Smartphone-based surface plasmon resonance sensing platform for rapid detection of bacteria.

Bacterial infection poses severe threats to public health, and early rapid detection of the pathogen is critical for controlling bacterial infectious diseases. Current methods are commonly labor intensive, time consuming or dependent on lab-based equipment. In this study, we proposed a novel and practical method for bacterial detection based on smartphones using the surface plasmon resonance (SPR) phenomena of gold nanoparticles (AuNPs). The proposed smartphone-based SPR sensing method is achieved by utilizing color development that arises from the change in interparticle distance of AuNPs induced by bacterial lysate. The pictures of bacteria/AuNPs color development were captured, and their color signals were acquired through a commercial smartphone. The proposed method has a detection range between 2.44 × 105 and 1.25 × 108 cfu mL-1 and a detection limit of 8.81 × 104 cfu mL-1. Furthermore, this method has acceptable recoveries (between 85.7% and 95.4%) when measuring spiked real waters. Combining smartphone-based signal reading with AuNP-dependent color development also offers the following advantages: easy-to-use, real-time detection, free of complex equipment and low cost. In view of these features, this sensing platform would have widespread applications in the fields of medical, food, and environmental sciences.

Rapid measurement of waterborne bacterial viability based on difunctional gold nanoprobe.

Rapid measurement of waterborne bacterial viability is crucial for ensuring the safety of public health. Herein, we proposed a colorimetric assay for rapid measurement of waterborne bacterial viability based on a difunctional gold nanoprobe (dGNP). This versatile dGNP is composed of bacteria recognizing parts and signal indicating parts, and can generate color signals while recognizing bacterial suspensions of different viabilities. This dGNP-based colorimetric assay has a fast response and can be accomplished within 10 min. Moreover, the proposed colorimetric method is able to measure bacterial viability between 0% and 100%. The method can also measure the viability of other bacteria including Staphylococcus aureus, Shewanella oneidensis, and Escherichia coli O157H7. Furthermore, the proposed method has acceptable recovery (95.5-104.5%) in measuring bacteria-spiked real samples. This study offers a simple and effective method for the rapid measurement of bacterial viability and therefore should have application potential in medical diagnosis, food safety, and environmental monitoring.

In situ detection of microbial c-type cytochrome based on intrinsic peroxidase-like activity using screen-printed carbon electrode.

C-type cytochromes (c-cyts) facilitate microbial extracellular electron transfer and play critical roles in biogeochemical cycling, bioelectricity generation and bioremediation. In this study, a simple and effective method has been developed to detect microbial c-cyts by means of peroxidase mimetic reaction on screen-printed carbon electrode (SPCE). To this end, bacteria cells were immobilized onto the working electrode surface of SPCE by a simple drop casting. After introducing 3,3',5,5'-tetramethylbenzidine (TMB) solution, microbial c-cyts with peroxidase-like activity catalyze the oxidation of TMB in the presence of hydrogen peroxide. The oxidized TMB was electrochemically determined and the current signal was employed to calculate the c-cyts content. This electrochemical method is highly sensitive for microbial c-cyts with a low detection limit of 40.78 fmol and a wide detection range between 51.70 fmol and 6.64 pmol. Moreover, the proposed technique can be universally expanded to detect c-cyts in other bacteria species such as Fontibacter ferrireducens, Pseudomonas aeruginosa, Comamonas guangdongensis and Escherichia coli. Furthermore, the proposed method confers an in situ facile and quantitative c-cyts detection without any destructive sample preparations, complex electrode modifications and expensive enzyme- or metal particle- based signal amplification. The suggested method advances an intelligent strategy for in situ quantification of microbial c-cyts and consequently holds promising application potential in microbiology and environmental science.

Preparation and characterization of egg yolk immunoglobulin Y specific to influenza B virus.

The aim of this study was to prepare egg yolk immunoglobulin (IgY) for use in the prevention and treatment of influenza B viral infections. Laying hens were immunized with inactivated influenza B virus (IBV), and IgY was isolated from the egg yolk by multiple polyethylene glycol (PEG) 6000 extraction and ammonium sulfate purification steps. The titers and specificity of the purified antibodies were assessed. The specific IgY titer increased beginning the second week after the first immunization, with the titer peaking at the fifth week. The yield of IgY was 76.5mg per yolk, and the purity was 98.2%. The use of western blotting and the hemagglutination inhibition (HI) test demonstrated that IBV-specific IgY binds specifically to influenza B virus proteins, and a plaque reduction assay revealed the neutralization efficacy of IBV-specific IgY at reducing influenza infection in MDCK cells. Furthermore, when mice were treated intranasally prior to or after influenza B virus infection, IBV-specific IgY protected the mice from influenza infection or reduced viral replication in their lungs, respectively. These findings indicate that IgY is an easily prepared and rich source of antibodies that offers a potential alternative strategy for preventing and treating influenza B infections.