectively increase the working electrode area of SPCE by a factor of 1.46, contributing to improved electrochemical performance. The steps of electrode surface modification and the characterization of AuNPs/MWCNTs/SPCE were investigated by differential pulse voltammetry, impedance spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The sensor shows good linearity between current response and PTX concentration in 0.2 M phosphate buffer at pH = 7.4 (0.05–10 μM, with a limit of detection (LOD) of 1.7 nM) and human serum (0.5–30 μM and a LOD of 3.6 nM). The recoveries range from 89.91 to 103.36% and 91.42 to 103.73% in human serum and injection solution, respectively, with satisfactory relative standard deviation. Moreover, the sensor has excellent stability during 8 weeks and exhibits outstanding specificity and reproducibility towards PTX detection, providing a possible option for PTX determination in practical application such as therapeutic drug monitoring and drug quality control.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":705,"journal":{"name":"Microchimica Acta","volume":"192 4","pages":""},"PeriodicalIF":5.3,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143612127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ratiometric fluorescence quantification of folic acid utilizing D-penicillamine-based carbon dots in conjunction with glutathione S-transferase-Au nanoclusters","authors":"Mengyan Zhou,&nbsp;Zhihui Zhang,&nbsp;Qi Zheng,&nbsp;Mingdi Yu,&nbsp;Mengxu Si,&nbsp;Sirui Wu,&nbsp;Yanan Zhang,&nbsp;Shushu Ding,&nbsp;Ding-Yi Fu","doi":"10.1007/s00604-025-07062-8","DOIUrl":"10.1007/s00604-025-07062-8","url":null,"abstract":"<div><p>A novel ratiometric fluorescent nanohybrid probe was constructed for sensitive and selective determination of folic acid (FA) based on blue D-penicillamine-based carbon dots (CDs) and red glutathione S-transferase-Au nanoclusters (GST-AuNCs). Upon the excitation of 380 nm, the obtained CDs-NCs possessed two distinct emission peaks at 465 and 665 nm. The fluorescence intensity at 465 nm was incrementally enhanced with the addition of FA attributed to the hydrogen bonds formation, while the fluorescence intensity at 665 nm was quenched caused by the electronic interaction and the inner filter effects. The fluorescence intensity ratio (<i>I</i>₄₆₅<i>/I</i>₆₆₅) exhibited good linear correlation with FA concentrations in the range 10∼90 μM, and the limit of detection (LOD) was 0.63 μM. Notably, the corresponding fluorescent color changed from red to blue, which could be distinguished by naked eyes. On account of the excellent biocompatibility, the CDs-NCs were further successfully used for bioimaging and intracellular FA detection. Furthermore, the real sample analyses confirmed that the proposed nanoprobe could be expanded as a versatile platform for FA detection in practical applications.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":705,"journal":{"name":"Microchimica Acta","volume":"192 4","pages":""},"PeriodicalIF":5.3,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143612183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An electrochromism-equipped enzymatic biofuel cell system combined with hollow microneedle array for self-powered glucose sensing in interstitial fluid","authors":"Nan Xiao,&nbsp;Haotian Li,&nbsp;Zheyuan Fan,&nbsp;Fangfang Luo,&nbsp;Dingxi Lu,&nbsp;Wen Sun,&nbsp;Zhanhong Li,&nbsp;Zifeng Wang,&nbsp;Yutong Han,&nbsp;Zhigang Zhu","doi":"10.1007/s00604-025-07096-y","DOIUrl":"10.1007/s00604-025-07096-y","url":null,"abstract":"<div><p> A disposable, self-powered enzymatic biofuel cell (BFC) sensor integrated with a hollow microneedle array (HMNA) for glucose monitoring in interstitial fluid (ISF) is reported. The HMNA enables painless and minimally invasive ISF extraction. The BFC uses dehydrogenase (GDH) in conjunction with NAD⁺, diaphorase (DI), and vitamin K₃ (VK₃) serving as electron transfer mediators as the anode catalyst and Prussian blue (PB) as the electrochromic cathode. Glucose oxidation at the anode generates electrons that cause PB to change the color at the cathode, allowing for visual glucose concentration determination. The open-circuit potential (OCP) of the sensor is 0.14 V, with a maximum power density of 0.07 µW·cm⁻², at a glucose concentration of 14 mM. The sensor shows good performance in glucose sensing with a linear relationship between the R/B ratio and glucose concentrations ranging from 0 to 14 mM. This disposable device offers a promising approach for non-invasive and self-powered glucose sensing.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":705,"journal":{"name":"Microchimica Acta","volume":"192 4","pages":""},"PeriodicalIF":5.3,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143594638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water-stable Eu(III) coordination polymer-based ratiometric fluorescence sensor integrated with smartphone for onsite monitoring of doxycycline hydrochloride in milk","authors":"Cancan Zhang,&nbsp;Xiaochen Deng,&nbsp;Huanhuan Tan,&nbsp;Xiaoxin Zhang,&nbsp;Jiao Wu,&nbsp;Yuyang Zhao,&nbsp;Lingyan Zhao","doi":"10.1007/s00604-025-07081-5","DOIUrl":"10.1007/s00604-025-07081-5","url":null,"abstract":"<div><p>The widespread misuse of doxycycline hydrochloride (Dox) in livestock farming has necessitated the development of rapid and reliable methods for monitoring its residues in food products. Herein, a water-stable europium coordination polymer-Eu(C₂O₄)1.5(H₂O)ₙ (Eu-CP) with a layered structure was synthesized via a one-step hydrothermal approach. Leveraging its dual-emission properties (455 nm ligand-centered blue emission and 615 nm Eu(III)-based red emission), we engineered a ratiometric fluorescence sensor (I₆₁₅/I₄₅₅) for Dox detection. The sensing mechanism involves synergistic effects of the antenna effect and Dox@Eu-CP complexation, enabling selective Dox recognition with a wide linear range (10–100 μM) and a low detection limit (0.46 μM, S/N = 3). To facilitate onsite analysis, a smartphone-integrated platform was developed, translating the Dox concentration-dependent color transition (blue → red) into quantifiable R/G values via a custom Android application. Practical applicability was demonstrated in milk samples, achieving recoveries of 82.4–119.4% (fluorescence) and 87.8–113.3% (smartphone) with RSD &lt; 5%. This work pioneers the integration of lanthanide coordination polymers with portable digital detection, offering a green and visual strategy for antibiotic residue monitoring in food safety.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":705,"journal":{"name":"Microchimica Acta","volume":"192 4","pages":""},"PeriodicalIF":5.3,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A visual COD sensor based on the magnetically oriented graphite flake-enhanced photoelectrochromic effect","authors":"Bin Feng,&nbsp;Hongze Yang,&nbsp;Yanmei Zhang,&nbsp;Rui Jiang,&nbsp;Panpan Mou,&nbsp;Zhimei Wang,&nbsp;Guosong Chen,&nbsp;Liming Huang","doi":"10.1007/s00604-025-07088-y","DOIUrl":"10.1007/s00604-025-07088-y","url":null,"abstract":"<div><p>A visual chemical oxygen demand (COD) sensor was developed by electrodepositing Prussian blue (PB) on indium tin oxide (ITO) conductive glass to form an electrochromic layer, followed by the vertical alignment and immobilization of graphite flakes under a magnetic field. A TiO₂/g-C₃N₄ heterojunction photocatalyst was in situ integrated with the graphite flakes to enhance the performance. Under the irradiation of visible light, reductive substances in the water sample are oxidized by photogenerated holes from TiO₂/g-C₃N₄, while photogenerated electrons are conducted through the graphite flakes to the electrochromic layer, reducing PB to Prussian white (PW) and causing a color change. The RGB values of the captured image are used to calculate the total color difference, enabling visual quantification of COD. The overlapping of the photo-oxidation layer (POL) and the electrochromic reduction layer (EDL) shortens electron transport distances. Vertically aligned graphite flakes further reduce electron transport resistance, improving photogenerated electron efficiency and lowering the COD detection limit. Additionally, the alignment increases the sensor’s effective light-capture area and the photocatalyst loading capacity, expanding the measurement range to 3.2–320 mg/L. The sensor can be easily regenerated by simple cleaning and air oxidation within 1 h, allowing repeated use without interference from chloride ions. The relative standard deviation for repeated measurements and the relative error compared to standard methods are both around 10%, demonstrating good practical applicability.</p><h3>Graphical Abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":705,"journal":{"name":"Microchimica Acta","volume":"192 4","pages":""},"PeriodicalIF":5.3,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143602192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}