Monitoring saliva compositions for non-invasive detection of diabetes using a colorimetric-based multiple sensor.

The increasing population of diabetic patients, especially in developing countries, has posed a serious risk to the health sector, so that the lack of timely diagnosis and treatment process of diabetes can lead to threatening complications for the human lifestyle. Here, a multiple sensor was fabricated on a paper substrate for rapid detection and controlling the progress of the diabetes disease. The proposed sensor utilized the sensing ability of porphyrazines, pH-sensitive dyes and silver nanoparticles in order to detect the differences in saliva composition of diabetic and non-diabetic patients. A unique color map (sensor response) was obtained for each studied group, which can be monitored by a scanner. Moreover, a good correlation was observed between the colorimetric response resulting from the analysis of salivary composition and the fasting blood glucose (FBG) value measured by standard laboratory instruments. It was also possible to classify participants into two groups, including patients caused by diabetes and those were non-diabetic persons with a total accuracy of 88.9%. Statistical evaluations show that the multiple sensor can be employed as an effective and non-invasive device for continuous monitoring of diabetes, substantially in the elderly.

An origami-based colorimetric sensor for detection of hydrogen peroxide and glucose using sericin capped silver nanoparticles.

The hydrogen peroxide (H2O2) measurement is considered highly important in industrial wastewater quality assessment, environmental protection, and disease detection. Here, a simple high-performance paper-based sensor is proposed for rapid and in situ detection of H2O2. To this end, 3,3',5,5'-tetramethylbenzidine is embedded in the sensor to act as a color indicator, whose reaction with hydrogen peroxide is catalyzed by a silver nanozyme modified by sericin. The result of the reaction clarified by the appearance of blue color in the sensor detection zone is received by a portable scanner, while also calculating its intensity by image analysis software. This method is sensitive to hydrogen peroxide in the concentration range of 0.5‒240 mg/dL, providing a detection limit of 0.15 mg/dL. The ability of the sensor to determine glucose is also evaluated by adding a layer containing glucose oxidase enzyme to the sensor structure. A desirable response is obtained in the range of 1.0‒160 mg/dL, together with a detection limit of 0.37 mg/dL. Accordingly, the proposed sensor shows satisfactory results compared to clinical methods for monitoring the amount of glucose in biological samples such as serum and saliva.

Visual diagnosis of COVID-19 disease based on serum metabolites using a paper-based electronic tongue.

This study aims to use a paper-based sensor array for point-of-care detection of COVID-19 diseases. Various chemical compounds such as nanoparticles, organic dyes and metal ion complexes were employed as sensing elements in the array fabrication, capturing the metabolites of human serum samples. The viral infection caused the type and concentration of serum compositions to change, resulting in different color responses for the infected and control samples. For this purpose, 118 serum samples of COVID-19 patients and non-COVID controls both men and women with the age range of 14-88 years were collected. The serum samples were initially subjected to the sensor, followed by monitoring the variation in the color of sensing elements for 5 min using a scanner. By taking into consideration the statistical information, this method was capable of discriminating COVID-19 patients and control samples with 83.0% accuracy. The variation of age did not influence the colorimetric patterns. The desirable correlation was observed between the sensor responses and viral load values calculated by the PCR test, proposing a rapid and facile way to estimate the disease severity. Compared to other rapid detection methods, the developed assay is cost-effective and user-friendly, allowing for screening COVID-19 diseases reliably.

Non-invasive detection of COVID-19 using a microfluidic-based colorimetric sensor array sensitive to urinary metabolites.

A colorimetric sensor array designed on a paper substrate with a microfluidic structure has been developed. This array is capable of detecting COVID-19 disease by tracking metabolites of urine samples. In order to determine minor metabolic changes, various colorimetric receptors consisting of gold and silver nanoparticles, metalloporphyrins, metal ion complexes, and pH-sensitive indicators are used in the array structure. By injecting a small volume of the urine sample, the color pattern of the sensor changes after 7 min, which can be observed visually. The color changes of the receptors (recorded by a scanner) are subsequently calculated by image analysis software and displayed as a color difference map. This study has been performed on 130 volunteers, including 60 patients infected by COVID-19, 55 healthy controls, and 15 cured individuals. The resulting array provides a fingerprint response for each category due to the differences in the metabolic profile of the urine sample. The principal component analysis-discriminant analysis confirms that the assay sensitivity to the correctly detected patient, healthy, and cured participants is equal to 73.3%, 74.5%, and 66.6%, respectively. Apart from COVID-19, other diseases such as chronic kidney disease, liver disorder, and diabetes may be detectable by the proposed sensor. However, this performance of the sensor must be tested in the studies with a larger sample size. These results show the possible feasibility of the sensor as a suitable alternative to costly and time-consuming standard methods for rapid detection and control of viral and bacterial infectious diseases and metabolic disorders.

Mask assistance to colorimetric sniffers for detection of Covid-19 disease using exhaled breath metabolites.

According to World Health Organization reports, large numbers of people around the globe have been infected or died for Covid-19 due to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Researchers are still trying to find a rapid and accurate diagnostic method for revealing infected people by low viral load with the overriding goal of effective diagnostic management. Monitoring the body metabolic changes is known as an effective and inexpensive approach for the evaluation of the infected people. Here, an optical sniffer is introduced to detect exhaled breath metabolites of patients with Covid-19 (60 samples), healthy humans (55 samples), and cured people (15 samples), providing a unique color pattern for differentiation between the studied samples. The sniffer device is installed on a thin face mask, and directly exposed to the exhaled breath stream. The interactions occurring between the volatile compounds and sensing components such as porphyrazines, modified organic dyes, porphyrins, inorganic complexes, and gold nanoparticles allowing for the change of the color, thus being tracked as the sensor responses. The assay accuracy for the differentiation between patient, healthy and cured samples is calculated to be in the range of 80%-84%. The changes in the color of the sensor have a linear correlation with the disease severity and viral load evaluated by rRT-PCR method. Interestingly, comorbidities such as kidney, lung, and diabetes diseases as well as being a smoker may be diagnosed by the proposed method. As a powerful detection device, the breath sniffer can replace the conventional rapid test kits for medical applications.

A colorimetric electronic tongue for point-of-care detection of COVID-19 using salivary metabolites.

The monitoring of profile concentrations of chemical markers in saliva samples can be used to diagnose COVID-19 patients, and differentiate them from healthy individuals. Here, this purpose is achieved by designing a paper-based colorimetric sensor with an origami structure, containing general receptors such as pH-sensitive organic dyes, Lewis donors or acceptors, functionalized nanoparticles, and ion metal complexes. The color changes taking place in the receptors in the presence of chemical markers are visually observed and recorded with a digital instrument. Different types and amounts of the chemical markers provide the sensor with a unique response for patients (60 samples) or healthy (55 samples) individuals. These two categories can be discriminated with 84.3% accuracy. This study evidences that the saliva composition of cured and healthy participants is different from each other with accuracy of 85.7%. Moreover, viral load values obtained from the rRT-PCR method can be estimated by the designed sensor. Besides COVID-19, it may possible to simultaneously identify smokers and people with kidney disease and diabetes using the specified electronic tongue. Due to its high efficiency, the prepared paper device can be employed as a rapid detection kit to detect COVID-19.

Nanomaterials-based hyperthermia: A literature review from concept to applications in chemistry and biomedicine.

Hyperthermia, the mild elevation of temperature to 40-45 °C, can induce cancer cell death and enhance the effects of radiotherapy and chemotherapy. Due to the nature of hyperthermia, especially their ability to combine nanotechnology, hyperthermia possesses the potential to open a novel paradigm for the therapeutic strategies. However, achievement of its full potential as a clinically relevant treatment modality has been restricted by its inability to effectively and preferentially heat malignant cells. The main challenge of current hyperthermia treatment is to adequately heat whole volumes of deep-seated tumors without overheating surrounding healthy tissues. So, hyperthermia is under clinical trials (research study with people) and is not widely available. In this Review, we summarize a basic knowledge of hyperthermia before focusing on their applications to the cancer therapy and synthesis. We try to give a comprehensive view of the role of nanomaterials in the designing of hyperthermia-based therapeutic protocols and compare the studies in this field with the purpose of providing a source of helpful information for planning forthcoming hyperthermia researches. However, establishing comparisons between hyperthermia studies is a challenge due to the widely different conditions used by different authors, which, in some cases, is aggravated by the lack of crucial information concerning a certain aspect of the procedure.

Disposable Paper-Based Biosensors for the Point-of-Care Detection of Hazardous Contaminations-A Review.

The fast detection of trace amounts of hazardous contaminations can prevent serious damage to the environment. Paper-based sensors offer a new perspective on the world of analytical methods, overcoming previous limitations by fabricating a simple device with valuable benefits such as flexibility, biocompatibility, disposability, biodegradability, easy operation, large surface-to-volume ratio, and cost-effectiveness. Depending on the performance type, the device can be used to analyze the analyte in the liquid or vapor phase. For liquid samples, various structures (including a dipstick, as well as microfluidic and lateral flow) have been constructed. Paper-based 3D sensors are prepared by gluing and folding different layers of a piece of paper, being more user-friendly, due to the combination of several preparation methods, the integration of different sensor elements, and the connection between two methods of detection in a small set. Paper sensors can be used in chromatographic, electrochemical, and colorimetric processes, depending on the type of transducer. Additionally, in recent years, the applicability of these sensors has been investigated in various applications, such as food and water quality, environmental monitoring, disease diagnosis, and medical sciences. Here, we review the development (from 2010 to 2021) of paper methods in the field of the detection and determination of toxic substances.

Recovered fluorescence of the Cd-nanocluster-Hg(II) system based on experimental results and computational methods.

Human Serum Albumin, a plasma protein existing in abundance, was selected as a template and reducing agent for the formation of CdNCs due to two factors: its stability and low cost. In the presence of human serum albumin (HSA), a selective and sensitive, low-cost, environmental friendly, and label-free off-on fluorescent sensor was synthesized and characterized for a bioaccumulating and toxic heavy metal, Hg2+ and biothiols. HSA - CdNCs can specifically recognize Hg2+ through aggregating NCs and causing fluorescence quenching. Subsequently, with increase in the concentration of biothiols, Hg2+ was eliminated from the surface of NC, while the fluorescence was restored. The calculated limits of detection (LOD) were 55 pM for Hg(II) and 14 nM for GSH, respectively. The assay was capable of detecting Hg2+ ions and GHS at different concentrations in the range of 0.008 to 8530 nM and 7.5-5157 nM, respectively. Furthermore, the appropriate molecular mechanics (MM) as well as quantum mechanical (QM) methods were performed to optimize and the theoretical investigation of the discussed HSA-profile structures and its interactions with the Cd-NCs (one atom of Cd), Hg2+ and glutathione (G).

A nanoscale genosensor for early detection of COVID-19 by voltammetric determination of RNA-dependent RNA polymerase (RdRP) sequence of SARS-CoV-2 virus.

A voltammetric genosensor has been developed for the early diagnosis of COVID-19 by determination of RNA-dependent RNA polymerase (RdRP) sequence as a specific target of novel coronavirus. The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) uses an RdRP for the replication of its genome and the transcription of its genes. Here, the silver ions (Ag+) in the hexathia-18-crown-6 (HT18C6) were used for the first time as a redox probe. Then, the HT18C6(Ag) incorporated carbon paste electrode (CPE) was further modified with chitosan and PAMAM dendrimer-coated silicon quantum dots (SiQDs@PAMAM) for immobilization of probe sequences (aminated oligonucleotides). The current intensity of differential pulse voltammetry using the redox probe was found to decrease with increasing the concentration of target sequence. Based on such signal-off trend, the proposed genosensor exhibited a good linear response to SARS-CoV-2 RdRP in the concentration range 1.0 pM-8.0 nM with a regression equation I (µA) = - 6.555 log [RdRP sequence] (pM) + 32.676 (R2 = 0.995) and a limit of detection (LOD) of 0.3 pM. The standard addition method with different spike concentrations of RdRP sequence in human sputum samples showed a good recovery for real sample analysis (> 95%). Therefore, the developed voltammetric genosensor can be used to determine SARS-CoV-2 RdRP sequence in sputum samples. PAMAM-functionalized SiQDs were used as a versatile electrochemical platform for the SARS-CoV-2 RdRP detection based on a signal off sensing strategy. In this study, for the first time, the silver ions (Ag+) in the hexathia-18-crown-6 carrier were applied as an electrochemical probe.

Origami paper analytical assay based on metal complex sensor for rapid determination of blood cyanide concentration in fire survivors.

Cyanide-based blood poisoning can seriously damage fire victims and cause death if not detected quickly. Previous conventional methods require laboratory equipment, which are expensive and increase the duration of the analysis. Here, a simple origami based microfluidic device was introduced for point of need detection of blood cyanide concentration in people involved in fire. The device is made of four layers of paper. Each layer was in the size of 1 × 1 cm folded on each other. In this work, the blood sample was acidified by trichloroacetic acid to separate cyanide from methaemoglobin in the form of HCN gas. The produced gas released into borate buffer to recover free cyanide ions which interacted with the Pt complex ([Pt(p-MeC6H4)2(phen)]) used as a receptor in this study. Optimized conditions were applied to have a suitable interaction causing the color of the receptor to change from yellow to colorless. The color changes were recorded by a smartphone, and the sensor response was calculated by the routine image analysis software. The assay was capable of determining cyanide ions at different concentrations in the range of 1.0 to 100.0 µmol L-1. The detection limit of these determination was equal to 0.4 µmol L-1. The assay responses were not affected by the interfering species. As a practical analysis, the proposed sensor was applied to determine cyanide ions in the blood sample of 20 studied fire survivors and 10 controls with high accuracy.

A paper-based device for the colorimetric determination of ammonia and carbon dioxide using thiomalic acid and maltol functionalized silver nanoparticles: application to the enzymatic determination of urea in saliva and blood.

A colorimetric assay was developed which has the capability of determining urea in biological samples. It is an origami paper-based sensor consisting of silver nanoparticles that were synthesized by using two different capping agents: thiomalic acid and maltol. The function of the assay relied on hydrolysis of urea to ammonia and carbon dioxide in the presence of urease. The products interacted with nanoparticles which caused aggregation. Interestingly, thiomalic acid capped with silver nanoparticles were selective to ammonia, and the other nanoparticles synthesized by maltol responded to carbon dioxide. These interactions turned the color of nanoparticles from yellow to brown and red, respectively. The resulting colorations were captured by a floatable scanner. A routine image analysis software was utilized to provide the response of the assays. The method was applied to individually determine ammonia, carbon dioxide, and urea. The linear range was 0.06 mg.dL-1-170.0 mg.dL-1 for ammonia, 0.08 mg.dL-1-220.0 mg.dL-1 for carbon dioxide, and 0.5 mg.dL-1-200.0 mg.dL-1 for urea. The respective limits of detection were 0.03 mg.dL-1, 0.06 mg.dL-1, and 0.18 mg.dL-1. No interferences were found in the detremination of urea. The method demonstrates a reliable performance for determination of urea in both saliva and blood samples. Graphical Abstract Schematic representation of paper based colorimetric sensor based on silver nanoparticles for both qualitative and quantitative analyses of urea in biological samples.

Colorimetric aggregation assay based on array of gold and silver nanoparticles for simultaneous analysis of aflatoxins, ochratoxin and zearalenone by using chemometric analysis and paper based analytical devices.

A paper based sensor array is presented to discriminate and determine five mycotoxins classified into three categories, namely aflatoxins, ochratoxins and zearalenone. The gold and silver nanoparticles, synthesized by three different reducing or capping agents, were employed as sensing elements of the fabricated device. These nanoparticles were poured onto hydrophilic circular zones embedded on the hydrophobic substrate. The response of the assay is dependent on the aggregation of nanoparticles for interaction with mycotoxins. Due to aggregation, the gold and silver nanoparticles changed to purple and brown, respectively. Color changes provide unique colorimetric signatures conducive to recognizing the type of mycotoxin, identifying its chemical structure, and finding the fungi that produce it. The discrimination ability of the assay was investigated by both supervised (linear discriminate analysis) and unsupervised (principle component analysis and hierarchical cluster analysis) pattern recognition methods. The assay was applied to the point of need determination of aflatoxin B1, aflatoxin G1, aflatoxin M1, ochratoxin A and zearalenone with a detection limit of 2.7, 7.3, 2.1, 3.3 and 7.0 ng.mL-1, respectively. The fabricated device has high potential of simultaneously determining the mycotoxins in pistachio, wheat, coffee and milk with the help of partial least square method. The root mean square errors for prediction of PLS model were 5.7, 5.2, 1.5, 7.2 and 2.9 for aflatoxin B1, aflatoxin G1, aflatoxin M1, ochratoxin A and zearalenone, respectively. Graphical abstractSchematic representation of paper based colorimetric sensor array based on gold and silver nanoparticles for both qualitative and quantitative analysis of aflatoxins, ochratoxin and zearalenone.

Photocatalytic degradation of monoethanolamine in wastewater using nanosized TiO2 loaded on clinoptilolite.

The use of titanium dioxide (TiO(2)) as photocatalyst to degrade the organic compounds is an effective method of oxidation process and has been widely studied in environmental engineering. In this investigation photocatalytic degradation of monoethanolamine (MEA) using TiO(2) (in form of anatase) loaded on surface of clinoptilolite (CP) (TiO(2)-CP) in wastewater was studied. The surface interaction between TiO(2) and CP was investigated by means of transmission electron microscope (TEM), atom force microscope (AFM), IR and X-ray diffraction (XRD). Then the effects of some parameters such as pH, amount of photocatalyst, and initial concentration of MEA on degradation percentage of MEA were examined. The obtained results show that the TiO(2)-CP is an active photocatalyst as compared with TiO(2) nanopowders. All these results indicated that this proposed method can be useful for the development of wastewater treatment applications.