Artificial intelligence-assisted colorimetry for urine glucose detection towards enhanced sensitivity,accuracy,resolution,and anti-illuminating capability

Colorimetry often suffers from deficiency in quantitative determination,susceptibility to ambient illuminance,and low sensitivity and visual resolution to tiny color changes.To offset these deficiencies,we incorporate deep machine learning into colorimetry by introducing a convolutional neural network(CNN)with powerful parallel processing,self-organization,and self-learning capabilities.As a proof of concept,a plasmonic nanosensor is proposed for the colorimetric detection of glucose by coupling Benedict’s reagent with gold nanoparticles(AuNPs),which relies on the assemble of AuNPs into dendritic nanochains by Cu2O.The distinct difference of refractive index between Cu2O and Au and the localized surface plasmon resonance coupling effect among AuNPs leads to a broad spectral shift as well as abundant color changes,thereby providing sufficient data for selflearning enabled by machine learning.The CNN is then used to fully diversify the learning and training of the images from standard samples under different ambient conditions and to obtain a classifier that can not only recognize tiny color changes that are imperceptible to human eyes,but also exhibit high accuracy and excellent anti-environmental interference capability.This classifier is then compiled as an application(APP)and implanted into a smartphone with Android environment.306 clinical urine samples were detected using the proposed method and the results showed a satisfactory correlation(87.6%)with that of a standard blood glucose test method.More importantly,this method can be generalized to other applications in colorimetry,and more broadly,in other scientific domains that involve image analysis and quantification.

Research Progress in Detection of Explosives by Chemical Colorimetric Method

This article reviews the current application status and research progress of colorimetric detection methods based on chemical colorimetry in the detection of explosives.It mainly introduced colorimetric sensors,colorimetric sensor arrays,and chemical colorimetric sensors based on novel material substrates.The application prospect of chemical colorimetric method in the field of explosives detection was prospected.

Quantifying Hypochlorous Acid Concentration in Environmental Water Using Smartphone Colorimetry

In this study,we developed an eff ective method to detect hypochlorite acid(HClO)by using methylene blue(MB)derivative(BPY1).BPY1 was selectively oxidized through HClO,and the solution color changed from colorless to blue.In the presence of HClO,the ultraviolet–visible(UV–vis)spectra and concentration of HClO had a linear relationship with a detection limit of 0.5μM.Furthermore,a test paper for HClO monitoring was successfully prepared using the BPY1 probe,and the observed detection limit by the naked eye was estimated at 5μM.Additionally,using the BPY1 probe,HClO could also be detected through smartphone colorimetry,and the method showed a good recovery ranging from 98.7 to 104.0%for HClO detection in an actual water sample.Especially for developing countries,such a low-cost and highly sensitive detection method provides a simple and practical method for monitoring HClO in water.

Study on Tri-Stimulus Transformation

To decrease number of samples for the implementation of color space transformation, a method for modeling the chromatic characterization of video cameras was proposed. An additional transformation was required to predict output RGB values for an input color. This additional transformation was based on spectral reflectance relationship. The transformed color coordinates were taken as inputs of a multilayer neural network. Based on network outputs, the RGB values to be predicted were calculated. Experimental results were given to illustrate the performance of the method. Even though much less number of training samples are used, this method can also perform well on this color space transformation.

Antioxidant power of phytochemicals from Psidium guajava leaf

Dried ground leaves of Psidium guajava L. (guava) were extracted by water and aqueous ethyl alcohol 50% (1:10) ratio, and the total phenolic content in the extracts was determined spectrophotometrically according to Folin- Ciocalteu’s phenol method and calculated as gallic acid equivalent (GAE). Remarkably high total phenolic content 575.3 ±15.5 and 511.6±6.2 mg of GAE/g of dried weight material (for ethanol guava leaf extracts and water guava leaf extracts, respectively) were obtained. The antioxidant activity of lyophilized extracts was determined at ambient temperature by means of a 2,2-diphenyl-1-picrylhydryzyl (DPPH˙) colorimetry with detection scheme at 515 nm. The activity was evalu- ated by the decrease in absorbance as the result of DPPH˙ color change from purple to yellow. The higher the sample concentration used, the stronger was the free radical-scavenging effect. The results obtained showed that ascorbic acid was a substantially more powerful antioxidant than the extracts from guava leaf. On the other hand, the commercial guava leaf extracts and ethanol guava leaf extracts showed almost the same antioxidant power whereas water guava leaf extracts showed lower antioxidant activity. The parameter EC50 and the time needed to reach the steady state to EC50 concentration ( TEC50 ) affected the antiradical capacity of the sample. The antioxidant efficiency (AE) has been shown to be a more ade- quate parameter for selecting antioxidants than the widely used EC50. This study revealed that guava leaf extracts comprise effective potential source of natural antioxidants.

Prevalence of sensitive skin and its biophysical response in a Mexican population

AIM: To describe the frequency and biophysical response of sensitive skin in Mexican subjects, using the lactic acid test.METHODS: The lactic acid stinging test was applied to 250 healthy volunteers, both sexes, 18 years of age or older, without any active dermatoses on the test site. Volunteers were university students, workers of public institutions, and general population from San Luis Potosi, Mexico. Participants were not excluded based on socioeconomic status. Demographic data were obtained through a questionnaire. Skin phototype was obtained through colorimetry. Subjects were randomized to receive 10% lactic acid on one nasolabial fold and placebo on the other side. The presence and intensity of adverse sensations, such as itching, burning, or stinging, was evaluated through a 10-point VisualAnalogue Scale(VAS) prior to treatment and at 3, 5, 8 and 10 min after the intervention. Subjects with a VAS of 2 or higher were considered positive for the test. A VAS lower than 2 was considered a normal response to skin manipulation. Simultaneously, biophysical changes and barrier function were assessed by colorimetry, transepidermal water loss(TEWL), and capacitance. To decrease measurement variations by skin manipulation, the nasolabial fold was segmented in four areas of 1 cm2 for each time measurement. Descriptive analyses were made using central tendency measures. Analyses of data were performed using two-tailed c2 test, Fisher's test, t-test, logistic regression, or Mann-Whitney U test for non-parametric values between groups. RESULTS: Of the included 246 subjects, 68% were women and the mean age was 32 years. The most frequent skin phototype was Ⅴ(ranges Ⅱ-Ⅴ). Thirty-six percent of the subjects identified themselves as having sensitive skin. Fifty-two percent of the subjects were positive to the lactic acid stinging test, with a mean VAS of 4.5 at 3 min. Subjects with the self-diagnosis of sensitive skin were more likely to be positive for the test(80% vs 36%, P < 0.001). Lighter skin phototypes(types Ⅱ and Ⅲ) showed a higher response to the test compared to darker skin tones(type Ⅴ; OR = 0.88, P < 0.001). There were no statistical differences in baseline biophysical measurements. At 3 min, TEWL was significantly higher in subjects positive to the test(27.5 vs 23.7, P < 0.05). At 5 min, TEWL and capacitance showed statistical differences(26.0 vs 22.4, P < 0.05, and 239 vs 179, P < 0.05, respectively). After 5 min, values tended to return to baseline levels in both groups.CONCLUSION: Sensitive skin is frequent in our population. Darker skin phototypes have a lower prevalence of this syndrome, probably due to inherent differences in skin barrier function.

Features of Color Characteristics of Blood Plasma of Patients with Liver Cirrhosis in the Colorimetric System XYZ as Compared with Healthy People

The authors determined a connection between change of functional state of human with liver cirrhosis and color characteristics of blood plasma. Features of color characteristics of blood plasma of patients with liver cirrhosis as compared with those of healthy people were determined by colorimetric method, based on absorption electromagnetic radiation in visible area. The average chromaticity coordinates in the XYZ system for patients with liver cirrhosis are x = 0.352 ± 0.006, y = 0.356 ± 0.005 as compared with healthy people chromaticity coordinates x = 0.32 ± 0.001, y = 0.32 ± 0.002.

A smartphone-based calibration-free portable urinalysis device

As one of the most common medical diagnosis methods, urinalysis is a highly demanded technique for screening tests or daily monitoring of various diseases. With the rapid development of POC(point-of-care) systems, a convenient house-using urinalysis device is widely needed. However, considering the difference of onboard systems and multiple test indicators in urinalysis, the design of such an intelligent device is still challenging. In this paper, a smartphone-based portable urinalysis system has been developed and applied for the colorimetric analysis of routine urine examination indices using an Android app. By integrating the test paper sensor in the portable device for urinalysis,our system significantly improves the instability of conventional dipstick-based manual colorimetry, and the smartphone application used for color discrimination enhances the accuracy of the visual assessment of sample strips. Using a simple operation approach that takes ~ 2 min per test, our system can be applied as rapid urinalysis for routine check-ups.

Hygrothermal/UV Aging Effect on Visual Aspect and Mechanical Properties of Non-Woven Natural-Fiber Composites

This work aims at studying the effect of hygrothermal and UV cyclic aging on the tensile properties and esthetic characteristics of non-woven composites.The composite materials were thermo-compressed from non-woven mats made up of PP and flax or kenaf fibers.This works included evaluating the change in color appearance and analyzing the variations in tensile properties and damage mechanisms,depending on the aging time.The presence of the UV protection film on the composite surface showed its effectiveness against aging.From visual observations and measurement of colorimetric parameters,it has been proved effective in the reduction of the bleaching and yellowing of the composites.As regards the tensile tests,the UV protection film enabled to stabilize the Young’s modulus after 1-week aging for Kenaf/PP and after 3-weeks for Flax/PP.After 4-weeks aging,it halved the number of acoustic emission events related to interfacial decohesion and fiber slippage/pull out for Flax/PP and Kenaf/PP composites.

Adaptation and Validation of a Proteolytic Activity Methodology Using Dye-Crosslinked Substrate Tablets

Enzymatic activities are important to be quantified in products as enzymatic cleaners, which are used in medical and surgical devices reprocessing. Enzymatic activities are critical for the proper chemical cleaning that intends to remove solid organic dirt from inaccessible sites. The most important enzyme for this purpose is the protease, which is able to dissolve the main dirt attached to medical and surgical instruments. In this context, this study contributes to the development of a new proteolytic activity quantification method and its validation. The methodology is based on colorimetry and uses a UV-Vis spectrophotometer to measure the substrate hydrolysis by the blue color intensity, employing Protazyme AK tablets as substrate.

Self-Referencing Method for Relative Color Intensity Analysis Using Mobile-Phone

Mobile-phones have been widely explored on colorimetric evaluations. However, their use with different built-in image systems and acquisition configuration, in an environment with non-controlled illumination, limits the establishment of an accurate color analysis. To overcome this restriction, the determination of the absolute color of an object can be overlooked and a relative color value determined. In this work, we establish a new approach for spectroscopic evaluation based on cell-phone imaging, with no previous calibration, determining relative color values. The standalone relative color intensity method is evaluated under the use of four distinct mobile-phones and different illumination conditions. The capability to distinguish different color shades exploring the proposed self-referenced relative color intensity technique is appraised. Moreover, the potential use of the method is demonstrated by evaluating the chemical-adsorption process of Cysteamine molecules on gold nanoparticle surfaces. The proposed self-referenced technique can improve and expand the use of mobile-phones in spectroscopic applications.

Determination of total flavonoids and its antioxidant activity in the exocarp of Aronia melanocarpa

As a kind of berry food rich in flavonoids,the determination method of total flavonoids content of Aronia melanocarpa is of great significance.This paper compares the applicability of NaNO_(2)-Al(NO_(3))_(3)-NaOH colorimetry and AlCl_(3)colorimetry to total flavonoids content of the exocarp of Aronia melanocarpa by Ultraviolet-visible Spectrophotometry.At the same time,we determined hydroxyl radical(OH·-)inhibition rate,superoxide anion radical(O_(2)·-)inhibition rate and 1,1-diphenyl-2-picrylhydrazyl radical free radical(DPPH·)scavenging rate of total flavonoids extracted from Aronia melanocarpa.It is found that AlCl_(3)colorimetry has good repeatability,precision,and accuracy.The method is suitable for the determination of total flavonoids in the exocarp of Aronia melanocarpa.Thus,by the established method the content of total flavonoids in the exocarp of Aronia melanocarpa was determined as high as(36.711±0.034)mg/g.The results of antioxidant activity showed superoxide anion radical scavenging ability,hydroxyl radical scavenging ability and DPPH radical scavenging ability of the total flavonoids extract reached 45.33%,87.87%and 98.05%,respectively,indicating that it had good antioxidant activity.

Recent advances in photoelectrochemistry-coupled dual-modal biosensors:From constructions to biosensing applications

Precise and sensitive bioanalysis has been the major and urgent pursuit in pathologic diagnosis,food safety,environment monitoring,and drug evaluation.Photoelectrochemical(PEC)bioanalysis,as one of the most promising detection technologies,has rapidly expanded within the field of analysis.However,most of reported PEC analysis approaches still suffer from weak external anti-interference ability,high background,and the risk of false positive or negative errors due to their inherent single-signal readout.To overcome these shortcomings,new PEC-coupled dual-modal analysis approaches have been developed,where a dual-response signal can be derived through two completely different mechanisms and independent signal transduction pathways.This review introduces the basic principles of PEC biosensing and enumerates and classifies the substrate or probe selections,constructions,and applications of PEC-coupled dual-modal biosensors.Furthermore,the challenges and developmental prospects of PEC-coupled dual-mode sensing technologies are evaluated and discussed.We hope that this review will provide valuable insights into the latest advancements and practical applications of dual-mode PEC bioanalysis,which will be of great interest to those seeking to stay informed in this field.

Single nanozyme-based colorimetric biosensor for dopamine with enhanced selectivity via reactivity of oxidation intermediates

Reliable and selective sensing of dopamine(DA)is essential for early diagnosis of mental diseases.Among the various potential methods,nanozyme-based sensing systems have demonstrated promising sensitivity and reliability.However,owing to the lack of substrate specificity,it is challenging to selectively detect DA using nanozymes.Herein,based on the reactivity of the DA oxidation intermediates,we report a cascade colorimetric sensing system for the selective detection of DA using only a single nanozyme.It was disclosed that the oxidation product of DA catalyzed by Co-N-doped carbon sheets(Co-N-C,a common oxidase-like nanozyme),dopamine quinone(DAQ),showed significant biocatalytic electron-donating activity in the reduction of O_(2)to generate O_(2)·-.Further using O_(2)·-to oxidize3,3,5,5-tetramethylbenzidine(TMB),a colorimetric sensing platform for DA was constructed with a linear detection range of 50 nmol/L to 50μmol/L and a low limit of detection of 4 nmol/L.Thanks to the reactivity of the oxidation product,without any biometric units(such as nucleic acids,enzymes,and antibodies/antigens),the reaction selectivity of DA against other interferences(e.g.,ascorbic acid,adrenaline,5-hydroxytryptamine,and glutathione)was enhanced up to 71-fold.Beyond complicated cascade systems requiring at least two nanozymes,sophisticated artificial recognition via multiple interactions was simplified by exploiting the oxidative properties of product intermediates;thus,only a single common oxidase-like nanozyme was needed.This work offers a new strategy to enhance the selectivity of nanozymes for bioanalytical applications.

Recent Progress in Optical Sensors Based on MXenes Quantum Dots and MXenes Nanosheets

In recent years,MXenes,as a new promising two-dimensional material,have received extensive attentions in the fields of environmental remediation,catalysts,sensors,and energy storage.To broaden the applications of MXenes in sensing,MXenes nanosheets(MNSs) and MXenes quantum dots(MQDs) are prepared by physical etching or chemical oxidation.MNSs are monolayered or multilayered MXenes nanosheets within several nanometers in height,and can serve as the perfect reaction substrate and fluorescence quencher.MQDs are spherical,fluorescent MXenes QDs within several nanometers in size,which possess favorable stability and photo stability.Since the distinct features such as high conductivity,favorable hydrophilicity,biocompatibility,abundant surface functional groups,and easy functionalization,MNSs and MQDs show potential applications in the fields of anti-counterfeiting,environmental monitoring,biosensing and biomedicine.This review focuses on the research of MNS s/MQDs-based optical sensors,including colorimetric sensors,fluorescence sensors,electrochemiluminescence sensors,surface plasmon resonance sensors,and surface-enhanced Raman scattering sensors.Furthermore,the current challenges and prospects concerning MNSs/MQDs-based optical sensing techniques are discussed.

Construction of nanoreactors on TiO_(2)nanotube arrays as a POCT device for sensitive colorimetric detection

With increasing attention to personalized healthcare,miniaturized and easily implementable devices are desired for point-of-care testing(POCT).Herein,hydrophilic patterns were designed on freestanding TiO_(2)nanotube arrays(Ti NTs)as nanoreactors for a naked-eye colorimetric assay.With a high aspect ratio,TiN Ts can provide a long observation length combined with a limited volume.Moreover,by combining the photocatalytic property of TiO_(2)and spatiotemporal controllability of light,hydrophilic nanoreactors were fabricated with minimal volume,and thus the indicator and analyte are limited in a confined void by the hydrophobic surroundings,thus allowing a higher sensitivity for sensing.We believe the proposed sensing platform could provide a promising strategy in developing POCT devices for routine health monitoring.

Reagent-Loaded Annulus-Shaped Reactor on Filter-Paper with Virtual Colorimeter for Onsite Quick Detection of Chlorogenic Acid

In this work,a field-applicable,simple method for quick detecting chlorogenic acid(CGA)was developed.The method is based on CGA’s antioxidant property.CGA is reported to reduce a mixture solution of FeCl_(3)/K_(3)Fe(CN)_(6)to generate Fe_(4)[Fe(CN)_(6)]_(3),the Prussian blue,in an aqueous solution.This reaction was adopted in this work by using solid-ink printed annuli on a filter-paper as reaction vessels.The reagent is pre-loaded and dried within the solid ink printed circles.In a field test,a drop of a sample solution is directly applied to a reagent-loaded circle.The reaction product within the circle shows a blue color,which is detected by using an iPad(or cellphone)camera as a detector and a light-emitting diode flashlight lamp as a light source.A freely available RGB colorimeter program from Apple store was used to read light intensity of three colors:red,green,blue,and absorbance signal of red and blue light is calculated.The difference of absorbance signal of red light from that of blue light was found having linear relationship with CGA concentration in an aqueous sample solution.This simple method is sensitive with a detection limit of 1.0μg/mL for CGA in sample solution.The technique was used to analyze CGA concentration in green coffee extract,and the analytical results agree well with that obtained using a UV/Vis absorption spectrometric method.The real sample test results demonstrate the usefulness of this simple method for quick detecting CGA in green coffee extract products in field test applications.

Tunable catalytic activity of FeWO_(4) nanomaterials for sensitive assays of pyrophosphate ion and alkaline phosphatase activity

Alkaline phosphatase(ALP)activity and pyrophosphate ion(PPi)levels are remarkable for the human body functions such as signal transduction pathways and metabolism.Current quantitative methods mainly focus on developing complicated organic substrates or employing unstable metal ions as signal-regulated medium.Herein,we have developed a facile hydrothermal method for preparing Fe WO_(4)nanomaterials with intrinsic peroxidase-like activity and further confirmed that such a catalytic activity could be significantly enhanced by adjusting the size and oxygen vacancy content.More encouragingly,PPi can easily inhibit the catalytic activity of Fe WO_(4),whereas orthophosphate ions(Pi)cannot.Therefore,we constructed an Fe WO_(4)-based colorimetric assay for sensing PPi by means of the classical 3,3′,5,5′-tetramethylbenzidine-peroxidase chromogenic reaction.A facile and reliable ALP activity assay was also designed and developed because of the logical regulation of the peroxidase-like activity of Fe WO_(4)through the ALP-catalyzed hydrolysis of PPi into Pi.Based on the clear mechanism and mimetic-enzyme Fe WO_(4)-catalyzed amplification,the sensing system exhibited excellent performance and was able to evaluate ALP activity in real serum samples and screen for potential ALP inhibitors.The proposed mimetic enzyme-involved colorimetric assay provides an alternative pathway,and Fe WO_(4)nanomaterials with excellent performance have great potential for further biosensing and biomedical applications.

A new method to determine composition of sphalerite without secondary pollution based on CIELAB color space

Currently,most of the methods formineral materials analysis generate secondary pollution,which is detrimental to human health.For instance,traditionalmethods for sphalerite analysis in the zinc(Zn)smelting industry including chemical titration,atomic absorption spectrometry,and inductively coupled atomic emission spectroscopy.Colored indicators and toxic heavy metals are used in the analytical processes,causing severe pollution.For some methods,liquid is transformed into gaseous plasma,which is more dangerous to human health.Due to large quantities of sphalerite being used,secondary pollution cannot be ignored.This study proposes a green analysis method for the detection of sphalerite based on colorimetry,which does not generate secondary pollution.The results show that the strong substitution ability of iron(Fe)for Zn contributes to their inverse correlation in contents.The lattice parameters decrease with the increasing Fe content,resulting in a darker coloration.Here,key colorimetry parameters of L*,a*,and b*show clear linear correlations with the Zn and Fe contents.Compared with traditional approaches,this new method is environmental friendly with high sensitivity and accuracy.The relative error and relative standard deviation were less than 10%and 5%,respectively.This study provides a significant reference for nonpollution determination of other mineral materials.

Effect of Morinda Tinctoria Leaves Extract on the Corrosion Inhibition of Mild Steel in Acid Medium

The Morinda tinctoria (MT) plant leaves extract was prepared in aqueous and hydrochloric acid media and was used as corrosion inhibitor for mild steel in hydrochloric acid medium. MT is found to be an efficient inhibitor at room temperature and the efficiency decreases with increase in temperature. Results from colorimetric studies predict the amount of iron present in the test solution and the percentage inhibition efficiency values calculated from this data fit well with the weight loss experiments. The AC impedance studies reveal that the mild steel surface is positively charged and the process of inhibition is through charge transfer. Polarisation studies indicate the mixed nature of the inhibitor. Thermodynamic parameters obtained predict that the process of inhibition is a spontaneous one.