Innovative model of surface-enhanced Raman spectroscopy for exosomes identification: An approach for the diagnosis of hepatocellular carcinoma

BACKGROUND

The current hepatocellular carcinoma (HCC) diagnostic approaches lack adequate sensitivity and specificity. So, this study was performed to develop an innovative model of surface-enhanced Raman spectroscopy (SERS) that can detect HCC patients by identifying the circulating tumor-derived exosomes.

METHODOLOGY

Sixty participants, including normal controls, hepatitis C virus (HCV)-infected patients, and HCV-associated HCC patients, had their whole blood samples and exosomes separated from these samples analyzed using Raman spectroscopy (RS). A revolutionary model of SERS, based on an innovative glass and nano-gold, was designed to directly identify exosomes. Its measurements were simulated by Comsol Multiphysics (5.6).

RESULTS

The RS examination of the whole blood samples revealed no Raman peaks. Yet, the isolated exosomes from these samples generated Raman peaks at 400 and 1000 cm^-1 wavenumbers in the HCV group. A Raman shift was detected in HCC patients at 812, 852, and 878 cm^-1 wavenumbers with intensity ratios of 120, 130, and 60, respectively. The RS had a sensitivity and specificity of 95 % and 100 %, respectively, for detecting HCC. However, the newly-designed SERS was able to identify the HCC-derived exosomes, at 812 and 878 cm^-1 wavenumbers, with boosted intensity ratios of 9*10⁶ and 4*10⁶, respectively, in the whole blood samples.

CONCLUSION

The newly-developed SERS model has the potential to detect HCC patients through recognizing the tumor-derived exosomes non-invasively, with high accuracy, and without the need for laborious exosomal separation. Nonetheless, bringing this technology into the clinic demands the establishment of spectral databases and their validation using the current gold standards.

Nano-gold-enhanced LAMP method for qualitative visual detection of Salmonella in milk

Since Salmonella can cause foodborne disease and public health safety issues and requires a robust, rapid, on-site detection method, a novel visual qualitative method with nano-gold-enhanced loop-mediated isothermal amplification (LAMP) reaction was established for detecting Salmonella in an integrated tube. During the experiment, nano-gold were used to enhance LAMP amplification, improving amplification efficiency and shortening the reaction time to within 30 min. Visual qualitative detection is achieved via negative staining, involving the addition of CuSO₄ to the final products of the LAMP reaction. Ring-like white accumulation occurs in the absence of Salmonella targets but not when they are present. After completing the LAMP reaction, the integration tube was shaken gently for 1 min to observe the liquid phase system changes, realizing the closed tube detection of Salmonella. The process resolved the challenge presented by cross-contamination, false positives, and nonspecific amplification during the LAMP reaction. This method was used to detect Salmonella in milk, further highlighting its prospects in the field of rapid food safety detection.

Colorimetric and fluorescent probes for the rapid detection of profenofos in farmland system

Colorimetric and fluorescent sensors were developed for the detection of profenofos. The colorimetric assay relied on the aggregation of cysteine modified gold nanoparticles (Au-cys) composite caused by the hydrogen bond and Au-S bond between profenofos and Au-cys. The further addition of S, N-doped carbon quantum dots (CDs) (fluorescence quantum yield up to 98%) into the Au-cys system depended on the change of fluorescence intensity of Au-cys-CDs owing to the inner filter effect between Au-cys and CDs. Under the optimal conditions, the sensor exhibits good linearity within 0.2-1.2 mg L^-1 and 20-320 μg L^-1, and limit of detection of 21.7 μg L^-1 and 5.5 μg L^-1 in colorimetry and fluorescence mode, respectively. The developed sensor did not only possess favorable selectivity and sensitivity, but also feasibility of usage in the actual detection of profenofos in farmland system samples.

Flavonoid-Decorated Nano-gold for Antimicrobial Therapy Against Gram-negative Bacteria Escherichia coli

Nano-gold (Aunps) have emerged as promising options that exhibit unique features discrete from traditional materials suited for biomedical applications. Aunps were synthesized using flavonoid quercetin (Q) as reducing agent, and resultant nanoparticles were further conjugated with the flavonoid. The resultant nano-system was expected to perform a dual role as antibacterial and as antioxidant agent. Nano-gold surface plasmon peaks were recorded at 560 nm with size around 62 nm and having slim distribution pattern. Spherical particle with smooth surface was observed under TEM and AFM studies. TEM micrographs confirmed a homogeneous particle population of size around 30 nm. Quercetin association to nano-gold was corroborated through FTIR and EDAX analysis. Antioxidant nature of nano-gold prevented rapid oxidation of brilliant cresyl blue dye, in presence of sodium hypochlorite. Antimicrobial action of QuAunp was tested against Gram-negative bacteria Escherichia coli. Nano-gold designed produced a minimum inhibitory concentration of 7.6 μg/ml and minimum bactericidal concentration 10.5 μg/ml against E. coli. Further TEM analysis and membrane permeability studies revealed the impact of QuAunps on bacterial membrane leading to cell damage.

Evaluation of immunotropic activity of gold nanocolloid in chickens

Gold nanoparticles (AuNPs) are one of the most examined nanomaterials, but information about their immunogenic potential is still insufficient. Understanding interaction of AuNPs with immune system is essential in designing their safety and possibilities of biomedical applications. An experiment was conducted to determine immunotropic activity of gold nanocolloid (AuNPs) administered orally to chickens depending on dose and duration time. 162 birds were assigned to 9 experimental groups of 18 birds each. The control group (C) did not receive AuNPs. Groups: T1_0.5, T1_1.0, T1_1.5, T1_2.0, received nano-gold in a rate of 0.5 mg/kg body weight/d, 1.0 mg/kg body weight/d, 1.5 mg/kg body weight/d and 2.0 mg/kg body weight/d in 8-14, 22-28 and 36-42 days of the life. The birds in groups T2_0.5, T2_1.0, T2_1.5, T2_2.0, received nano-gold in the same doses, but only in 8-10, 22-24 and 36-38 days of life. Phagocytic activity of leukocytes was determined in vitro using Staphylococcus aureus 209P strain, their respiratory burst activity was quantified by nitroblue tetrazolium reduction test. Serum lysozyme content was determined by the turbidimetric method. The Wintrobe method was used to determine the erythrocyte sedimentation rate. Ceruloplasmin in the blood plasma was estimated by the p-phenylenediamine colorimetric method. The level of chicken immunoglobulins: IgA, IgM and IgY and interleukin IL-6 in the blood were determined using ELISA tests. The lowest dose of AuNPs, independently on duration time had no effect on immune parameters of chickens. In all other groups receiving nano-gold for a shorter period (T2), there was an increase in the respiratory burst activity of leukocytes and a drop in lysozyme activity in blood. The higher doses (1.5 and 2.0 mg/kg body weight/d) of the nano-gold administered for the longer time period had a pro-inflammatory effect, as indicated by an increase in the level of interleukin 6 and ceruloplasmin activity as well as the erythrocyte sedimentation rate. They also contributed to an elevation of class IgA and IgY contents in blood. The results of the study revealed that the influence of nano-gold on immune response of chickens were dependent both on dose and duration time. Long lasting administration of higher doses of AuNPs contributed to adverse effect in form of inflammation response. To avoid the development of inflammatory reaction, administered dose of nano-gold should not exceed 1.0 mg/kg body weight/d.

Nanogold bioconjugates for direct and sensitive multiplexed immunosensing

The use of nanogold bioconjugates for direct detection of the antibody-antigen immunoreaction is addressed. The integration of gold nanoparticles tracers as signal generators in microarray immunosensing and compact disc detection technique show important advantages to reach sensitive, selective, high throughput, reliable and cost-effective assays. For that, a thorough study of the performances of the size of spherical nanogold particles and coating density was developed. The size of the nanoparticle determines the optimal antibody dilution, being the smaller particles the best performing ones. Enhancement effect of lower size is also studied. The gold labeling method do not affects the recognition capability of the labeled proteins. As a proof of concept, the nanoconjugates were used for the simultaneous and direct determination of small molecules. Employing nanogold bioconjugates as recognition labels resulted in robust and reliable assays, reaching a sensitivity of 0.03 and 1.3μg/L for sulfasalazine and atrazine, respectively. This shows that the use of nanogold bioconjugates for direct immunosensing is very competitive, achieving highly sensitive and reproducible assays (RSD<10%). This approach would simultaneously determine both small and large molecular size targets, in different formats, using the same detection mode what paves the way for many other applications in different scenarios.

Effect of gold nanoparticles and ciprofloxacin on microbial catabolism: a community-based approach

The effect of gold nanoparticles (AuNPs) and ciprofloxacin on the catabolism of microbial communities was assessed. This was accomplished through an ex situ methodology designed to give a priori knowledge on the potential for nanoparticles, or other emerging contaminants, to affect the catabolic capabilities of microbial communities in the environment. Microbial communities from a variety of sources were incubated with 31 prespecified carbon sources and either National Institute of Standards and Technology reference material 10-nm AuNPs or ciprofloxacin on 96-well microtiter plates. From the ciprofloxacin study, dose-response curves were generated and exemplified how this method can be used to assess the effect of a toxicant on overall catabolic capabilities of microbial communities. With 10-nm AuNPs at concentrations ranging from 0.01 µg/mL to 0.5 µg/mL, rhizosphere communities from Typha roots were only slightly catabolically inhibited at a single concentration (0.05 µg/mL); no effects were seen on wetland water communities, and a minor positive (i.e., enhanced catabolic capabilities) effect was observed for loamy soil communities. This positive effect might have been because of a thin layer of citrate found on these AuNPs that initiated cometabolism with some of the carbon sources studied. Under the conditions considered, the possible adverse effects of AuNPs on the catabolic capabilities of microbial communities appears to be minimal.

Following the Behavior of the Flagellar Rotary Motor Near Zero Load

At room temperature at stall, the flagellar motor of the bacterium Escherichia coli exerts a torque of ~1300 pN nm. At zero external load, it spins ~330 Hz. A robust method for studying the motor near zero load is reviewed here.