Open-ended experiment courses play a crucial role in cultivating practical skills， innovative thinking and scientific literacy of undergraduate students. In this project， an open-ended experiment was designed and implemented with the theme of quantitative detection of sulfur dioxide （SO2） gas pollutants using smartphone-based colorimetry. During the experiment， volatile SO₂ in samples was enriched using headspace single-drop microextraction. In the single-drop system， SO2 reacted with silver nanoparticles， inducing a distinct color change. SO2 concentration was quantified through colorimetric analysis using a smartphone as a portable detection platform. This experiment guided students to employ smartphones as a novel portable detection platform， inspiring the innovative application of diverse scientific tools. The design covered fundamental analytical chemistry skills， including calibration curve construction， sample quantification and colorimetric analysis. Advanced techniques， such as microextraction and nanoparticle-mediated color reactions， were also introduced. This open-ended experiment course enables undergraduates to understand the core principles of colorimetric analysis in environmental monitoring， fostering a comprehension of the close link between theory and practical techniques in real research contexts. Throughout the experiment， students experience both the rigor and creativity of scientific exploration， while recognizing the broader significance of scientific experimentation in environmental protection， societal development and national technological advancement. Consequently， the course facilitates the internalization of scientific spirit， social responsibility and professional mission， achieving a deep integration of professional competence with values-based education.

Copper(I)-driven colorimetric-fluorometric detection of triacetone triperoxide (TATP) using eco-friendly carbon dots.

A defect-engineered bimetallic MOF nanozyme with enhanced activity for colorimetric detection of acid phosphatase.

A colorimetric - ratiometric SERS dual-mode sensor based on magnetic COF nanoflowers is used for the detection of glucose in food.

Maintaining optimal health and preventing diabetes-related complications requires accurate and timely monitoring of blood glucose levels. In line with this, the present study focuses on developing an affordable, reliable, and precise Point-of-Care (POC) diagnostic platform for glucose detection by integrating microfluidic and colorimetric principles. The system employs a custom-fabricated microfluidic chip designed to facilitate efficient enzymatic color reactions using only ~20 μl of sample per microwell, achieving complete color development within 3-4 min. This chip is housed inside a compact, USB-powered 3D-printed imaging module equipped with a high-resolution fixed-focus camera, enabling consistent control over imaging parameters such as focal distance, camera alignment, and illumination conditions. The overall workflow is optimized for seamless compatibility with embedded systems or laptops, eliminating the dependency on smartphones or external calibration tools and making the setup well-suited for real-time diagnostic use in POC environments. A total of 1280 images, representing 16 glucose concentration levels ranging from 50 to 200 mg dl-1, were captured under standardized conditions, labelled according to known concentrations, and processed through uniform preprocessing steps. Engineered image features extracted from the preprocesses images were then analysed using supervised machine learning models, including Random Forest, Support Vector Machine (SVM), K-Nearest Neighbours (KNN), and a Feedforward Neural Network, to establish a robust predictive framework capable of delivering fast, consistent, and accurate glucose estimation for practical healthcare applications. Among the evaluated models, the Random Forest (RF) classifier achieved the highest cross-validation precision of 98% and an exceptional specificity approaching 100%. This clearly describes its ability to distinguish between different glucose concentration levels. Further, the confusion matrix and the ROC curve analysis have validated the model's reliability, with very minimal chances of misclassifications and a high mean AUC value of around 1. These results ensure the potential of the image-based glucose concentration estimation as a cost effective and a reliable, scalable solution for real time monitoring in various medical related industries.

Staphylococcus aureus, a major foodborne pathogen contaminating dairy products, threatens food safety and public health via food poisoning and severe infections such as bacteremia. Conventional culture-based methods are time-consuming, while advanced techniques need expensive equipment, limiting on-site use. To address this, we developed a novel magnetic mesoporous manganese oxide-like (MnOx) nanozyme probe (MMMNP) by integrating mesoporous MnOx nanozyme with oxidase-mimetic activity, Fe3O4 magnetic nanoparticles, and S. aureus-specific aptamers. The synthesis involved the preparation of hydrothermal Fe3O4, the synthesis of MnOx, and the construction of a composite with bond positions and electrostatic interactions. For detection, MMMNP mixed with samples underwent magnetic separation, followed by 3,3',5,5'-tetramethylbenzidine-triggered color reaction. The S. aureus (0-106 cfu·mL-1) inhibited probe activity, fading solution from deep blue to colorless. There was a good linear correlation (R2 = 0.980) between the shift of the absorbance peak at 652 nm and the logarithm of S. aureus concentration, with a limit of detection of 3.33 cfu·mL-1 for UV-visible detection and 1 × 102 cfu·mL-1 for naked-eye visual detection. The probe exhibited high specificity, with no response to interfering bacteria, and demonstrated good applicability in spiked milk (recovery: 86.84%-113.81%, relative SD <5%). Unexpectedly, lower detection limits and better linearity were also achieved in the milk samples. Preliminary tests confirmed magnetic MnOx's significant bacteriostatic activity against S. aureus. This low-cost, easy-to-operate strategy enables S. aureus detection and elimination, promising on-site use in food safety and clinical diagnosis.

Cannabis use is generally restricted worldwide because it contains the narcotic compound Δ9-tetrahydrocannabinol (Δ9-THC). Although cannabis is detected at crime scenes using color-based primary screening methods, the details of the reaction mechanism have not yet been elucidated. In this study, we isolated the products generated during the color reaction between the diazonium salt prepared from para-nitroaniline and nine cannabinoids and determined their structures. Azo compounds 6, 11, 16, and 17 were produced from cannabidiol, cannabigerol, cannabichromene, and cannabidiolic acid, respectively, while quinoneimines 7-10 and 12-15, which contained positional isomers, were produced from cannabinol, Δ9-THC, and hexahydrocannabinol. The reaction barely proceeded with Δ9-THC acetate and HHC acetate.

Silane-borate compound (10.0% borate) has proved to be termiticide. Four silane-borate compounds (10.0~13.8% borate) were prepared as termiticide, and then their stability under water rich environments were investigated. It was measured by the methods of the curcumic acid color reaction and the colorimetric with carminic acid. Results of these methods demonstrated the ability of the compounds to protect themselves against water attacks. This ability is performed by silane having groups with water repellency and reactivity to a wood surface, resulting that these silane-borate compounds have much better stability against water attacks compared to the standard termiticide DOT (15.0%) (Na2B8O13・4H2O).

Subclinical leaflet thrombosis is a major cause of failure in both surgical and transcatheter bioprosthetic heart valves. Thromboresistance is a basic prerequisite for a cardiovascular biomaterial. In this study, bovine pericardium (BP) was decellularized and processed (DCL-BP) with 0.2% glutaraldehyde (GA) and covalently conjugated with amino acid derivatives. Hexylamides of L-Glutamic acid (Glutamyl dihexylamide-GHA), L-Lysine (Lysinyl hexylamide─LHA), and the propargyl derivative of L-Lysine (Lysinyl propargyl amide─K1 alk) were investigated. These modifications of BP generate three different scaffolds (DCL-GHA BP, DCL-LHA BP, and DCL-K1 alk BP) of varying surface energies and hydrophilic/phobic properties. The surface modifications altered the water contact angles of glutaraldehyde-processed pericardium from 59.25° to 67.74° in DCL-GHA BP and 79.98° in DCL-LHA BP, while DCL-K1 alk BP became highly hydrophilic such that the measurement of static angle was not feasible. Successful conjugations were confirmed by quenching of acid fuchsin color reaction and confocal Raman chemical mapping. The materials were found to be non-hemolytic and greatly reduced the overall protein adsorption and platelet adhesion, thus markedly improving the surface thromboresistance in vitro as observed by the whole blood clotting assay. The results of the ex vivo study in the sheep model correlated well with the in vitro data, where a marked reduction in protein adsorption from whole blood and platelet adhesion/thrombus deposition was observed, in comparison with the thrombogenic control. There was no activation of coagulation or complement system by any of the three test materials, making them non-thromboinflammatory and suitable candidate materials for use as a bioprosthetic heart valve leaflet.

Brotowali stem (Tinospora crispa L.) is a plant that grows abundantly in Central Kalimantan and has been empirically used for generations as an antidiabetic remedy by the Dayak Ngaju community. Brotowali stem contains secondary metabolite compounds, including alkaloids, which possess various pharmacological activities, one of which is antidiabetic activity. This study aimed to determine the alkaloid content of Tinospora crispa stem extract in aquadest, ethyl acetate, and n-hexane fractions. The research employed an observational descriptive method by analyzing qualitative data through color reaction tests and quantitative data using UV-Vis spectrophotometry to determine alkaloid levels. The qualitative analysis results showed positive color reactions indicating the presence of alkaloid compounds. Quantitative analysis using UV-Vis spectrophotometry revealed that the total alkaloid content in the aquadest fraction was 20.19 mg or 20.19%, in the n-hexane fraction was 20.54 mg or 20.54%, and in the ethyl acetate fraction was 31.07 mg or 31.07%. The highest total alkaloid content was found in the ethyl acetate fraction. In conclusion, the extract of Tinospora crispa stem positively contains alkaloids, with the highest alkaloid content obtained in the ethyl acetate fraction at 31.07%.

The new species Cortinarius mapuveronicae from Andean-Patagonian Nothofagus-forests is described in a polythetic approach combining chemical analysis of the anthraquinonoid secondary metabolites, microscopical and morphological characteristics, as well as molecular phylogeny. C. mapuveronicae exhibits an intense red color reaction of the basidiomata by treatment with KOH, whereas the basidiospores are turning purplish brown. As responsible compound, the new anthraquinonoid pigment clavorubin-8-O-methylether (1), together with the known monomeric and dimeric anthraquinones (+)-7,7-emodinphyscion (2), emodin (3), emodin-6,8-di-O-methylether (4), questin (5), (+)-(S)-skyrin (6), (+)-(S)-aurantioskyrin (7), hypericin (8), dermolutein (9), and endocrocin (10) could be identified, showing also remarkable activity in a (photo)antimicrobial and (photo)cytotoxic assay. Phylogenetic analysis (ITS, LSU, rpb1) demonstrates a sister group relationship with the holotype of C. rubrobasalis.Graphical Supplementary InformationThe online version contains supplementary material available at 10.1007/s13659-025-00552-5.

In this work, an innovative microfluidic paper-based analytical device (μPAD) was developed for the quantification of zinc(II) in biological samples of non-invasive collection, namely children's urine. Zinc(II) in urine can be considered a biomarker of children's psychological development and mental conditions, as well as indicative of urinary tract diseases. The developed device is based on the colourimetric reaction between zinc and dithizone in an alkaline medium and is described as a simple, low-cost method with potential on-site applications. The colour reaction takes about 5min, and the resulting signal remains stable for 30min. It enables the quantification of zinc(II) within the dynamic range of 50.0-750μg/L, with a limit of detection (LOD) of 10μg/L and a limit of quantification (LOQ) of 34μg/L. After the device's assembly, it remains stable for use for up to one week when stored at room temperature, either in air or vacuum conditions. The method validation was performed by comparing the results obtained using the μPAD with those from atomic absorption spectrometry (AAS), where urine samples were analysed directly, or diluted (1:2) when necessary. The developed μPAD offers a user-friendly, portable, and cost-effective approach for the monitoring of zinc(II) levels in children's urine, providing point-of-care analysis in clinical diagnostics and public health monitoring.

Food safety is very important, especially when it comes to snacks that kids and adults eat a lot of. Rhodamine B is still often used as a food coloring, even though it has been banned because it can cause serious health problems, like liver damage and a higher risk of cancer from long-term exposure. This review seeks to investigate the occurrence of Rhodamine B in diverse food products available in the community and to evaluate the analytical methodologies employed in prior research. The research methodology employed is a literature review of national articles published between 2020 untill 2025, utilizing a literature search via Google Scholar with keywords pertinent to Rhodamine B and food analysis. Data were analyzed descriptively according to sample type and analytical methods, including color reaction tests, wool thread tests, thin layer chromatography (TLC), and UV-Vis spectrophotometry, along with the outcomes of Rhodamine B identification. The findings indicated that Rhodamine B was still present in various food items, particularly traditional red cakes, school snack crackers, unbranded jam, red velvet cakes, and certain steamed cakes. Layer cakes, jelly-based foods, cilok sauce, and shrimp paste, on the other hand, were said to not have Rhodamine B in them. This finding stresses the need for ongoing food monitoring and the use of good analytical methods.

Phenol color reaction has been used to distinguish between two subspecies of Asian rice (Oryza sativa), indica and japonica. The trait is controlled by one single Phr1 gene, which encodes a PPO enzyme that catalyzes the oxidation of phenolic compounds into brown or black pigments upon contact to phenol solution. In O. sativa, ssp. indica responds to phenol chemical assay by altering the rice hull color to black, whereas ssp. japonica remains unaffected due to mutations that render the gene non-functional. Although the different characteristics between subspecies in Asian rice is well known, there is no information about the variation of this trait in African rice, Oryza glaberrima, which was originated and domesticated independently of Asian rice. In this study, we found both phenol negative and positive lines in O. glaberrima and its wild ancestor O. barthii and detected the responsible non-functional mutation (1-bp deletion) in the exon 1 of the Phr1 gene. Geographical distribution of its haplotype suggested that this mutation originated in O. barthii in Mali and was later inherited by O. glaberrima. The predominance of the non-functional Phr1 alleles in O. glaberrima lines and the occurrence of the identical haplotypes in negative group of both O. barthii and O. glaberrima suggest that the negative phenol reaction was favored during domestication and breeding selection. The presence of a selection event is also supported by low nucleotide diversity of Phr1 locus. However, genetic diversity of Phr1 persists in African rice germplasm, as the functional alleles are still present in O. glaberrima. We also compared the nucleotide diversity of Phr1 in African rice with that in Asian rice and found that their origins of the phenol responsive phenotype are independent. These findings expand the current understanding of African rice domestication and offer the valuable molecular marker for improved rice breeding.

In the forensic examination of sexual assault cases, the Acid Phosphatase (AP) test is commonly used as a rapid presumptive screening method, while the PSA immunoassay is applied for confirmatory purposes due to its superior sensitivity. Immunochromatographic PSA (p30) tests are capable of detecting minute quantities of seminal material and often produce weak or trace positive results at dilutions where the AP test has already become negative. Because AP relies on an enzyme-based color reaction, its visible response diminishes at higher dilutions, limiting its practical detection threshold. PSA, a glycoprotein secreted by the epithelial cells of the prostate and present in high concentrations in seminal plasma, serves as a dependable biomarker for semen identification, particularly in cases where spermatozoa are absent due to azoospermia, vasectomy, or sample degradation. Comparative findings from both tests indicate that the PSA assay exhibits markedly higher sensitivity, detecting seminal fluid at greater dilutions (up to 1:2048 or more), whereas AP activity typically declines and becomes undetectable around 1:512–1:1024.Overall, while both AP and PSA tests are useful for identifying seminal stains, the PSA test offers a more sensitive and reliable means of detection at extreme dilutions where AP reactions become weak or inconclusive. Consequently, in rape investigations, PSA testing plays a critical role by enabling the sensitive detection of seminal fluid, reinforcing biological evidence, corroborating victim statements, facilitating DNA analysis, and providing robust scientific support within the criminal justice system and courts of law.

Succinimide additives play an important role in combating engine deposits and are therefore commonly blended in fuels. As many of the methods currently used to quantify them in fuel rely on time-consuming techniques and the use of expensive laboratory equipment, a more practical approach was explored. For this purpose, an existing method for aqueous samples involving a colour reaction with Rose Bengal dye and spectrophotometric detection in the UV/Vis range was modified for usage in the nonpolar fuel matrix and tested for applicability. The result was an accessible method for determining the succinimide additive content of diesel fuel—including biodiesel—that is easy to implement in the laboratory routine.

Acute myocardial infarction (AMI) poses a severe threat to human health, making its rapid and sensitive diagnosis crucial. Cardiac troponin I (cTnI) has been established as the gold standard biomarker for AMI diagnosis. Herein, a dual-mode immunosensor was constructed by integrating manganese dioxide (MnO2) nanozyme and fluorescence carbon dot (B-CDs) in silica (SiO2), termed B-CDs@SiO2@MnO2, for the colorimetric and fluorescent detection of cTnI. The sensing signal mainly included two parts: B-CDs@SiO2@MnO2-based catalytic color reaction and B-CDs@SiO2 fluorescence recovery after etching MnO2. The MnO2 nanozyme catalyzes the oxidation of TMB to generate blue-colored TMBox, which turns yellow upon acid addition, enabling colorimetric detection. Concurrently, the MnO2 nanosheets quench the fluorescence of B-CDs@SiO2. In the presence of ascorbic acid (AA), MnO2 is reduced to Mn2+, leading to fluorescence recovery and thus enabling fluorescent detection. Profiting from the superior self-correction features of B-CDs@SiO2@MnO2 dual-mode sensor, this method exhibits good linearity and sensitivity toward cTnI among 0.05-50 ng/mL, with detection limits of 0.0074 ng/mL for the colorimetric mode and 0.0063 ng/mL for the fluorescent mode. In addition, the human serum samples' recoveries show good agreement between the colorimetric mode (90.0-117.8%) and the fluorescent mode (90.2-115.8%). Furthermore, we employ this platform to monitor cTnI levels in both cellular and blood samples from AMI patients, indicating the promising clinical application potential of this platform.

Bright skin is frequently considered the main beauty indicator in Indonesia. This belief drives many women, and maybe men, to strive for any strategies to make their skin brighter or become white instantly. Cosmetics business owners are no exception, even if several people have deliberately included prohibited ingredients to gain more profit. Mercury and hydroquinone are the two most prohibited ingredients often found in whitening cream. This study aims to analyze mercury and hydroquinone and mercury levels in body whitening creams sold in cosmetic stores and marketplaces in Malang City, Indonesia. Mercury was detected qualitatively using KI 0.5 N, NaOH 2 N, and HCl 2 M color reagents, respectively, while the mercury levels were quantified using a mercury analyzer. On the other side, hydroquinone was detected qualitatively by the FeCl3 color reagent and KLT method, along with the High-Performance Liquid Chromatography (HPLC) method for quantitative measurement. The validation of method analysis of hydroquinone has fulfilled the parameters, including specificity and selectivity (retention time 2.111 ± 0.004 min; resolution 4.556 ± 0.096; tailing factor 1.446±0.1909), linearity (y = 44563x - 54717; r = 0.999), accuracy (%recovery = 97.9-102.8%), precision (%RSD = 0.38-0.94%), LOD (1.695 ppm) and LOQ (5.137 ppm). Based on the qualitative and quantitative analysis methods, it can be concluded that all samples contained mercury less than &amp;lt; 1 mg/kg, but only one sample has been proven to contain 4.35 ± 0.24% hydroquinone.

In this study, a novel fluorescent "turn-on" probe, (E)-N'-(2-(2-hydroxynaphthalen-1-yl) ethylidene)-2,5-diphenyl-2H-1,2,3-triazole-4-carbohydrazide (G4), was designed and synthesized, and fully characterized by various analytical techniques. Spectroscopic investigations revealed that G4 exhibits excellent selectivity and sensitivity toward Al3+, with a 1:1 binding stoichiometry and a detection limit of 1.623 nM. Its advantages over existing probes include the lower detection limit and a distinct color reaction under UV light, which facilitates straightforward qualitative detection with lower cytotoxicity. The sensing mechanism was elucidated through density functional theory (DFT) and quantum chemical calculations. Then the practical utility of G4 was demonstrated through recovery experiments in real water samples and its development into a portable test kit. Furthermore, cell experiments and zebrafish imaging confirmed its biocompatibility and applicability in biological systems with lower cytotoxicity. As a candidate drug that may be developed and utilized, the interactions of G4 with two serum proteins (HSA and HIgG) were also investigated through spectrofluorometric and molecular docking analysis, revealing hydrogen bond or van der Waals forces as the main mode of action, suggesting potential for further biomedical applications. These results highlight G4 as a highly sensitive, selective, and dual-functional fluorescent probe with significant potential for environmental monitoring and biological sensing.

The exploitation of an extremely sensitive and reliable nanozyme based colorimetric sensor for highly sensitive detection of hydrogen peroxide (H2O2) in living body system is extensively carping owing to fact that it garnered a prime role in causing toxic diseases. In this work, a highly novel catalyst named as Cerium oxide (CeO2) nanosheets (NSs) was precisely prepared by using a simple one pot hydrothermal method, thereby dowered with a strong intrinsic peroxidase like capability of catalyzing the oxidation-reaction of colorless 3,3',5,5'-tetramethylbenzidine (TMB) to generate a blue color reaction in the presence of H2O2. Hence, a sensitive visible assessment platform related to CeO2 NSs was engineered, which not only exhibited a wider detection range of 0.01-1000 µM with R2 value of 0.9998, but also perceives exceptional selectivity, tremendous cycling and long term stability. Further, the sensor also evaluates lowest detection limit (LOD) 0.29 ± 0.03 µM and quantification limit (LOQ) of 2.3 ± 0.03 µM. In addition, it also endorses impressive practicality with stronger sensitivity and favorable accuracy in serum samples. Thus, this research-work not only contributed upon CeO2 NSs an outstanding capacity to detect H2O2, but also expands the realm of applications for CeO2 NSs in the domains of environmental preservation, biomedical diagnosis and forensic sciences.