Vibrational spectroscopic techniques can detect small variations in molecular content, linked with disease, showing promise for screening and early diagnosis. Biological fluids, particularly blood serum, are potentially valuable for diagnosis purposes. The so-called Low Molecular Weight Fraction (LMWF) contains the associated peptidome and metabolome and has been identified as potentially the most relevant molecular population for disease-associated biomarker research. Although vibrational spectroscopy can deliver a specific chemical fingerprint of the samples, the High Molecular Weight Fraction (HMWF), composed of the most abundant serum proteins, strongly dominates the response and ultimately makes the detection of minor spectral variations a challenging task. Spectroscopic detection of potential serum biomarkers present at relatively low concentrations can be improved using pre-analytical depletion of the HMWF. In the present study, human serum fractionation by centrifugal filtration was used prior to analysis by Attenuated Total Reflection infrared spectroscopy. Using a model sample based on glycine spiked serum, it is demonstrated that the screening of the LMWF can be applied to quantify blinded concentrations up to 50 times lower. Moreover, the approach is easily transferable to different bodily fluids which would support the development of more efficient and suitable clinical protocols exploring vibrational spectroscopy based ex-vivo diagnostic tools

Fungi, which are common in the environment, can cause a multitude of diseases. Warm, humid conditions allow fungi to grow and infect humans via the respiratory, digestive and reproductive tracts, genital area and other bodily interfaces. Fungi can be detected directly by microscopy, using the potassium hydroxide test, which is the gold standard and most popular method for fungal screening. However, this test requires trained personnel operating specialist equipment, including a fluorescent microscope and culture facilities. As most acutely infected patients seek medical attention within the first few days of symptoms, the optimal diagnostic test would be rapid and self-diagnostic simplifying and improving the therapeutic outcome. In suspensions of gold nanoparticles, Aspergillus niger can cause a colour change from red to blue within 2 min, as a result of changes in nanoparticle shape. A similar colour change was observed in the supernatant of samples of human toenails dispersed in water. Scanning electron microscopy, UV/Vis and Raman spectroscopy were employed to monitor the changes in morphology and surface plasmon resonance of the nanoparticles. The correlation of colour change with the fungal infection was analysed using the absorbance ratio at 520 nm/620 nm. We found a decrease in the ratio when the fungi concentration increased from 1 to 16 CFU/mL, with a detection limit of 10 CFU/mL. The test had an 80% sensitivity and a 95% specificity value for the diagnosis of athlete's foot in human patients. This plasmonic gold nanoparticle-based system for detection of fungal infections measures the change in shape of gold nanoparticles and generates coloured solutions with distinct tonality. Our application has the potential to contribute to self-diagnosis and hygiene control in laboratories/hospitals with fewer resources, just using the naked eye. Graphical abstract Colorimetric method for fungi detection with gold nano particles.

Lateral flow immunochromatographic assays are a powerful diagnostic tool for point-of-care tests, based on their simplicity, specificity, and sensitivity. In this study, a rapid and sensitive gold nanoparticle (AuNP) immunochromatographic strip is produced for detecting aflatoxin B1 (AFB1) in suspicious fungi-contaminated food samples. The 10 nm AuNPs were encompassed by bovine serum albumin (BSA) and AFB1 antibody. Thin-layer chromatography, gel electrophoresis and nuclear magnetic resonance spectroscopy were employed for analysing the chemical complexes. Various concentrations of AFB1 antigen (0-16 ng/mL) were tested with AFB1 antibody-BSA-AuNPs (conjugated AuNPs) and then analysed by scanning electron microscopy, ultraviolet-visible spectroscopy, and Zetasizer. The results showed that the AFB1 antibody was coupled to BSA by the N-hydroxysuccinimide ester method. The AuNPs application has the potential to contribute to AFB1 detection by monitoring a visible colour change from red to purple-blue, with a detection limit of 2 ng/mL in a 96-well plate. The lateral flow immunochromatographic strip tests are rapid, taking less than 10 min., and they have a detection capacity of 10 ng/g. The smartphone analysis of strips provided the results in 3 s, with a detection limit of 0.3 ng/g for AFB1 when the concentration was below 10 ng/g. Excellent agreement was found with AFB1 determination by high-performance liquid chromatography in the determination of AFB1 among 20 samples of peanuts, corn, rice, and bread.for Aflatoixin B1 (AFB1) [8]. The European Economic Community (EEC) has established permitted food contamination limits of 2 µg/kg for AFB1 and 4 µg/kg for the total concentration of the four AFLs since 1 February 1999 [9]. Therefore, it is necessary to develop strategies for achieving the limits of AFL contamination and reducing AFL exposure in vulnerable populations [10].Thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) are the most popular techniques for detecting AFLs. However, these methods require extensive sample preparation, expensive instruments, and operation by skilled professionals. Alternatively, the enzyme-linked immunosorbent assay (ELISA) has been successfully developed for AFLs [11], but ELISA also needs incubation and washing steps, and application is mainly confined to laboratories. Lateral flow immunochromatographic/immunoassay strips (LFIAs) have received increasing attention for qualitative and quantitative analysis in different scientific sectors [12], including food safety, environmental monitoring, and precision medicine [12,13]. In 2005, Delmulle et al. [14] developed an LFIA for the detection of aflatoxin B1 (AFB1) in pig feed. Liao and Li [15] have made significant effort to investigate the effect of the core-shell silver-gold nanocomposites on the properties of LFIAs. However, this detection can only provide either qualitative (positive or negative) or semi-quantitative information on analyte concentration, and thereby does not satisfy the requirements for...

To investigate the influence of starvation on the biochemical response of Aspergillus niger. The biochemical impact of starvation was determined by morphological observation, immunofluorescent analysis, High-performance liquid chromatography (HPLC) and western blot over 8 days. Results showed that starvation can inhibit fungi survival rate in a time-dependent manner. A. niger exhibited active responses to starvation such as secretion of some 40 kDa proteins to manage changes in water balance. Conidiophores disintegrated from lack of nutrient. The immunofluorescent analysis demonstrated elevated ROS accumulation in starved cells (P<0.001). The fluorescent microscopy of the TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labelling) staining showed positive in the starved fungi. The mitochondrial stains revealed that the fluorescence emitted by the normal fungi was higher than the starving ones. Western blot analysis showed that starvation can induce up-regulation expression of cell cycle-associated proteins such as PKA, Caspase 1 and Heat Shock Protein 40 (HSP40). These results suggest that up regulation of apoptosis-associated protein may contribute to fungi apoptosis. In conclusion, starvations can active PKA, Caspase 1 and HSP40 protein to inhibit A. niger growth by inducing cell apoptosis.