A colorimetric test for the evaluation of the insecticide content of LLINs used on Bioko Island, Equatorial Guinea.

BACKGROUND: Insecticide-treated nets and indoor residual spraying of insecticides are used as the vector control interventions in the fight against malaria. Measuring the actual amount of deposits of insecticides on bed nets and walls is essential for evaluating the quality and effectiveness of the intervention. A colorimetric "Test Kit" designed for use as a screening tool, able to detect the type II pyrethroids on fabrics and sprayed walls, was used for the first time to detect deltamethrin on long-lasting insecticidal nets (LLINs) deployed on Bioko Island, Equatorial Guinea. METHODS: LLINs were analysed using the colorimetric Test Kit performed in situ, which leads to the formation of an orange-red solution whose depth of colour indicates the amount of type II pyrethroid on the net. The kit results were validated by measuring the amount of extracted insecticide using high-performance liquid chromatography (HPLC) with diode array detection (DAD). RESULTS: Deltamethrin concentration was determined for 130 LLINs by HPLC-DAD. The deltamethrin concentration of these nets exhibited a significant decrease with the age of the net from 65 mg/m2 (< 12 months of use) to 31 mg/m2 (> 48 months; p < 0.001). Overall, 18% of the nets being used in households had < 15 mg/m2 of deltamethrin, thus falling into the "Fail" category as assessed by the colorimetric Test Kit. This was supported by determining the bio-efficacy of the nets using the WHO recommended cone bioassays. The Test Kit was field evaluated in situ and found to be rapid, accurate, and easy to use by people without laboratory training. The Test Kit was shown to have a reliable linear relationship between the depth of colour produced and deltamethrin concentration (R2 = 0.9135). CONCLUSION: This study shows that this colorimetric test was a reliable method to assess the insecticidal content of LLINs under operational conditions. The Test Kit provides immediate results and offers a rapid, inexpensive, field-friendly alternative to the complicated and costly methods such as HPLC and WHO cone bioassays which also need specialist staff. Thus, enabling National Malaria Control Programmes to gain access to effective and affordable monitoring tools for use in situ.

A Microdroplet-Based Colorimetric Sensing Platform on a CMOS Imager Chip.

Interest in mobile chemical sensors is on the rise, but significant challenges have restricted widespread adoption into commercial devices. To be useful these sensors need to have a predictable response, easy calibration, and be integrable with existing technology, preferably fitting on a single chip. With respect to integration, the CMOS imager makes an attractive template for an optoelectronic sensing platform. Demand for smartphones with cameras has driven down the price and size of CMOS imagers over the past decade. The low cost and accessibility of these powerful tools motivated us to print chemical sensing elements directly on the surface of the photodiode array. These printed colorimetric microdroplets are composed of a nonvolatile solvent so they remain in a uniform and homogeneous solution phase, an ideal medium for chemical interactions and optical measurements. By imaging microdroplets on the CMOS imager surface we eliminated the need for lenses, dramatically scaling down the size of the sensing platform to a single chip. We believe the technique is generalizable to many colorimetric formulations, and as an example we detected gaseous ammonia with Cu(II). Limits of detection as low as 27 ppb and sensor-to-sensor variation of less than 10% across multiple printed arrays demonstrated the high sensitivity and repeatability of this approach. Sensors generated this way could share a single calibration, greatly reducing the complexity of incorporating chemical sensors into mobile devices. Additional testing showed the sensor can be reused and has good selectivity; sensitivity and dynamic range can be tuned by controlling droplet size.

Evaluation of SARS-CoV-2 neutralizing antibodies using a CPE-based colorimetric live virus micro-neutralization assay in human serum samples.

The micro-neutralization assay is a fundamental test in virology, immunology, vaccine assessment, and epidemiology studies. Since the SARS-CoV-2 outbreak at the end of December 2019 in China, it has become extremely important to have well-established and validated diagnostic and serological assays for this new emerging virus. Here, we present a micro-neutralization assay with the use of SARS-CoV-2 wild type virus with two different methods of read-out. We evaluated the performance of this assay using human serum samples taken from an Italian seroepidemiological study being performed at the University of Siena, along with the human monoclonal antibody CR3022 and some iper-immune animal serum samples against Influenza and Adenovirus strains. The same panel of human samples have been previously tested in enzyme-linked immunosorbent assay (ELISA) as a pre-screening. Positive, borderline, and negative ELISA samples were evaluated in neutralization assay using two different methods of read-out: subjective (by means of an inverted optical microscope) and objective (by means of a spectrophotometer). Our findings suggest that at least 50% of positive ELISA samples are positive in neutralization as well, and that method is able to quantify different antibody concentrations in a specific manner. Taken together, our results confirm that the colorimetric cytopathic effect-based microneutralization assay could be used as a valid clinical test method for epidemiological and vaccine studies.

Development of standardized method for the quantification of azo dyes by UV-Vis in binary mixtures.

The azo dyes, Yellow 5 (Y5), Red 2 (R2) and Blue 1 (B1), quantified in solutions and in mixtures of binary dyes, were studied by means of UV-Vis spectroscopy. In this work was used a CIE algorithm developed in Visual Basic for Applications (VBA). The CIE algorithm is based on the tristimulus chromaticity diagram, as an alternative to the shielding effect that arises in dye mixtures, and it can also be applied to complex quantification methods such as HPLC (High Performance Liquid Chromatography). The results obtained through of the algorithm, showed a higher accuracy from 97 to 99% in relation with similar UV-Vis quantification methods. In contrast, linear methods only managed to reach an accuracy from 78 to 98%. Additionally, the algorithm yielded significant similar values to the UHPLC reference method. The results showed that the method CIE algorithm was accessible and reliable to quantify binary mixtures of the dyes used which suggests the possibility to apply this method on other dyes, within the limits of quantification obtained in this study (0.076-24.56 mg/L) and the pH values from 2 to 10.

Development and validation of an economical uric acid-Fe3+/Fe2+-ferrozine-based colorimetric assay to estimate uric acid level of pure and biological samples.

This work presents the development and validation of a simple, rapid, and cost-effective spectrophotometric method for quantitative analysis of uric acid in biological samples. The method relies upon uric acid-led reduction of Fe(III) to Fe(II) of sample/standard solutions which stoichiometrically engages ferrozine to form a magenta-colored complex. Different parameters including pH, metal and chelator concentrations, temperature, etc., were optimized for the maximum intensity and stability of the complex. The uric acid concentrations of synthetic/plasma solutions were determined by comparing the color intensity of Fe(ferrozine)3 2+ complex produced by test solution with the standard curve formed by known uric acid concentrations. The method was validated in accordance with ICH guidelines and subjected to human plasma analysis. The results obtained were compared with a reference (enzymatic) method which revealed that there was no significant difference between the two methods at 95% confidence level. The method is highly specific, precise, linear, accurate, and robust.

Hemin@carbon dot hybrid nanozymes with peroxidase mimicking properties for dual (colorimetric and fluorometric) sensing of hydrogen peroxide, glucose and xanthine.

The multifunctional hemin@carbon dot hybrid nanozymes (hemin@CD) with simultaneous peroxidase-like activity and fluorescence signalling property was prepared for the first time. Based on these properties, hemin@CD was applied to develop a dual-channel fluorescent probe for H2O2 and H2O2-based biocatalytic systems. By virtue of the peroxidase-like activity, hemin@CD can catalyze the oxidative coupling of 4-aminoantipyrine with phenol in the presence of H2O2 to form a pink-red quinoneimine dye with a maximum absorbance at 505 nm. Under the excitation wavelength of 480 nm, the green fluorescence of hemin@CD peaks at 540 nm and is quenched by the generated quinoneimine dye due to an inner filter effect, and also by H2O2 because of dynamic quenching. Thus, a colorimetric and fluorimetric dual-channel optical probe for H2O2 is obtained. Due to the glucose/xanthine transformations under formation of H2O2 by the relevant oxidase catalysis, the probe can be applied for detection of glucose and xanthine. The colorimetric detection limits for H2O2, glucose and xanthine are 0.11, 0.15, 0.11 µM, and the and fluorimetric detection limits are 0.15, 0.15, 0.12 µM, respectively. Graphical abstractSchematic representation of the colorimetric and fluorimetric dual probe for H2O2, glucose and xanthine based on the multifunctional emin@carbon dot) hybrid nanozymes with simultaneous peroxidase-like activity and fluorescence signalling property.

Smart Chip for Visual Detection of Bacteria Using the Electrochromic Properties of Polyaniline.

Finding fast and reliable ways to detect pathogenic bacteria is crucial for addressing serious public health issues in clinical, environmental, and food settings. Here, we present a novel assay based on the conversion of an electrochemical signal into a more convenient optical readout for the visual detection of Escherichia coli. Electropolymerizing polyaniline (PANI) on an indium tin oxide screen-printed electrode (ITO SPE), we achieved not only the desired electrochromic behavior but also a convenient way to modify the electrode surface with antibodies (taking advantage of the many amine groups of PANI). Applying a constant potential to the PANI-modified ITO SPE induces a change in their oxidation state, which in turn generates a color change on the electrode surface. The presence of E. coli on the electrode surface increases the resistance in the circuit affecting the PANI oxidation states, producing a different electrochromic response. Using this electrochromic sensor, we could measure concentrations of E. coli spanning 4 orders of magnitude with a limit of detection of 102 colony forming unit per 1 mL (CFU mL-1) by the naked eye and 101 CFU mL-1 using ImageJ software. In this work we show that merging the sensitivity of electrochemistry with the user-friendliness of an optical readout can generate a new and powerful class of biosensors, with potentially unlimited applications in a variety of fields.

MODS-Wayne, a Colorimetric Adaptation of the Microscopic-Observation Drug Susceptibility (MODS) Assay for Detection of Mycobacterium tuberculosis Pyrazinamide Resistance from Sputum Samples.

Although pyrazinamide (PZA) is a key component of first- and second-line tuberculosis treatment regimens, there is no gold standard to determine PZA resistance. Approximately 50% of multidrug-resistant tuberculosis (MDR-TB) and over 90% of extensively drug-resistant tuberculosis (XDR-TB) strains are also PZA resistant. pncA sequencing is the endorsed test to evaluate PZA susceptibility. However, molecular methods have limitations for their wide application. In this study, we standardized and evaluated a new method, MODS-Wayne, to determine PZA resistance. MODS-Wayne is based on the detection of pyrazinoic acid, the hydrolysis product of PZA, directly in the supernatant of sputum cultures by detecting a color change following the addition of 10% ferrous ammonium sulfate. Using a PZA concentration of 800 µg/ml, sensitivity and specificity were evaluated at three different periods of incubation (reading 1, reading 2, and reading 3) using a composite reference standard (MGIT-PZA, pncA sequencing, and the classic Wayne test). MODS-Wayne was able to detect PZA resistance, with a sensitivity and specificity of 92.7% and 99.3%, respectively, at reading 3. MODS-Wayne had an agreement of 93.8% and a kappa index of 0.79 compared to the classic Wayne test, an agreement of 95.3% and kappa index of 0.86 compared to MGIT-PZA, and an agreement of 96.9% and kappa index of 0.90 compared to pncA sequencing. In conclusion, MODS-Wayne is a simple, fast, accurate, and inexpensive approach to detect PZA resistance, making this an attractive assay especially for low-resource countries, where TB is a major public health problem.

Enhanced synergistic effects from multiple iron oxide nanoparticles encapsulated within nitrogen-doped carbon nanocages for simple and label-free visual detection of blood glucose.

Hollow-structured carbon materials play a crucial role in research of biosensors, energy storage and nanomedicine as a kind of material with advantages like high surface area, tunable pore volume, excellent mechanical properties, and good biocompatibility. Herein, we developed a simple, facile and controllable method for synthesis of Fe3O4 nanoparticles encapsulated in hollow carbon nanocages (FNHCs) with SiO2 nanospheres as a sacrificial template. Owing to the unique structure of multiple Fe3O4 nanoparticles cores integrated with N-doped carbon nanocages, the as-synthesized FNHCs exhibited greatly enhanced peroxidase mimicking activity with extremely high signal-to-noise ratio of ∼91 fold. Also, it was found that the FNHCs possessed a higher peroxidase-like activity than that of other similar-structured Fe3O4 architectures (e.g. Fe3O4@C NPs). The resulting steady-state kinetic curve demonstrated the enzymatic activity of FNHCs with classic Michaelis-Menton kinetics following a ping-pong mechanism. On the basis of the superior enzymatic activity, the FNHCs performed as a high-efficiency peroxidase mimic, realizing facile, label-free, highly sensitive/selective colorimetric detection of H2O2 and glucose. Furthermore, the colorimetric sensor successfully determined glucose in patients' serum samples with high accuracy and precision, suggesting great potential for real applications.

Sunlight caused interference in outdoor N, N-diethyl-p-phenylenediamine colorimetric measurement for residual chlorine and the solution for on-site work.

Chlorination is the most common method to control water qualities, in some case on-site outdoor measurements are required to measure easily-decaying residual chlorine concentration appropriately without delay. In this study sunlight-induced unexpected colour development (UCD) of N, N-diethyl-p-phenylenediamine (DPD) colorimetric measurement was studied under several sun exposure conditions. The colour development level was evaluated with reference to chlorine concentration (mg/L) and relationships between colour development rate (mg/L min) and intensities of solar were investigated. UCD was found to be related to both exposure intensity and time. By means of exposure experiment under specific wavelength of ultraviolet (UV), it was confirmed that both middle and short wavelength of UV radiation being responsible for such an unexpected measurement. Consequently, a simple device was designed using three commercially available anti-UV films, one of which could effectively prevent the UCD from direct sun exposure.

A hairpin-type DNA probe for direct colorimetric detection of endonuclease activity and inhibition based on the deaggregation of gold nanoparticles.

A method is described for the determination of the activity of endonuclease. It based on the deaggregation of gold nanoparticles (AuNPs) aggregated by the action of poly(diallyldimethylammonium chloride) (PDDA). A single-stranded DNA (ssDNA) is released after enzymatic cleavage catalyzed by endonuclease. The released fragments bind electrostatically to PDDA and inhibit the PDDA-induced aggregation of AuNPs. This is accompanied by a color change from blue to red and a decrease in the absorption ratio (A630/A520). Under the optimal conditions, this ratio increases linearly in the 0.001 to 1 U·µL-1 EcoRI endonuclease activity range. The detection limit is of 2 × 10-4 U·µL-1 which is much better or at least comparable to previous reports. The method is deemed to have wide scope in that it may be used to study other endonuclease activity (such as BamHI) by simply changing the specific recognition site of the hairpin-like DNA probe. The assay may also be employed to screening for inhibitors of EcoRI endonuclease. Graphical abstract Schematic presentation of the colorimetric assay based on the deaggregation of AuNPs for the detection of endonuclease activity. A single-stranded sequence (ssDNA) is released by the EcoRI cleavage, which electrostatically binds to PDDA and inhibits the PDDA-induced aggregation of AuNPs accompanying with a color change from blue to red.

Highly Selective, Aptamer-Based, Ultrasensitive Nanogold Colorimetric Smartphone Readout for Detection of Cd(II).

A highly selective and sensitive method for Cd(II) detection was developed based on aptamer and gold nanoparticles (AuNPs) combined with a colorimetric smartphone readout. The experimental conditions such as reaction time of polydiene dimethyl ammonium chloride (PDDA) and AuNPs, PDDA dose, time of aptamer and PDDA incubation, and aptamer concentration were optimized. Under the optimized conditions, the color and red(R) value of the solution was concentration-dependent on Cd(II). The proposed method exhibited a linear range of 1-400 ng/mL (r2 = 0.9794) with a limit of detection (LOD) of 1 ng/mL. This method had been successfully applied to test and quantify Cd(II) in water and rice samples, and the results were in full agreement with those from the atomic absorption spectrometer. Therefore, low-cost colorimetry demonstrated its potential for practical application in visual or quantitative detection with a smartphone. This approach can be readily applied to other analytes.

A colorimetric mercury(II) assay based on the Hg(II)-stimulated peroxidase mimicking activity of a nanocomposite prepared from graphitic carbon nitride and gold nanoparticles.

A one-step reduction method was used for the preparation of stable graphitic carbon nitride-gold nanoparticles (g-C3N4-Au) nanocomposites from ultrathin g-C3N4 nanosheets and chloroauric acid by using NaBH4 as a reducing agent under ultrasonication. The nanocomposites were characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis absorption and fluorescence spectroscopy etc. The results revealed that the gold nanoparticles (AuNPs) are uniformly formed on the g-C3N4 nanosheets. It is found that the peroxidase-like catalytic activity of this nanocomposite for the oxidation of 3,3',5,5'-tetramethylbenzidine by H2O2 to form a blue-colored product is strongly enhanced in the presence of Hg(II). Based on this phenomenon, a sensitive "turn-on" colorimetric assay for Hg(II) was developed that works at physiological pH values. Under optimal conditions, the absorption signal at 652 nm increases linearly with Hg(II) concentration in the range from 5 to 500 nM. A detection limit as low as 3.0 nM was achieved. This assay has excellent selectivity over other metal ions. It was successfully applied to the determination of Hg(II) in real water samples. The method is cost-effective, rapid, and allows for visual detection. Graphical abstract The nanocomposite composed of graphitic carbon nitride (g-C3N4) and gold nanoparticles (g-C3N4-AuNPs) can catalyze tetramethylbenzidine (TMB) oxidation by H2O2 to produce light-blue product (oxTMB). The peroxidase-like activity of g-C3N4-AuNPs can be greatly enhanced by Hg2+, thus increases the amount of the blue product formed.

Colorimetric determination of the activity of alkaline phosphatase based on the use of Cu(II)-modulated G-quadruplex-based DNAzymes.

A colorimetric detection scheme is introduced for the determination of alkaline phosphatase (ALP) activity based on Cu(II)-modulated G-quadruplex-based DNAzymes. It is exploiting the strong affinity of Cu(II) for pyrophosphate (PPi) upon which the cofactor PPi is trapped by Cu(II). Hence, the activity of the DNAzyme is inhibited. ALP catalyzes the hydrolysis of PPi, causing the release of Cu(II). DNAzyme, in turn, is activated and catalyzes the cleavage of the DNA probe substrate. The released G-rich sequence folds into the G-quadruplex, which can bind hemin and catalyze the oxidation of 2,2'-azinobis (3-ethylbenzothiozoline)-6-sulfonate (ABTS), and this leads to an increase in absorbance at 420 nm. Absorbance increases linearly with increasing ALP activity in 0.07 to 300 U.L-1 range, with a 70 mU.L-1 detection limit. The method was applied in ALP inhibition tests and to the determination of ALP activity in spiked serum samples where it gave satisfactory results. Graphical abstract A colorimetric method has been developed for the detection of alkaline phosphatase based on the use of Cu(II)-modulated G-quadruplex-based DNAzymes.

On site visual detection of Porphyromonas gingivalis related periodontitis by using a magnetic-nanobead based assay for gingipains protease biomarkers.

Porphyromonas gingivalis (P. gingivalis) is a pathogen causing periodontitis. A rapid assay is described for the diagnosis of periodontal infections related to P. gingivalis. The method is making use of gingipains, a group of P. gingivalis specific proteases as a detection biomarker. Magnetic-nanobeads were labeled with gingipain-specific peptide substrates and immobilized on a gold biosensing platform via gold-thiol linkage. As a result of this, the color of the gold layer turns black. Upon cleavage of the immobilized substrates by gingipains, the magnetic-nanobeads-peptide fragments were attracted by a magnet so that the golden surface color becomes visible again. This assay is highly sensitive and specific. It is capable of detecting as little as 49 CFU·mL-1 of P. gingivalis within 30 s. Examination of periodontitis patients and healthy control saliva samples showed the potential of the assay. The simplicity and rapidity of the assay makes it an effective point-of-care device. Graphical abstract Schematic of the assay for the detection of P. gingivalis proteases as one of the promising biomarkers associated with periodontal diseases.

Highly Sensitive and Selective Colorimetric Detection of Methylmercury Based on DNA Functionalized Gold Nanoparticles.

A new colorimetric detection of methylmercury (CH3Hg⁺) was developed, which was based on the surface deposition of Hg enhancing the catalytic activity of gold nanoparticles (AuNPs). The AuNPs were functionalized with a specific DNA strand (HT7) recognizing CH3Hg⁺, which was used to capture and separate CH3Hg⁺ by centrifugation. It was found that the CH3Hg⁺ reduction resulted in the deposition of Hg onto the surface of AuNPs. As a result, the catalytic activity of the AuNPs toward the chromogenic reaction of 3,3,5,5-tetramethylbenzidine (TMB)-H2O2 was remarkably enhanced. Under optimal conditions, a limit of detection of 5.0 nM was obtained for CH3Hg⁺ with a linear range of 10⁻200 nM. We demonstrated that the colorimetric method was fairly simple with a low cost and can be conveniently applied to CH3Hg⁺ detection in environmental samples.

Characterising the variations in ethnic skin colours: a new calibrated data base for human skin.

BACKGROUND: Accurate skin colour measurements are important for numerous medical applications including the diagnosis and treatment of cutaneous disorders and the provision of maxillofacial soft tissue prostheses. METHODS: In this study, we obtained accurate skin colour measurements from four different ethnic groups (Caucasian, Chinese, Kurdish, Thai) and at four different body locations (Forehead, cheek, inner arm, back of hand) with a view of establishing a new skin colour database for medical and cosmetic applications. Skin colours are measured using a spectrophotometer and converted to a device-independent standard colour appearance space (CIELAB) where skin colour is expressed as values along the three dimensions: Lightness L*, Redness a* and Yellowness b*. Skin colour differences and variation are then evaluated as a function of ethnicity and body location. RESULTS: We report three main results: (1) When plotted in a standard colour appearance space (CIELAB), skin colour distributions for the four ethnic groups overlap significantly, although there are systematic mean differences. Between ethnicities, the most significant skin colour differences occur along the yellowness dimension, with Thai skin exhibiting the highest yellowness (b*) value and Caucasian skin the lowest value. Facial redness (a*) is invariant across the four ethnic groups. (2) Between different body locations, there are significant variations in redness (a*), with the forehead showing the highest redness value and the inner arm the lowest. (3) The colour gamut is smallest in the Chinese sample and largest in the Caucasian sample, with the Chinese gamut lying entirely the Caucasian gamut. Similarly, the largest variability in skin tones is found in the Caucasian group, and the smallest in the Chinese group. CONCLUSION: Broadly speaking, skin colour variation can be explained by two main factors: individual differences in lightness and yellowness are mostly due to ethnicity, whereas differences in redness are primarily due to different body locations. Variations in lightness are more idiosyncratic probably reflecting the large influence of environmental factors such as exposure to sun.

Identification of lysine K18 acetylation on histone H3 peptide using gold nanoparticles' aggregation behaviour.

Acetylation of histones, the major protein component of eukaryotic chromosomes, contributes to the epigenetic regulation of gene expression and is also involved in cancer development. A recent study revealed the correlation between tumour formation and acetylation level of lysine K18 on histone H3. In this study, we developed two colorimetric in vitro assays using gold nanoparticles (AuNPs) for identification of lysine K18 acetylation on histone H3 peptide. In assay I, citrate ion-capped AuNP without further modification was employed. Simply mixing the K18 peptide with AuNP solution leads to distinct particle aggregation, relative to that by non-acetylated or lysine K14 acetylated control peptides. In assay II, an AuNP-peptide-antibody composite was synthesized and used as both the sensing probe and the transducing element. By mixing the sample peptides with the composite solution followed by PBS screening, different aggregation behaviours were observed between the K18 acetylated target peptide and the control sequences. Both assays are capable of identifying the acetylated peptides, and also differentiating the distinctive acetylation positions that differ merely by a distance of three amino acids.

Objective measurement of erythema in psoriasis using digital color photography with color calibration.

BACKGROUND: Traditional metrics for evaluating the severity of psoriasis are subjective, which complicates efforts to measure effective treatments in clinical trials. METHODS: We collected images of psoriasis plaques and calibrated the coloration of the images according to an included color card. Features were extracted from the images and used to train a linear discriminant analysis classifier with cross-validation to automatically classify the degree of erythema. The results were tested against numerical scores obtained by a panel of dermatologists using a standard rating system. RESULTS: Quantitative measures of erythema based on the digital color images showed good agreement with subjective assessment of erythema severity (κ = 0.4203). The color calibration process improved the agreement from κ = 0.2364 to κ = 0.4203. CONCLUSION: We propose a method for the objective measurement of the psoriasis severity parameter of erythema and show that the calibration process improved the results.

Prehospital Endotracheal Intubation in Warm Climates: Caution is Required.

BACKGROUND: Out-of-hospital endotracheal intubation is a frequent procedure for trauma care. Nevertheless, in warm climates, sunlight and heat can interfere with the flow of the usual procedure. They can affect the equipment and hinder the operator. There are few data on this issue. The presentation of this case highlights three common complications that may occur when intubating under a hot and bright sun. CASE REPORT: A 23-year-old man had a car accident in Djibouti, at 11:00 a.m., in broad sunlight. The heat was scorching. Due to a severe head trauma, with a Glasgow Coma Scale score of 8, it was decided to perform an endotracheal intubation. The operator faced three problems: the difficulty of seeing inside the mouth in the bright sunlight, the softening of the tube under the influence of the heat, and the inefficiency of colorimetric CO2 detectors in the warm atmosphere in confirming the proper endotracheal tube placement. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Solutions are simple, but must be known and planned ahead, prior to beginning the procedure: Putting a jacket over his head while doing the laryngoscopy would solve the problem of dazzle; adjuncts like a stylet or gum elastic bougie have to be used at the outset to fix the softening problem; alternative methods to exhaled CO2 detection, such as the syringe aspiration technique, to confirm the proper tube placement, should be available.