Development of label-free detection systems targeting food-borne pathogens

Food-borne pathogens and food safety-related outbreaks have come to the forefront over recent years. Estimates on the annual cost of sicknesses, hospitalizations, and deaths run into the billions of dollars. There is a large body of research on the subject of detection of food-borne pathogens, however, the widely accepted current systems are limited by high reagent costs, lengthy time to completion, and expensive equipment. This work has been developed with the goal of focusing on minimizing the time and reagent cost of two of the most common types of rapid, food-borne pathogen detection systems, i.e. immunoassays and real-time polymerase chain reaction assays. The first aim was to develop the proof-of-concept methodology for a label-free immunoassay technique utilizing photonic crystal biosensors targeting bacteria, specifically E. coli O157:H7. In this project, it is shown that detergent-lysing of the cells and extraction of their membrane antigens allows for the detection of down to 1E7 CFU/mL. Optimization of the blocking scheme takes the assay one step further and allows for specific detection of E. coli O157:H7 over E. coli K12. The second aim was to develop a label-free method for determining changes in DNA concentration as it relates to food-borne pathogen-targeted polymerase chain reaction assays. For this goal, impedance spectroscopy studies were carried out to characterize the system???s capability in determining changes in concentration of purified DNA in DI water. To adequately measure the change in DNA concentration in a PCR solution, it was necessary to go through a purification and precipitation step to minimize the effects of primers, PCR reagents, and especially excess salts. It was shown that the purification and precipitation of the fully amplified PCR reaction showed a similar trend to the pure DNA in DI water characterization tests. In developing the two versions of label-free detection systems, this work has brought cheaper, faster, smaller biosensors one step closer to reality

Considerations on using SU-8 as a construction material for high aspect ratio structures

This paper discusses two material aspects of SU-8 that have up till now been insufficiently documented. We present initial results on the outgassing behavior and a study on the dielectric properties of SU-8 at high bias voltage. The dielectric strength is determined to be at least 2 MV/cm. These elements are investigated in the light of plans to manufacture an SU-8 based Micro-Channel Plate (MCP). Although the outgassing properties and dielectric strength are favorable the patterning capabilities are expected to limit the use of such an MCP

Double-Duty Actions: Seizing Program and Policy Opportunities to Address Malnutrition in all its Forms

Actions to address different forms of malnutrition are typically managed by separate communities, policies, programmes, governance structures, and funding streams. In contrast, double duty actions, which aim to simultaneously tackle both undernutrition and problems of overweight, obesity and diet-related non-communicable diseases (DR-NCDs) have been proposed as a way to effectively address malnutrition in all its forms in a more holsitic way. This paper identifies ten double duty actions that have strong potential to reduce the risk of both undernutrition and obesity/DR-NCDs. It does so by : 1) summarizing evidence on common drivers of different forms of malnutrition; 2) documenting examples of unintended harm caused by some undernutrition-focused programmes on obesity/DR-NCDs; and 3) highlighting a few examples of first double duty actions undertaken to tackle multiple forms of malnutrition. We find that undernutrition and obesity/DR-NCDs are intrinsically linked through early life nutrition; dietary quality; food environments; and socioeconomic factors. There is some evidence that undernutrition-focused programs have raised risks of poor quality diets and obesity/DR-NCDs, especially in countries undergoing a rapid nutrition transition. The paper builds on this evidence to develop a framework to guide the design of double duty approaches and strategies, and defines the first steps needed to deliver them. With a clear package of double duty actions now identified, there is an urgent need to move forward with double duty actions to address malnutrition in all its forms