Suresh Neethirajan

Nanotechnology for the Food and Bioprocessing Industries

Several complex set of engineering and scientific challenges in the food and bioprocessing industries for manufacturing high quality and safe food through efficient and sustainable means can be solved through nanotechnology. Bacteria identification and food quality monitoring using biosensors; intelligent, active, and smart food packaging systems; and nanoencapsulation of bioactive food compounds are few examples of emerging applications of nanotechnology for the food industry. We review the background about the potential of nanotechnology, provide an overview of the current and future applications of nanotechnology relevant to food and bioprocessing industry, and identify the societal implications for successful implementation of nanotechnology.

A novel microfluidic wound model for testing antimicrobial agents against Staphylococcus pseudintermedius biofilms

BackgroundCurrent methods for testing treatments for veterinary surgical site infections can successfully emulate elements of a chronic wound, but these are time consuming and costly, requiring specialized laboratory equipment and considerable space to house study animals. Microfluidic devices however, can be coated with collagen and maintained at basal body temperature, providing a more cost-effective and space-saving model of a chronic wound. Our study assesses the applicability of a new microfluidic model by testing the activity of DispersinB against biofilms of methicillin-resistant Staphylococcus pseudintermedius (MRSP); DispersinB has been shown to prevent biofilm growth of Staphylococcus epidermidis, another prominent wound colonizer.ResultsWe successfully developed a microfluidic model to examine the effects of antimicrobial therapy on biofilms formed by organisms associated with wound infections in companion animals (e.g. MRSP). Although, we were unable to recapitulate previous findings that DispersinB-Gentamycin is highly effective against Staphylococcal biofilms using this model, we were able to confirm its effect in a microtitre plate. Differences in the experimental conditions likely account for this result (e.g. strains tested, flow conditions, treatment time, etc.). In the microtitre plate assay, DispersinB inhibited biofilm growth after a 24 hour period; there was an inverse relationship between the concentration of DispersinB-Gentamycin and the amount of biofilm remaining following treatment. Collagen-coated microtitre plates showed a similar result, but this did not correlate as well; collagen, the most abundant protein in the body may help to retain the biomass of treated biofilms.ConclusionsOur model may be useful in examining the effect of treatment on wound infections, although we acknowledge that in this model the test organisms may be more recalcitrant to antimicrobials than in other published systems. We contend that this may in fact better represent the conditions in vivo, where organisms associated with chronic wound infections are highly resistant to antimicrobials.

Potential of silica bodies (phytoliths) for nanotechnology

Many plant systems accumulate silica in solid form, creating intracellular or extracellular silica bodies (phytoliths) that are essential for growth, mechanical strength, rigidity, predator and fungal defence, stiffness and cooling. Silica is an inorganic amorphous oxide formed by polymerization processes within plants. There has been much research to gain new insights into its biochemistry and to mimic biosilicification. We review the background on plant silica bodies, silica uptake mechanisms and applications, and suggest possible ways of producing plant silica bodies with new functions. Silica bodies offer complementary properties to diatoms for nanotechnology, including large-scale availability from crop wastes, lack of organic impurities (in some), microencapsulation and microcrystalline quartz with possibly unique optical properties.

Biosensors for the Detection of Antibiotics in Poultry Industry—A Review

Antibiotic resistance is emerging as a potential threat in the next decades. This is a global phenomenon whereby globalization is acting as a catalyst. Presently, the most common techniques used for the detection of antibiotics are biosensors, ELISA and liquid chromatography—mass spectrometry. Each of these techniques has its benefits as well as drawbacks. This review aims to evaluate different biosensing techniques and their working principles in order to accurately, quickly and practically detect antibiotics in chicken muscle and blood serum. The review is divided into three main sections, namely: a biosensors overview, a section on biosensor recognition and a section on biosensor transducing elements. The first segment provides a detailed overview on the different techniques available and their respective advantages and disadvantages. The second section consists of an evaluation of several analyte systems and their mechanisms. The last section of this review studies the working principles of biosensing transducing elements, focusing mainly on surface plasmon resonance (SPR) technology and its applications in industries.Antibiotic resistance is emerging as a potential threat in the next decades. This is a global phenomenon whereby globalization is acting as a catalyst. Presently, the most common techniques used for the detection of antibiotics are biosensors, ELISA and liquid chromatography-mass spectrometry. Each of these techniques has its benefits as well as drawbacks. This review aims to evaluate different biosensing techniques and their working principles in order to accurately, quickly and practically detect antibiotics in chicken muscle and blood serum. The review is divided into three main sections, namely: a biosensors overview, a section on biosensor recognition and a section on biosensor transducing elements. The first segment provides a detailed overview on the different techniques available and their respective advantages and disadvantages. The second section consists of an evaluation of several analyte systems and their mechanisms. The last section of this review studies the working principles of biosensing transducing elements, focusing mainly on surface plasmon resonance (SPR) technology and its applications in industries.

Efficacy of clarithromycin on biofilm formation of methicillin-resistant Staphylococcus pseudintermedius.

A bstractBackgroundSurgical site infections (SSIs) caused by biofilm-forming methicillin-resistant Staphylococcus pseudintermedius (MRSP) have emerged as the most common hospital-acquired infections in companion animals. No methods currently exist for the therapeutic remediation of SSIs caused by MRSP in biofilms. Clarithromycin (CLA) has been shown to prevent biofilm formation by Staphylococcus aureus. This study aims to assess the in vitro activity of CLA in eradicating MRSP biofilm formation on various materials.ResultsQuantitative assay results (P = 0.5126) suggest that CLA does not eradicate MRSP biofilm formation on polystyrene after 4 – 24 h growth periods. Scanning electron micrographs confirmed that CLA did not eradicate MRSP biofilm formed on orthopaedic implants.ConclusionsBy determining the in vitro characteristics and activities of MRSP isolates alone and against antibiotics, in vitro models of biofilm related infections can be made. In vitro data suggests that CLA does not effectively eradicate S. pseudintermedius biofilms in therapeutic doses.

Graphene oxide chemically decorated with Ag–Ru/chitosan nanoparticles: fabrication, electrode processing and immunosensing properties

Nanosheets of graphene oxide were chemically decorated with hybrid nanoparticles of a silver–ruthenium bipyridine complex (Ag@[Ru(bpy)3]2+) core and chitosan shell. The oxygenated groups of graphene oxide and the abundant amine groups in the chitosan layer on the surface of the hybrid nanoparticles allow functionalization reactions to occur. Changes in the optical, chemical and structural properties of graphene oxide occurred because the hybrid nanoparticles were studied using spectroscopy and microscopic techniques. Electrodes modified with hybrid nanoparticles-graphene oxide (HNPs-GO) displayed amplified steady-state anodic (IpA) and cathodic (IpC) peak currents with correlation coefficients of 0.9987 (IpA1), 0.9952 (IpA2) and 0.9964 (IpC1). Using the monoclonal antibody Listeria monocytogenes, a HNPs-GO immunosensor could specifically detect L. monocytogenes contaminated in buffer and milk, with a concentration range from 102 to 107 cells per mL and detection limit of 2 cells per mL. Our results suggest that selective optimization of the bio-recognition elements on the HNPs-GO electrode may find prospective use in food processing industries.

Rapid Detection of Food Allergens by Microfluidics ELISA-Based Optical Sensor.

The risks associated with the presence of hidden allergens in food have increased the need for rapid, sensitive, and reliable methods for tracing food allergens in commodities. Conventional enzyme immunosorbent assay (ELISA) has usually been performed in a centralized lab, requiring considerable time and sample/reagent consumption and expensive detection instruments. In this study, a microfluidic ELISA platform combined with a custom-designed optical sensor was developed for the quantitative analysis of the proteins wheat gluten and Ara h 1. The developed microfluidic ELISA biosensor reduced the total assay time from hours (up to 3.5 h) to 15–20 min and decreased sample/reagent consumption to 5–10 μL, compared to a few hundred microliters in commercial ELISA kits, with superior sensitivity. The quantitative capability of the presented biosensor is a distinctive advantage over the commercially available rapid methods such as lateral flow devices (LFD) and dipstick tests. The developed microfluidic biosensor demonstrates the potential for sensitive and less-expensive on-site determination for rapidly detecting food allergens in a complex sample system.

Collagen and hyaluronan at wound sites influence early polymicrobial biofilm adhesive events

BackgroundWounds can easily become chronically infected, leading to secondary health complications, which occur more frequently in individuals with diabetes, compromised immune systems, and those that have suffered severe burns. When wounds become chronically infected, biofilm producing microbes are often isolated from these sites. The presence of a biofilm at a wound site has significant negative impact on the treatment outcomes, as biofilms are characteristically recalcitrant to removal, in part due to the formation of a protective matrix that shield residents organisms from inimical forces. Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA) are two of the organisms most prevalently isolated from wound sites, and are of particular concern due to their elevated levels of antibiotic resistance, rapid growth, and exotoxin production. In order to understand the biofilm forming abilities of these microbes in a simulated wound environment we used a microtiter plate assay to assess the ability of these two organisms to bind to proteins that are typically found at wound sites: collagen and hyaluronan.ResultsCollagen and hyaluronan were used to coat the wells of 96-well plates in collagen:hyaluronan ratios of 0:1, 3:1, 1:1, 1:3, and 1:0 . P. aeruginosa and MRSA were inoculated as mono- and co-cultures (1:1 and a 3:1 MRSA: P. aeruginosa). We determined that coating the wells with collagen and/or hyaluronan significantly increased the biofilm biomass of attached cells compared to an uncoated control, although no one coating formulation showed a significant increase compared to any other combination. We also noted that the fold-change increase for MRSA upon coating was greater than for P. aeruginosa.ConclusionsOur study suggests that the presence of collagen and/or hyaluronan at wound sites may be an important factor that influences the attachment and subsequent biofilm formation of notorious biofilm-formers, such as MRSA and P. aeruginosa. Understanding the kinetics of binding may aid in our comprehension of recalcitrant wound infection development, better enabling our ability to design therapies that would prevent or mitigate the negative outcomes associated with such infections.

Dual immunosensor based on methylene blue-electroadsorbed graphene oxide for rapid detection of the influenza A virus antigen.

Rapid detection of influenza viral infections in poultry facilities is advantageous in several aspects such as environmental/personal safety, food-security, and socio-economy. Herein, we report the development of an electrochemical-based dual-sensor platform composed of methylene blue-electroadsorbed graphene oxide nanostructures modified with monoclonal antibodies against the HA proteins of H5N1 and H1N1. Bio-functional layers comprised of chitosan and protein-A molecules were implemented at the interface of the sensor element and antibodies, which synergistically enriched the bio-activity of immobilized antibodies for the immune complex formation. The differential pulse voltammetric signals resulted from the developed immunosensor platform exhibited a good correlation (R(2)=0.9978 for H1N1 and R(2)=0.9997 for H5N1) for the wide range of target concentrations 25-500pM). Chronoamperometric study also revealed the amplified current sensitivity of the immunoelectrodes even at the picomolar level. The proposed immunosensor design not only provides rapid analytical response time (<1min) but simplicity in fabrication and instrumentation, which paves an attractive platform for on-farm monitoring of viral infections.

Lipoxygenase-modified Ru-bpy/graphene oxide: Electrochemical biosensor for on-farm monitoring of non-esterified fatty acid.

Elevated concentrations of non-esterified fatty acids (NEFA) in biological fluids are recognized as critical biomarkers for early diagnosis of dairy cow metabolic diseases. Herein, a cost-effective, electrochemically active, and bio-friendly sensor element based on ruthenium bipyridyl complex-modified graphene oxide nanosheets ([Ru(bpy)3](2+)-GO) is proposed as a biosensor platform for NEFA detection. Electrochemical analysis demonstrates that the [Ru(bpy)3](2+)-GO electrodes exhibit superior and durable redox properties compared to the pristine carbon and GO electrodes. Target specificity is accomplished through immobilization of the enzyme, lipoxygenase, which catalyzes the production of redox active species from NEFA. Lipoxygenases retain their catalytic ability upon immobilization and exhibit changes to amperometric signals upon interaction with various concentrations of standard NEFA and serum samples. Our study demonstrates that the [Ru(bpy)3](2+)-GO electrode has the potential to serve as a biosensor platform for developing a field deployable, rapid, and user-friendly detection tool for on-farm monitoring of dairy cow metabolic diseases.