Colorimetric Performance Research Articles

Minimizing the cobalt content in black ceramic pigments by Design of Experiments

This paper presents a comprehensive optimization strategy for the synthesis of new black ceramic pigments with low cobalt content while maintaining a single-phase spinel structure. The aim is to achieve comparable hues to those of an industrial benchmark containing five transition metals while minimizing the environmental impact. Exploring all possible compositions deriving from a five–component system (Cr, Mn, Fe, Co and Ni), through traditional methods would be extremely time consuming to guarantee an efficient sampling, requiring high experimental efforts. Hence, to identify the best black compositions, we employed a chemometric approach, the Design of Experiments, aiming to investigate the compositional domain derived by varying the metals stoichiometry within fixed boundaries to identify optimal pigment compositions. The resulting pigments (comprising Cr, Fe and Co), despite the lower cobalt content, exhibited optimal colorimetric properties comparable to the standard benchmark, with experimental ΔE values comparable to the ones predicted by the model. In particular, the pure spinels Cr1.05Fe1.05Co0.9O4 and Cr1.2Fe1.05Co0.75O4 displayed low lightness and chroma (L∗ = 2.4; C∗ = 5 and L∗ = 1.12; C∗ = 1.1, respectively), providing deep and dark black tonality. These compositions exhibit promising colorimetric performance and chemical stability, offering potential benefits for industrial applications.

A cocatalytic nanozyme based on metal-organic framework-embedded iron porphyrin for the sensitive detection of Salmonella typhimurium in milk

The nanozyme, acting as the signal labeling reporter, is widely employed in colorimetric immunoassays due to its exceptional catalytic activity and reliable performance. Nonetheless, when immobilized on the nanozyme's surface, there is a decline in catalytic activity, which hinders its ability to meet the escalating demand for advanced colorimetric immunoassays. Herein, we introduce a novel MILL-88@TcP nanozyme, formed by encapsulating iron porphyrins (TcP) within metal-organic frameworks (MILL-88), where the catalytic activity of TcP is fully preserved through ethanol-induced release. Leveraging the superior encapsulation capacity and enzyme-mimicking characteristics of MILL-88, the MILL-88@TcP nanozyme demonstrates a remarkable colorimetric performance, 1430-fold higher than that of MILL-88 alone. Furthermore, we developed the MILL-88@TcP nanozyme-based Enzyme-Linked Immunosorbent Assay (N-ELISA) for enhanced sensitivity in detecting Salmonella typhimurium, achieving a detection limit of 1.68 × 102 CFU/mL, approximately 500-fold enhancement compared to the traditional HRP-based ELISA (8.35 × 104 CFU/mL). Notably, the average recoveries ranged from 91.50 % to 108.50 % with a variation of 3.53 %–10.41 %, indicating high accuracy and precision. Collectively, this study highlights that the MILL-88@TcP nanozyme, with its superior catalytic performance and anti-interference capabilities, holds promise as a colorimetric labeling reporter to enhance the detection efficacy of colorimetric immunoassays and has the potential to establish a more stable and sensitive colorimetric assay platform.

Method for controlling the polypropylene wettability using surfactants

This paper describes a novel approach to imaging polypropylene PP using digital inkjet printing techniques. The low surface energy of PP, and significant hydrophobic properties prevent it from being used for direct coloration by available methods. A number of surfactants (surfactants) have been proposed as pre-coatings to improve the adhesion between the polymer surface and the ink. Due to the amphiphilicity of surfactants, improved coloration and enhanced color rendering are provided. The polymer/surfactants interactions were evaluated by IR spectroscopy. The amount of surfactants was evaluated using TGA analysis. The effect of modifying agent concentration was evaluated using wetting edge angle measurement. The surface morphology was evaluated using scanning electron microscopy. The test scales were printed and their colorimetric performance was investigated. The study demonstrates the high potential of surfactants for tuning the properties of nonwoven polymeric materials.

Evaluation of photoluminescence and colorimetric performance of Tb3+-induced calcium tungstate ceramic

Evaluation of photoluminescence and colorimetric performance of Tb3+-induced calcium tungstate ceramic

Starch‐based nanoparticles as a replacement for synthetic latex: A comprehensive assessment of printability and colorimetric characteristics

AbstractThe papermaking, packaging, and printing industry are actively seeking sustainable material alternatives to address growing concerns about environmental consciousness and finite resources. Synthetic latex, a frequently utilized binder in paper coating formulations, present difficulties due to their dependence on fossil fuel resources and their reduced recyclability in comparison to eco‐friendly sustainable products. In this study, synthetic latex was replaced with a starch‐based nanoparticle (starch NP) binder at a 1:1 ratio in a coating formulation. Printing trials to assess colorimetric characteristics was made using electrophotography (EP) printing, given the current upward trajectory and expansion of EP technology into the label, packaging, and folding carton sectors. The in‐depth investigations reveal that incorporating starch NP binder result in improved optical, color, and dot characteristics. Moreover, it maintains consistent and comparable coefficients of friction. Partial replacement of synthetic latex with the starch NP binder yields significant enhancements in surface roughness and text quality. Importantly, the starch NP binder not only improves the dielectric relaxation properties of the paper and enhances toner transfer but also accelerates the distribution of the electrical field compared to synthetic latex, optimizing toner transfer and thereby enhancing color gamut volume. The study demonstrates that employing the starch NP binder leads to substantial improvements in colorimetric performance without any drawbacks in EP printing, making it highly advantageous to replace 50% of the synthetic binder.

Enzymatically green-produced bacterial cellulose nanoparticle-stabilized Pickering emulsion for enhancing anthocyanin colorimetric performance of versatile films

To enhance the colorimetric performance of anthocyanin (Ant), a konjac glucomannan (KGM)-based multifunctional pH-responsive indicator film was fabricated by introducing enzymatically prepared bacterial nanocellulose (EBNC) stabilized camellia oil/camellia essential oil Pickering emulsion (BCCE). Specifically, optimized enzymatic hydrolysis time (36 h) was determined based on the particle size and microstructure. Then BCCE (containing 0.4% EBNC) was incorporated into Ant-containing KGM, and the novel active indicator film (KGM-Ant-BCCE) was constructed. Films with varying BCCE concentrations (3%–11%) exhibited enhanced UV shielding, thermal stability, mechanical strength, water vapor and oxygen permeability, hydrophobicity, and antioxidant performance. The pronounced color change of KGM-Ant-BCCE indicated its potential for visually detecting shrimp freshness. Moreover, the biodegradability (25 days) confirmed the environmentally benign property of the film. In summary, incorporating green-produced EBNC nanoparticle-stabilized BCCE offers an innovative pathway to improve the color indication capability of polysaccharide-based smart packaging.

Analysis of Structural, Photoluminescence, and Colorimetric Performance of Gd-Incorporated BNT Ceramic.

Structural, optical, photoluminescence and colorimetric analyses of Gd (1-5mol %) doped BNT ceramics synthesized by the solid-state reaction technique are reported. Structural analyses of all the samples are done by the X-ray diffraction method. It is shown that the samples have rhombohedral crystal structures with an R3C space group. The energy band gap of all the phosphors is computed from the UV-visible absorbance spectra. Photoluminescence behaviors are analyzed from the excitation along with the emission spectra of the prepared materials. The critical quenching concentration with the critical energy transfer distance is observed owing to the dipole-dipole interactions between the materials. Colorimetric analyses are carried out with the help of CIE chromaticity. Moreover, the color purity, correlated color temperature, color rendering index, and luminous efficiency of radiation values are evaluated by using the chromaticity coordinates.

Dual-mode biosensors for ultrasensitive detection of Legionella pneumophila using CRISPR/Cas12a integrated recombinase polymerase amplification

Legionella pneumophila (L. pneumophila) can cause respiratory disease in humans when it infects water sources, posing a major challenge to public health and the environment. Herein, we further explore the potential application of CRISPR/Cas12a and develop CRISPR/Cas12a-drived fluorescent and colorimetry dual-mode biosensors for detection L. pneumophila. In this design, Amplified part not only realizes fast and convenient operation, but also avoids aerosol pollution. Bi2Fe4O9 NSs have excellent colorimetric performance and Bi2Fe4O9 NSs-coated DNA hydrogel can serve as independent unit. Experimental results demonstrate that the limit of detection (LOD) for the fluorescent biosensor is 7.606 × 10−6 ng/μL (3.8 copies/μL) with 60 min, which is 10,000 times better than the industry standard (SN/T 2528 - 2010). While the colorimetry achieves a LOD is 7.606 × 10−3 ng/μL (3800 copies/μL) with 100 min, which is 10 times better than the industry standard. In the actual sample test, the selectivity of the detection scheme is 100%, and the positive detection rate is higher than the industry standard 10.71%. We take the lead in integrating RPA and CRISPR/Cas12a for detecting L. pneumophila, which has been further broadened the detection strategy by incorporating colorimetric sensing. Moreover, this biosensor demonstrates excellent repeatability and strong universality, along with practical applicability for various water environment monitoring purposes.

Predicting the Colorimetric Performance of White LEDs Based on Gaussian Spectral Parameters

Predicting the Colorimetric Performance of White LEDs Based on Gaussian Spectral Parameters

Luminescence studies of high color purity red-emitting [formula omitted] phosphor prepared by microwave-assisted synthesis technique

A set of red-emitting phosphor materials (Ca1−xAl4O7:Eux3+, x = 0, 0.01, 0.03, 0.05, 0.07, 0.09, 0.11, 0.13) were synthesized through microwave-assisted combustion synthesis for the first time. The crystal structures and phase purity of Eu3+ ions-activated calcium dialuminate (CaAl4O7) phosphor were investigated by XRD study and Rietveld refinement analysis were performed. The prepared phosphors exhibit monoclinic crystal structure having C2/c space group. From the radius difference percentage calculation, the occupancy of Eu3+ ions in Ca2+ sites was confirmed which is in better harmony with the refinement result. Morphological analysis was investigated through SEM study. Structural characteristics and the presence of the functional groups were analysed though FTIR study. The optical band gap (Eg) was determined to be 5.46 eV by studying the UV–VIS reflectance spectra. PL measurements were carried out for the prepared material to study the luminescent behaviour. The presence of charge transfer band was observed in the excitation spectra. It is found that the prepared phosphor materials exhibits emission rich in red at 611 nm with fixed excitation wavelength at 393 nm. The concentration quenching and energy transfer kinetics were analysed by employing Blasse and Dexter’s formula that attributed the non-radiative energy transfer to the dipole-dipole (d-d) interactions. Local site symmetry was analysed to study the symmetry of the environment in the neighbourhood of Eu3+ ions in the host matrix. To analyse the colorimetric performance of the phosphor materials, the correlated color temperature (CCT), color purity were calculated by using the CIE chromaticity co-ordinates (CIE 1931). The calculated CCT value shows the appearance of the emitted color of the phosphor in the warmer region. CaAl4O7:Eu3+ phosphor manifests high color purity which was found to be 97.39 %. The PL decay time measurement were performed for Ca1−xAl4O7:Eux3+ (x = 0.07) phosphor to obtain the decay lifetime. The estimated decay time (1.44 ms) indicates that the prepared phosphor material has a good potency to be utilized as a red-emitting phosphor for wLED, display technology and other applications.

Systematic comparison of head mounted display colorimetric performance using various color characterization models

The advancement of virtual reality in recent times has seen unprecedented applications in the scientific sphere. This work focuses on the colorimetric characterization of head mounted displays for psychophysical experiments for the study of color perception. Using a head mounted display to present stimuli to observers requires a full characterization of the display to ensure that the correct color is presented. In this paper, a simulation is done to mimic a practical display with color channel interactions and characterization of simulated data is done using the following models: gain offset gamma model, gain offset gamma offset model, gain gamma offset model, piecewise linear assuming chromaticity constancy model, piecewise linear model assuming variation in chromaticity, look-up table model, polynomial regression model, and an artificial neural network model. an analysis showed that the polynomial regression, artificial neural network, and look-up table models were substantially better than other models in predicting a set of rgb values, which can be passed as input to a head mounted display to output desired target xyz values. both the look-up table and polynomial regression models could achieve a just noticeable difference between the actual input and predicted output color of less than 1. the gain offset gamma, gain offset gamma offset, and gain gamma offset models were not effective in colorimetric characterization, performing badly for simulations as they do not incorporate color channel interactions. the gain offset gamma model was the best among these three models and the lowest just noticeable difference it could achieve was over 13, clearly too high for color science experiments.

Nanocatalyst-triggered cascade immunoassay: Multi-model immunochromatography assay for sensitive detection of Salmonella typhimurium

The Salmonella-caused food safety problem is a potentially serious threat to public health and economic development, which stresses an urgent need for effective strategies to control the spread of food-borne pathogenic bacteria. In this work, a nanocatalyst-triggered cascade immunoassay (NTCI) combined with colorimetric-catalytic-photothermal multi-model signals has been developed for the detection of Salmonella typhimurium (S. Typhimurium). PtNiCo@TA trimetallic nanoflower was employed as the signal label of the NTCI, due to its excellent peroxidase-mimicking properties, colorimetric performance, biocompatibility, and stability. Here, the multi-model NTCI consists of three parts: (i) colorimetric immunochromatography assay (ICA) with a double antibody sandwich system, (ii) catalytic amplification system triggered by 3, 3′, 5, 5′ -tetramethylbenzidine (TMB) and hydrogen peroxide (H2O2), and (iii) photothermal analysis achieved by the near-infrared (NIR) laser-driven photothermal properties of oxidized TMB (oxTMB). Based on this multi-model cascade reaction, both specific qualitative and quantitative analyses of pathogenic bacteria are realized. The limit of detection (LOD) of multi-model NTCI is 500 cfu·mL−1, which is 20-fold more sensitive than that of the colorimetric analysis alone. Moreover, the NTCI system shows preeminent applicability and flexibility for S. Typhimurium detection in milk samples. Therefore, this work suggests an innovative direction for the design of nanocatalyst-triggered photothermal multi-model immunoassays in the detection of food-borne pathogens.

Downconverted significant luminescence enhancement and structural confinement of a dichromatic nanophosphor for potential applications in NUV-triggered cool pc-WLEDs

Trivalent rare-earth ions activated phosphor-converted near ultraviolet (NUV) triggered white light-emitting diodes (WLEDs) are nowadays being explored as a prominent light source, in the field of lighting. Herein, we prepared a sequence of single-phase Gd2O3:Dy3+,Li+nanophosphor via chemical co-precipitation techniques for the applications in cool pc-WLEDs. To examine the crystal structure, luminescent characteristics, and potential applications of WLEDs, a systematic and comprehensive analysis was conducted. This study extensively investigated the effect of Li+ on the Gd2O3:Dy3+white-emitting nanophosphor. The phase purity and crystal structure of nanophosphors were characterized via powder X-ray diffraction (XRD) analysis. Rietveld refinement clearly quantified that the Gd2O3 host possesses two non-equivalent cationic sites that are coordinated sixfold. The interior morphology and elemental composition were illustrated by high-resolution transmission electron microscopy (HR-TEM) and energy dispersive spectroscopy (EDS). These nanophosphors effectively exhibit dichromatic significant photoluminescence (PL) emission bands of Dy3+ ion for blue and yellow color at 486 and 574 nm, while triggered in the NUV range. The blending of blue and yellow color lights yields a broad spectrum of light that appears white color to the human eye. Besides, it has been observed that the incorporation of Li+ significantly enhances the PL-emission intensity. The critical distance between Gd3+ and Dy3+ was determined, and it showed that the electric multipolar interaction was responsible for the energy transfer quenching mechanism. The colorimetric performance reveals that the CIE coordinates fall within the white region of the color space and that the correlated color temperature (CCT) is substantially higher than 4000 K. The lowest color purity (CP) was found to be 4.0% for x = 2 at.%Li+ ion concentration under excitation wavelength 350 nm. These findings suggest that the prepared nanophosphors are a suitable candidate for application in NUV-triggered cool-WLEDs.

Performance-enhanced regenerated cellulose film by adding grape seed extract

Eco-friendly packaging material with intelligent colorimetric performance has been a requirement for food safety and quality. This work focused on a food packaging material from regenerated cellulose films that added the grape seed extract (GSE) and polyethylene glycol 200 (PEG). FTIR and SEM techniques were employed to prove the compatibility of GSE with cellulose matrix. The composite film showed an enhanced elongation at break (16.61 %) and tensile strength (33.09 MPa). The addition of PEG and GSE also improved the water contact angle of regenerated-cellulose film from 53.8° to 83.8°. Moreover, the composite films exhibited UV-blocking properties while maintaining adequate transparency. The GSE induced the regenerated films with a macroscopic change in color under different pH conditions. Furthermore, the loading of GSE slowed down the decomposition of strawberries and delayed the self-biodegradation compared with the control for more than 3 days and 18 days. The present study showed a regenerated cellulose film with acceptable mechanical and hydrophilia properties, pH-responsiveness, anti-decomposition, and delayed biodegradation performances, indicating a potential color sensor in food packaging.

Joint-detection of Salmonella typhimurium and Escherichia coli O157:H7 by an immersible amplification dip-stick immunoassay

To explore the superiority of multifunctional nanocomposites and realize the joint-detection of foodborne pathogens, an immersible amplification dip-stick immunoassay (DSIA) was exploited for the sensitive detection of Salmonella typhimurium (S. typhi) and Escherichia coli O157:H7 (E. coli O157:H7). Saving for the basic colorimetric performance, the reporter molecule of CoFe2O4 (CFO) possesses multivalent elements (Co2+/3+, Fe2+/3+) as well as multifunction of superior catalase-like activity and magnetic properties. By dint of the catalytic activity of CFO, a directly immersible amplification can be simply achieved to endure the DSIA with an intensive signal and a dual-visible mode for the determination of S. typhi and E. coli O157:H7. In virtue of the magnetic separation and enrichment capability of the CFO, the DSIA can perform a matrix-interference-free detection and obtain a dynamic detection range of 102–108 CFU/mL and a low assay limit of 102 CFU/mL. Moreover, the DSIA has reasonable recovery rates for contamination monitoring of two target bacteria in milk and beef samples. Our research provides a persuasive supplement for the application of multifunctional nanocomposites in the ongoing dip-stick immunoassay and an alternative strategy for the efficient detection of foodborne pathogens.

Anthocyanins of Açaí Applied as a Colorimetric Indicator of Milk Spoilage: A Study Using Agar-Agar and Cellulose Acetate as Solid Support to Be Applied in Packaging

Food that is still fit for consumption is wasted in the domestic environment every day, so food packaging technologies are being developed that will monitor the quality of the products in real time. Highly perishable milk is currently one of the products that suffers most from this waste, due to its short shelf life. Active use-by date (AUBD) indicators have been shown to discriminate between fresh and spoiled milk. Colorimetric indicators undergo characteristic changes in their chemical structure, causing abrupt color changes. Among the polymeric materials studied that may function as solid support are cellulose acetate (CA) and agar-agar (AA). The AA colorimetric indicator proved to be more suitable as a solid support due to its ability to maintain the color change properties of the anthocyanin and its high colorimetric performance. The technique was shown to be capable of indicating, in real time, changes in milk quality.

A dual-channel visual sensing system for recognition of multiple metal ions

Here, we propose a simple, rapid, and effective colorimetric sensor array for discrimination of metal ions. The sensor array was constructed using two sensing channels, i.e., gold nanoparticles (AuNPs)- Tetramethylbenzidine (TMB)-H2O2 and AuNPs-O-phenylenediamine (OPD)-H2O2 reaction systems. The presence of metal ions with positive charges would lead to the corresponding surface charge change of negatively charged AuNPs, resulting in diverse catalytic performances of citrate-modified AuNPs, accompanied by a substantial colorimetric performance of oxidation products of TMB and OPD. Employing the diversity of colorimetric responses of metal ions to the two sensing channels, nine metal ions including Cr3+, Fe3+, Cu2+, Co2+, Ni2+, Pb2+, Mg2+, K+, and Cd2+ were well distinguished with a discrimination accuracy of 100% at a concentration as low as 50 nM. Further experiment showed that the sensor array was also capable of discriminating and quantifying metal ions at various concentrations, as well as the identification of metal ion mixtures. The feasibility of the sensor array was also verified by the successful identification of the nine metal ions in river water samples.

Improvement strategies on colorimetric performance and practical applications of Paper-based analytical devices

Colorimetric paper-based analytical devices (PADs) have been widely fabricated due to the ease of construction of colorimetric reactions on paper and the high compatibility with low-cost and easy-to-use imaging devices for on-site analysis and results recording. However, the further advance of colorimetric PADs is limited by the detection sensitivity and other intrinsic limitations of paper regarding the color quality. This review summarizes the strategies for improving the colorimetric performances (color intensity and uniformity) of PADs. In particular, the principles of controlling liquid-paper interaction for the color intensity enhancement, developed in printing research, are discussed in relation to PAD designs. The influence of the paper assaying environment to the paper assaying selectivity is discussed through a case study for the first time. Image capture techniques and image process algorithms are related to the accuracy and sensitivity of the colored results, which are carefully introduced. Finally, based on the tendency of improvement of colorimetric PADs for practical applications, we summarized the designs that enhance the portability of colorimetric PADs. It is believed that the new links and opinions provided in this review may be useful to researchers to address the challenges in designing future colorimetric PADs with improved sensitivities for field use.

A simple sulfonohydrazide Schiff base molecular probe for colorimetrically selective recognition of Cu2+ ion in Semi-Aqueous medium

A novel sulfonohydrazide Schiff base colorimetric probe 4-methylbenzenesulfonohydrazide (R1) has been designed and synthesized which shows sensing recognition of Cu2+ in CH3CN:H2O (7:3, v/v) semi-aqueous medium. The prepared probe R1 was characterized using spectroscopic methods, including FT-IR, 1H NMR, and HRMS spectrometry. R1 exhibits an excellent selectivity to Cu2+ over other examined metal ions with a prominent colorimetric performance from colorless (345 nm) to crimson yellow (420 nm) under daylight. UV–vis titration experiment in the presence of different molar fractions of Cu2+ was used to perform a Job’s plot analysis. The results showed that the stoichiometric ratio of the complex formed by R1 and Cu2+ was 2:1. A paper strip pre-stained with R1 solution was further fabricated and it also showed excellent sensing ability toward Cu2+ with a detection limit as low as 2.74 × 10-7 M with the naked eye, which represents better portability and operation simplicity that is favourable for on-site analysis of Cu2+ in water. The sensing mechanism was further verified with HOMO–LUMO energy levels were calculated using experimental and theoretical studies (DFT/TD-DFT), which correlated with good agreement.

Evaluation of the colour quality of display primary: Part I. Chromaticity based methods.

It is a challenge to determine the RGB primaries when designing a display. A big issue is to estimate the colorimetric performance of the display. In this paper, a systematic method was proposed to determine the best RGB primaries for a display. Nine testing metrics were implemented and they were divided into two groups (the gamut metrics and the colour related metrics). They were adopted to evaluate the performance of 52 displays having different RGB primary combinations. The results verified the proposed method. Some of the testing metrics gave similar results and it should be sufficient to choose some of them to reveal the overall performance of a display.