Chemical Changes Over Time Associated with Protein Drying

3D-printed micro-pore evaporator for increasing concentration of analytes in aqueous solutions

To address the detection limit challenges of analytical instruments at low concentrations, this study explores the development of a concentrator, fabricated via micro-3D printing technology, relying on solvent evaporation through micro-pores. The operating temperature can be as low as room temperature, allowing for compatibility with biomolecules that are sensitive to high temperatures. Moreover, the device is suitable for processing small sample volumes ranging from hundreds to tens of microliters. There are three designs of the hydrophilic biocompatible polymer tube, each featuring micro-pores with diameters of 30, 50 and 70 μm, spaced at distances of 150, 250 and 350 μm, respectively. All designs have the same total length of 16 mm and identical contact surface area. The tube is surrounded by an outer tube for a sweeping gas at a flow between 20 and 100 mL min-1 for evaporation rate control. Theoretical calculations and experimental data were used to quantify device's performance and capabilities. Experiments conducted with deionized water and with aqueous glucose solutions demonstrate the device's capability to achieve up to a 10-fold concentration increase. The study also addresses potential issues such as analyte loss and the influence of various parameters like sweeping gas flow rates and liquid feeding rates on the concentration process. This work demonstrates the potential of the micro-3D printed device as a reliable and efficient method for sample concentration, critical for enhancing detection sensitivities for various applications such as bioassays and biosensors.

Influence of drying time on the removal of blood from medical devices

BACKGROUND

When processing surgical instruments after use, the safe, residue-free removal of blood and blood-containing soiling is one of the most important tasks. There are recommendations from various working groups regarding the ideal timeframe for cleaning used instruments in order to ensure safe disinfection and sterilization and avoid adverse effects. These are generally based primarily on practical experience and there is little systematic work on this topic.

AIM

In the present study, cleaning experiments with test specimens previously contaminated with sheep's blood were performed, and in this way the effects of the drying time of whole blood on the results of the subsequent cleaning were examined.

METHODS

Reflecting practice, both visual and spectroscopic methods were used to quantify residual protein. The experimental results were evaluated both as a function of the drying time and the residual moisture of the blood.

FINDINGS

Drying blood was particularly difficult to remove within the first 1-2 h. In this phase, in which the blood is coagulated but not yet completely dried, considerably more protein residues remained on the test specimens after cleaning than after longer standing times.

CONCLUSION

There is a timeframe for the removal of blood residues in which optimum cleaning results can be expected. As a consequence, there are also standing times that are disadvantageous for reprocessing. Based on the experimental data, it was deduced that this optimum time is either directly after contamination or in the range of >3 h and <24 h after soiling.

Validation of the Device Feature Approach for Reusable Medical Device Cleaning Evaluations

The identification of worst-case device (or device set) features has been a well-established validation approach in many areas (e.g., terminal sterilization) for determining process effectiveness and requirements, including for reusable medical devices. A device feature approach for cleaning validations has many advantages, representing a more conservative approach compared with the alternative compendial method of testing the entirety of the device. By focusing on the device feature(s), the most challenging validation variables can be isolated to and studied at the most difficult-to-clean feature(s). The device feature approach can be used to develop a design feature database that can be used to design and validate device cleanliness. It can also be used to commensurately develop a quantitative cleaning classification system that will augment and innovate the effectiveness of the Spaulding classification for microbial risk reduction. The current study investigated this validation approach to verify the efficacy of device cleaning procedures and mitigate patient risk. This feature categorization approach will help to close the existing patient safety gap at the important interface between device manufacturers and healthcare facilities for the effective and reliable processing of reusable medical devices. A total of 56,000 flushes of the device features were conducted, highlighting the rigor associated with the validation. Generating information from design features as a critical control point for cleaning and microbiological quality will inform future digital transformation of the medical device industry and healthcare delivery, including automation.