Surface plasmon resonance biosensing: Approaches for screening and characterising antibodies for food diagnostics.

Research in biosensing approaches as alternative techniques for food diagnostics for the detection of chemical contaminants and foodborne pathogens has increased over the last twenty years. The key component of such tests is the biorecognition element whereby polyclonal or monoclonal antibodies still dominate the market. Traditionally the screening of sera or cell culture media for the selection of polyclonal or monoclonal candidate antibodies respectively has been performed by enzyme immunoassays. For niche toxin compounds, enzyme immunoassays can be expensive and/or prohibitive methodologies for antibody production due to limitations in toxin supply for conjugate production. Automated, self-regenerating, chip-based biosensors proven in food diagnostics may be utilised as rapid screening tools for antibody candidate selection. This work describes the use of both single channel and multi-channel surface plasmon resonance (SPR) biosensors for the selection and characterisation of antibodies, and their evaluation in shellfish tissue as standard techniques for the detection of domoic acid, as a model toxin compound. The key advantages in the use of these biosensor techniques for screening hybridomas in monoclonal antibody production were the real time observation of molecular interaction and rapid turnaround time in analysis compared to enzyme immunoassays. The multichannel prototype instrument was superior with 96 analyses completed in 2h compared to 12h for the single channel and over 24h for the ELISA immunoassay. Antibodies of high sensitivity, IC50's ranging from 4.8 to 6.9ng/mL for monoclonal and 2.3-6.0ng/mL for polyclonal, for the detection of domoic acid in a 1min analysis time were selected. Although there is a progression for biosensor technology towards low cost, multiplexed portable diagnostics for the food industry, there remains a place for laboratory-based SPR instrumentation for antibody development for food diagnostics as shown herein.

Qualitative determination of carbon black in food products.

Carbon black (C.I. 77266) is an insoluble pigment produced by the partial combustion of hydrocarbons. The pigment is known by several synonyms, including vegetable carbon, lamp black and carbon ash, that correspond to the raw materials and methods used for its production. Vegetable carbon (E153) is permitted for use in colouring food in the European Union. The US Food and Drug Administration (USFDA) has not approved the use of any type of carbon black for colouring food, although the agency batch certifies the pigment as D&C Black No. 2 for use in colouring certain cosmetics. Since carbon black (as vegetable carbon) may be present in food products offered for import into the United States, the USFDA's district laboratories need a qualitative analytical method for determining its presence. We have developed an extraction method for this purpose. A sample is broken down and dissolved with nitric acid. The resulting solution is filtered and treated with hydrochloric acid to dissolve any black iron oxide also present as a colour additive. A black residue remaining on the filter paper indicates the presence of carbon black in the food. We confirmed the presence of carbon black in residues from several standards and food products using Raman spectroscopy. The limit of detection for this method is 0.0001%.

The prevalence of pulmonary and upper respiratory tract symptoms and spirometric test findings among newspaper pressroom workers exposed to solvents.

To investigate the relationship between exposure to organic solvents and the presence of pulmonary and upper respiratory tract mucous membrane symptoms, we conducted a cross-sectional study of 215 newspaper pressroom workers who were occupationally exposed to organic solvent and lubricant mixtures. Thirty-four compositors, who were not occupationally exposed to the solvents or lubricants, served as controls. Pressroom workers and compositors underwent spirometric testing and were also asked about the presence of cough, phlegm, hemoptysis, dyspnea, wheezing, chest tightness, nose or throat irritation, eye irritation, and sinus trouble. The spirometric results did not significantly differ between the two groups. However, the pressroom workers were significantly more likely to report pulmonary or upper respiratory tract mucous membrane symptoms than were compositors (P < 0.005). An exposure-response relationship could be demonstrated when comparing the number of solvents exposed with the total number of symptoms (P < 0.001). Similarly, an exposure-response relationship could be demonstrated when comparing the frequency of use of each of the seven solvents with the total number of symptoms (P < 0.002). Each of these findings was supported in a multivariable linear regression model that adjusted for potential confounders such as age, smoking history, and number of years in the industry. A high prevalence of these symptoms was reported even though the degree of exposure to solvents and lubricants was within the current permissible exposure limits.

Occupational skin disease in newspaper pressroom workers.

Studies of printing industry tradespeople have reported an increased problem of dermatologic abnormalities, including contact dermatitis and dermatitis attributed to solvent exposure. The current cross-sectional health survey of dermatological conditions were conducted in a follow-up of perceived skin abnormalities among newspaper pressroom workers. We surveyed 215 pressroom workers and 34 compositors at a large northeastern US newspaper printing facility. Our findings indicate that printing pressroom workers reported skin condition symptoms at a significantly higher rate than did the compositor referent group. Pressroom workers also were found to be at a significantly elevated risk of developing dermatitis after self-reported exposure to certain commonly used solvents. This emphasizes the need for proper work practices, product substitution where possible, and appropriate protective glove use by newspaper pressroom workers.

The presence of urinary cellular sediment and albuminuria in newspaper pressworkers exposed to solvents.

To investigate the relationship between exposure to organic solvents and the presence of increased urinary cellular sediment, we conducted a cross-sectional study of 215 newspaper pressroom workers who were exposed to solvent and lubricant mixtures. Thirty-two compositors were surveyed as referents. Industrial hygiene measurements showed low-level airborne exposures to organic solvents (primarily naphthas) and minimal airborne exposure to glycol ethers. There was a high prevalence of solvent-related dermatitis indicating there was significant dermal exposure to these substances. Pressworkers were exposed to solvent mixtures that were associated with dose-related increases in leukocyturia alone or in urinary cellular sediment (erythrocyturia and/or leukocyturia). The presence of urinary cellular sediment was associated with increasing frequency of use of five particular organic solvent mixtures. These results suggest that the increase in urinary cellular sediment may be due, at least in part, to the effects of solvents on the kidney. Consistent with this hypothesis, 16% of pressmen and no compositors were found to have primarily low-grade albuminuria detectable by dipstick. Workers with urinary cellular sediment were significantly more likely to have detectable albuminuria. Albuminuria was more likely to occur with increased frequency of use of four particular solvent mixtures. The presence of urinary cellular sediment was less likely to occur with occasional use of analgesics suggesting a possible etiologic role for acute or chronic urinary tract inflammation.