Analytical Validation of a Spiral Microfluidic Chip with Hydrofoil-Shaped Pillars for the Enrichment of Circulating Tumor Cells

The isolation of circulating tumor cells (CTCs) from peripheral blood with high efficiency remains a challenge hindering the utilization of CTC enrichment methods in clinical practice. Here, we propose a microfluidic channel design for the size-based hydrodynamic enrichment of CTCs from blood in an epitope-independent and high-throughput manner. The microfluidic channel comprises a spiral-shaped part followed by a widening part, incorporating successive streamlined pillars, that improves the enrichment efficiency. The design was tested against two benchmark designs, a spiral microfluidic channel and a spiral microfluidic channel followed by a widening channel without the hydrofoils, by processing 5 mL of healthy blood samples spiked with 100 MCF-7 cells. The results proved that the design with hydrofoil-shaped pillars perform significantly better in terms of recovery (recovery rate of 67.9% compared to 23.6% in spiral and 56.7% in spiral with widening section), at a cost of slightly lower white blood cell (WBC) depletion (depletion rate of 94.2% compared to 98.6% in spiral and 94.2% in spiral with widening section), at 1500 µL/min flow rate. For analytical validation, the design was further tested with A549, SKOV-3, and BT-474 cell lines, yielding recovery rates of 62.3 ± 8.4%, 71.0 ± 6.5%, and 82.9 ± 9.9%, respectively. The results are consistent with the size and deformability variation in the respective cell lines, where the increasing size and decreasing deformability affect the recovery rate in a positive manner. The analysis before and after the microfluidic chip process showed that the process does not affect cell viability

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

PERFORMANCE ENHANCEMENT OF MEMS-BASED MICROBIAL FUEL CELLS (mu MFC) FOR MICROSCALE POWER GENERATION

This paper reports the design, fabrication, and testing of a microliter scale Microbial Fuel Cell (mu mu MFC) based on silicon MEMS fabrication technology. mu MFC systems are operated under different loads or open circuit to compare the effect of different acclimatization conditions on start-up time. Shewanella oneidensis MR-1 is preferred to be the biocatalyst. The internal resistance is calculated as 20 k Omega under these conditions. Acclimatization of mu MFC under a finite load resulted in shorter start-up time (30 hours) when compared to the open load case. Power and current densities normalized to anode area are 2 mu W/cm(2) and 12 mu A/cm(2) respectively. When the load resistance value is closer to the internal resistance of the mu MFC, higher power and current densities are achieved as expected, and it resulted in a shorter start-up time. Further studies focusing on the different acclimatization techniques for mu MFC could pave the way to use mu MFCs as fast and efficient portable power sources

Design of a microfluidic device for immunoaffinity-based isolation of circulating tumor cells with minimal clogging

Combining bioaffinity-based techniques with microfluidics is an effective strategy for the selective isolation of rare circulating tumor cells (CTCs) among peripheral blood cells. In this scope, designing a microfluidic channel with high cell-surface interaction is crucial, which can be realized by increasing surface area via micropillars. In such microfluidic channels, the interpillar distance represents a critical design parameter, and the value is decided considering the trade-off between the possibility of clogging and CTC capture efficiency. In this study, a curvilinear microfluidic channel with a wide (150 µm) interpillar distance was developed to prevent clogging while maintaining high CTC capture efficiency. Computational fluid dynamics was used to compare the residence time of particles in the designed channels. For the proof-of-concept study, microfabricated channels were biofunctionalized for immunoaffinity-based isolation of CTCs, using anti-EpCAM antibodies. Enhanced CTC capture was enabled through the micropillars inside the channels helping the increased encounters between the cells and the antibody-functionalized surface. The curvilinear channel effectively isolated cells from MCF-7 breast cancer cell line among white blood cells, with more than 85% capture efficiency. The rate of non-specific binding of white blood cells remained below 20%. This study demonstrated the ability to increase the interactions between particles and surfaces without requiring a dense layout of the micropillars inside the microchannel, therefore minimizing the clogging possibility of the channel without sacrificing performance

Enhancement of the Start-Up Time for Microliter-Scale Microbial Fuel Cells (mu MFCs) via the Surface Modification of Gold Electrodes

Microbial Fuel Cells (MFCs) are biological fuel cells based on the oxidation of fuels by electrogenic bacteria to generate an electric current in electrochemical cells. There are several methods that can be employed to improve their performance. In this study, the effects of gold surface modification with different thiol molecules were investigated for their implementation as anode electrodes in micro-scale MFCs (mu MFCs). Several double-chamber mu MFCs with 10.4 mu L anode and cathode chambers were fabricated using silicon-microelectromechanical systems (MEMS) fabrication technology. mu MFC systems assembled with modified gold anodes were operated under anaerobic conditions with the continuous feeding of anolyte and catholyte to compare the effect of different thiol molecules on the biofilm formation ofShewanella oneidensisMR-1. Performances were evaluated using polarization curves, Electrochemical Impedance Spectroscopy (EIS), and Scanning Electron Microcopy (SEM). The results showed that mu MFCs modified with thiol self-assembled monolayers (SAMs) (cysteamine and 11-MUA) resulted in more than a 50% reduction in start-up times due to better bacterial attachment on the anode surface. Both 11-MUA and cysteamine modifications resulted in dense biofilms, as observed in SEM images. The power output was found to be similar in cysteamine-modified and bare gold mu MFCs. The power and current densities obtained in this study were comparable to those reported in similar studies in the literature

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background: Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods: This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was coprioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low-middle-income countries. Results: In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of 'single-use' consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low-middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion: This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high- and low-middle-income countries