Differential Interaction of Metal Ions with Gold Nanoclusters and Application in Detection of Cobalt and Cadmium

Interest in biosensing platforms using protein fluorescent gold nanoclusters (FGNCs) has grown significantly in the past due to the unique optical properties they offer. This study investigates the interaction of metal ions with FGNCs, and the structural modifications brought about by the interaction resulting in fluorescence changes of the cluster and its successful application in the detection of two heavy metals, cobalt and cadmium. The binding of cobalt and cadmium to FGNCs synthesized from BSA significantly altered the secondary structure of the protein, causing a change in its hydrophobicity. It also resulted in a change in fluorescence properties of FGNCs by intersystem crossing (ICT) and fluorescence resonance energy transfer (FRET). Cobalt and cadmium could successfully be detected in the range of 5-165 ng/mL (R² = 0.95) and 20-1000 ng/ mL (R² = 0.91), respectively, with appreciable sensitivity. The principle was also applied for the detection of Vitamin B₁₂ in commercially available ampoules, validating the proposed method. Graphical Abstract Proposed detection method of cadmium and cobalt using FGNCs.

Aptamer as capture agent in enzyme-linked apta-sorbent assay (ELASA) for ultrasensitive detection of Aflatoxin B1

Aflatoxin B₁ (AFB₁), is one of the most toxic mycotoxins found to contaminate various food commodities like cereals, dried fruits, tree nuts, spices and crude vegetable oils. In spite of considerable progress in analytical techniques, there is still a need to develop rapid and highly sensitive detection platforms for AFB₁. In this study, AFB₁ specific aptamer was used as a capture molecule to develop an enzyme-linked apta-sorbent assay (ELASA) for ultrasensitive detection of AFB₁. Under optimized conditions, the assay had a linear detection range from 1 μg to 1 pg with a limit of detection (LOD) of 1 pg/mL in buffer. Conventional ELISA with AFB₁ hapten as the capture agent (LOD = 10 pg/mL) was also carried out to compare the results with the present method. Recovery studies in food samples like dried red chillies, groundnut and pepper using both the methods was found to be in the range of 88.49-106.4% at 10 ng/mL and 87.4% to 95.8% at 5 ng/mL for ELASA and 76.56-127.68% at 10 ng/mL and 82-101.2% at 5 ng/mL for ELISA. Higher detection (10 fold) and better recovery using ELASA suggest that the method could offer an early, ultrasensitive, high-throughput, qualitative and semi-quantitative detection of AFB₁ in contaminated food samples.

Antiaflatoxigenic and Antimicrobial Activities of Schiff Bases of 2-Hydroxy-4-methoxybenzaldehyde, Cinnamaldehyde, and Similar Aldehydes

2-Hydroxy-4-methoxybenzaldehyde (HMBA) is a nontoxic phenolic flavor from dietary source Decalipus hamiltonii and Hemidesmus indicus. HMBA is an excellent antimicrobial agent with additional antiaflatoxigenic potency. On the other hand, cinnamaldehyde from cinnamon is a widely employed flavor with significant antiaflatoxigenic activity. We have attempted the enhancement of antiaflatoxigenic and antimicrobial properties of HMBA, cinnamaldehyde, and similar molecules via Schiff base formation accomplished from condensation reaction with amino sugar (d-glucamine). HMBA derived Schiff bases exhibited commendable antiaflatoxigenic activity at the concentration 0.1 mg/mL resulting in 9.6 ± 1.9% growth of Aspergillus flavus and subsequent 91.4 ± 3.9% reduction of aflatoxin B₁ with respect to control.

Fluorescent competitive aptasensor for detection of aflatoxin B1

Aflatoxin B1 (AFB₁ ) is one of the most commonly found mycotoxins in food commodities, particularly cereals, oilseeds, spices and tree nuts. In the past decade, aptamers have come into limelight and emerged as a new biosensing element replacing antibodies in various detection formats. Herein we report a faster, more sensitive, high throughput method for the detection of AFB₁ using AFB₁ -specific aptamers. The assay format was based on a competitive reaction of the fluorescent tagged aptamer specific to AFB₁ with the aflatoxin conjugate. Under optimal conditions, a linear range of detection (50 ng to 50 pg) was achieved with a limit of detection (LOD) of 10 pg/mL in the buffer system. Results of inter- and intra-assay revealed that the assay was repeatable with standard deviation in acceptable range. The assay was also validated in food samples such as dried red chilies, groundnut and whole pepper with recovery in the range of 92 to 102% at 10 ng/mL and 100 pg/mL levels. The aptasensor assay was also compared with standard analytical method of HPLC and was found to be more sensitive. This detection technique has the potential to be developed into a biosensor platform for AFB₁ detection.

Expeditious Synthesis, Antimicrobial and Antimalarial Activities of Novel Heterocycles Bearing Imidazole-oxadiazole Based Hybrid Pharmacophores

A facile synthesis of 2-substituted-5-amino-oxadiazole derivatives has been achieved by refluxing/sonicating a mixture of semicarbazide with various aromatic acids in conc. sulphuric acid alone. The isolated products were further condensed with p-dimethylaminobenzaldehyde/p-hydroxybenzaldehyde to obtain respective imino derivatives. Finally, some potentially biologically active imidazole analogues were obtained by reacting ammonium acetate and 5-bromoisatin with the synthesized imino products. All the newly synthesized compounds were thoroughly characterized by standard analytical techniques. These imidazole-oxadiazole hybrid compounds were also evaluated for their antimicrobial and antimalarial activities. The compounds all exhibited moderate to significant antimicrobial activity (6-10 mm, zone of inhibition) and promising antimalarial activity (IC₅₀ 0.037-0.100 µM). This report entails a detailed synthetic procedure, spectroscopic elucidation and activities of the synthesized compounds.

Tunneling of redox enzymes to design nano-probes for monitoring NAD(+) dependent bio-catalytic activity

Monitoring of bio-catalytic events by using nano-probes is of immense interest due to unique optical properties of metal nanoparticles. In the present study, tunneling of enzyme activity was achieved using redox cofactors namely oxidized cytochrome-c (Cyt-c) and Co-enzyme-Q (Co-Q) immobilized on Quantum dots (QDs) which acted as a bio-probe for NAD(+) dependent dehydrogenase catalyzed reaction. We studied how electron transfer from substrate to non-native electron acceptors can differentially modify photoluminescence properties of CdTe QDs. Two probes were designed, QD-Ox-Cyt-c and QD-Ox-Co-Q, which were found to quench the fluorescence of QDs. However, formaldehyde dehydrogenase (FDH) catalyzed reduction of Cyt-c and Co-Q on the surface of QDs lead to fluorescence turn-on of CdTe QDs. This phenomenon was successfully used for the detection of HCHO in the range of 0.01-100,000ng/mL (LOD of 0.01ng/mL) using both QD-Ox-Cyt-c (R(2)=0.93) and QD-Ox-Co-Q (R(2)=0.96). Further probe performance and stability in samples like milk, wine and fruit juice matrix were studied and we could detect HCHO in range of 0.001-100,000ng/mL (LOD of 0.001ng/mL) with good stability and sensitivity of probe in real samples (R(2)=0.97). Appreciable recovery and detection sensitivity in the presence of metal ions suggests that the developed nano-probes can be used successfully for monitoring dehydrogenase based bio-catalytic events even in the absence of NAD(+). Proposed method is advantageous over classical methods as clean up/ derivatization of samples is not required for formaldehyde detection.

Gold nanoparticle synthesis coupled to fluorescence turn-on for sensitive detection of formaldehyde using formaldehyde dehydrogenase

Ultrasensitive detection of formaldehyde by coupling enzyme activity with GNP synthesis.

Plectranthus amboinicus leaves stimulate growth of probiotic L. plantarum: evidence for ethnobotanical use in diarrhea

ETHNOPHARMACOLOGICAL RELEVANCE

Leaves of Plectranthus amboinicus are consumed in India along with buttermilk (a probiotic source) during pathogen induced diarrhea. This treatment is known to reduce the number of episodes as well as duration of diarrhea.

AIM OF THE STUDY

In the background of its ethnobotanical use, the present investigation was carried out to determine whether, apart from having an antimicrobial activity on pathogens, the leaves could possibly also have a positive effect on the beneficial microflora of the gut resulting in accelerated microbial ecological balance.

MATERIALS AND METHODS

The growth stimulating activity of the hot water extract (HWE) of P. amboinicus leaves on probiotic Lactobacillus plantarum was determined by microbroth dilution technique and viable plate count method in selective medium (MRS) as well as in fermented milk. The ability of the bacteria to utilize the phytoconstituents of HWE primarily phenolic acids and sugars was determined by assaying for phenolic acid decarboxylase by SDS-PAGE and β-galactosidase activity by β-gal ONPG assay.

RESULTS

HWE of P. amboinicus leaves inhibited growth of pathogens (Escherichia coli and Salmonella typhimurium) while stimulated the growth of L. plantarum. SDS-PAGE gel showed the presence of phenolic acid decarboxylase enzyme induced in the presence of HWE in L. plantarum indicating the utilization of polyphenols by the bacteria. Cells grown on HWE also showed β-galactosidase activity indicating their ability to utilize sugars present in HWE.

CONCLUSION

Indian borage leaves have a prebiotic effect on the probiotic bacteria (L. plantarum) which utilizes the phytoconstituents of the leaves by producing necessary metabolic enzymes. This work provides evidence in the traditional use of the leaves in the alleviation of diarrhea by accelerating microbial gut balance during infection.

Inhibition of LDL oxidation and oxidized LDL-induced foam cell formation in RAW 264.7 cells show anti-atherogenic properties of a foliar methanol extract of Scoparia dulcis

Background:

Oxidation of low density lipoproteins and their further uptake by macrophages is known to result in the formation of foam cells, which are critical in the initiation of atherosclerosis through activation of inflammatory signalling cascades. Thus, powerful dietary antioxidants are receiving attention for the reversal of such pathological states.

Materials and Methods:

Extracts of Scoparia dulcis have been used as tea and health drinks with various health promoting effects. In the present study, we examined the reactive oxygen scavenging potential as well as anti-inflammatory and anti-atherogenic efficacies, using leaf extracts obtained after successive extraction with various solvents.

Results:

A methanol extract showed potent antioxidant activity with an IC₅₀ value of 570 μg/ml, caused hydrogen peroxide scavenging (28.9 µg/ml) and anti-inflammatory effects by improving human erythrocyte membrane stabilisation (about 86%). The methanol extract also efficiently inhibited lipid peroxidation and oxidation of low density lipoproteins, thus preventing foam cell formation in cultured RAW 264.7 cells. Furthermore, phytochemical screening of the extracts showed high accumulation of flavonoids.

Conclusions:

The foliar methanol extract of Scoparia dulcis has a strong anti-atherogenic potential and this property could be attributed maybe due to presence of flavonoids since HPLC analysis showed high concentrations of myricetin and rutin in the methanol extract.

In vitro vancomycin susceptibility amongst methicillin resistant Staphylococcus aureus

BACKGROUND

Vancomycin is drug of choice for treatment of Methicillin Resistant Staphylococcus aureus (MRSA) infections. S. aureus with reduced vancomycin susceptibility (SA-RVS) is on rise. Current guidelines of detection of SA-RVS are based on MIC (Minimum Inhibitory Concentration) by broth or agar dilution methods. Vancomycin MIC by E test (Epsilometer Test) is an alternative. A study was undertaken to know the prevalence of SA-RVS and compare vancomycin MIC by agar dilution and E test.

METHODS

A prospective study was undertaken at tertiary care hospital; 232 clinical MRSA isolates were included. Vancomycin MIC was undertaken by agar dilution method and E test.

RESULTS

All isolates were sensitive to Linezolid. Two MRSA isolates had vancomycin MIC ≥4 μg/ml; vancomycin MIC50 and MIC90 of MRSA isolates was 0.5 and 0.2 μg/ml respectively by agar dilution method. There was agreement over 93.5% isolates in vancomycin susceptibility by agar dilution and E test. E test had sensitivity and positive predictive value of 1.0 (CI - 0.34-1.0) and 0.5 (CI - 0.17-0.83) respectively compare to agar dilution method.

CONCLUSIONS

MRSA isolates continues to be susceptible to vancomycin and Linezolid. E test was found equally suitable in initial screening for vancomycin susceptibility. Due to geographic variation in prevalence, there is need of ongoing surveillance of SA-RVC.

Molecular detection and epidemiology of chicken infectious anaemia virus in India

Chicken infectious anemia (CIA) is an economically important disease affecting poultry, especially young chicks, characterized by poor weight gain, anemia, immunosuppression and production losses. Recent reports indicate that the virus is emerging and re-emerging worldwide.  Also, scarce reports regarding the molecular detection and epidemiology of virus from India are available. The aim of this study was to determine the prevalence of the virus in the commercial poultry farms of the country employing polymerase chain reaction (PCR). Out of the suspected 424 field samples tested from 12 different states of the country during the last five years (2007-2012), 311 (73.3%) samples were found positive for CIAV-DNA indicating the wide prevalence of the virus in India. The age wise prevalence of the virus indicated high prevalence in young chicks of up to three weeks (80.3%) of age compared to 3-7 (66.6%) and 7-12 (25%) week age groups. Being an immunosuppressive emerging pathogen circulating among the poultry flocks of the country, suitable prevention and control measures need to be adopted timely. This is a first elaborative report on the molecular epidemiology of CIAV in poultry flocks of the country. Extensive epidemiological studies are suggested to know the magnitude of the virus affecting poultry industry of the country, and design and formulate effective disease prevention and control strategies to reduce economic losses being caused by emerging virus.

Survival analysis of patients with high-grade gliomas based on data mining of imaging variables

BACKGROUND AND PURPOSE

The prediction of prognosis in HGGs is poor in the majority of patients. Our aim was to test whether multivariate prediction models constructed by machine-learning methods provide a more accurate predictor of prognosis in HGGs than histopathologic classification. The prediction of survival was based on DTI and rCBV measurements as an adjunct to conventional imaging.

MATERIALS AND METHODS

The relationship of survival to 55 variables, including clinical parameters (age, sex), categoric or continuous tumor descriptors (eg, tumor location, extent of resection, multifocality, edema), and imaging characteristics in ROIs, was analyzed in a multivariate fashion by using data-mining techniques. A variable selection method was applied to identify the overall most important variables. The analysis was performed on 74 HGGs (18 anaplastic gliomas WHO grades III/IV and 56 GBMs or gliosarcomas WHO grades IV/IV).

RESULTS

Five variables were identified as the most significant, including the extent of resection, mass effect, volume of enhancing tumor, maximum B0 intensity, and mean trace intensity in the nonenhancing/edematous region. These variables were used to construct a prediction model based on a J48 classification tree. The average classification accuracy, assessed by cross-validation, was 85.1%. Kaplan-Meier survival curves showed that the constructed prediction model classified malignant gliomas in a manner that better correlates with clinical outcome than standard histopathology.

CONCLUSIONS

Prediction models based on data-mining algorithms can provide a more accurate predictor of prognosis in malignant gliomas than histopathologic classification alone.