Immunoassays are the center of most bioanalytical strategies utilized in medical and analysis settings, permitting for correct detection and quantification of biomolecules.
The detection and quantification of an analyte is achieved utilizing seize reagents, often antibodies or antigens. The binding interactions between the analyte and the seize reagent are extremely delicate and particular, permitting for correct and exact measurements.
Transferring an immunoassay to a point-of-care system generally is a difficult course of. The normal ELISA approach typically requires a number of timed incubation steps, skilled personnel, and costly gear with lengthy delays from pattern to reply.
What impressed the event of the modular platform?
Current developments growing immunoassays that may be deployed on the level of care. Nonetheless, making certain accuracy and precision in assay transferability stays a vital problem. However what if there was a flexible resolution that might ease that transition and be modular to completely different assays? Introducing a modular platform that mixes a customizable fluidic actuation, reagent storage, detection methodology, and interface with gear permits the creation of a flexible resolution as an intermediate bridge between assay improvement and a conveyable POC (Determine 1).
Overview and necessities of the modular platform
Earlier than growing the modular system, let’s take a step again and re-examine the steps wanted to switch an immunoassay to a disposable cartridge. Earlier than diving into the main points, it’s important to ask questions like what the workflow for the assay appears to be like like, i.e., aggressive or Sandwich ELISA, what kind of detection methodology is getting used – optical or electrochemical, and how much pattern is being examined. Moreover, it’s best to contemplate whether or not any pattern pre-processing or reagent mixing is important and what high quality management measures are required. As soon as these questions are found out, the system will be tailored to the precise necessities of the assay.
The platform (Determine 2), consisting of an instrument and a cartridge, was created to be readily adaptable to handle all these queries, some managed by the instrument half and others integrated right into a modular cartridge. The instrument half takes care of fluidic actuation by built-in pumps, solenoid valves, and bubble trappers; detection by built-in potentiostat or attaching it to a microscope; and communication by USB. The modular cartridge incorporates valves, a response chamber, a mixing stage, waste dealing with and completely different reagent storage and introduction strategies. It additionally interfaces with the pattern preparation cartridge and the goal floor, i.e., pre-functionalized and antibody-coated screen-printed electrodes or glass slides.
Issues when designing the modular cartridge.
The cartridge is a crucial part within the point-of-care system, but figuring out the suitable type issue for the cartridge is difficult. It requires a collection of trial-and-error processes to attain correct dimensioning, ample mixing, materials choice, reagent compatibility, and environment friendly bonding. Our modular cartridge (Determine 3) has eradicated these challenges from the event course of by contemplating the next:
- Reagent storage and pattern introduction
The complexity of the assay determines which reagents needs to be launched or saved on the cartridge. The cartridge is designed to accommodate as much as 5 (5) completely different reagents utilizing varied strategies, together with blister packs, plugs containing lyophilized reagents, lyophilized beads, a liquid tank, and a syringe inlet. It may possibly course of varied samples, together with blood, saliva, urine, and different bodily fluids. The cartridge can alter to the pattern’s quantity, starting from µL to mL, by optimizing channel dimensions and fluid circulate and minimizing useless quantity.
In particular assays, like aggressive ELISA, mixing the pattern with a recognized goal analyte focus could also be obligatory earlier than the enzyme can additional bind with it. For this objective, a mixing module is included within the cartridge and may combine two separate reagents by activating the built-in valves.
- Fluid actuation
To allow modularity, fluid actuation is achieved through mp6 micropumps or vacuum pumps. These pumps permit exact and correct fluid actuation, leading to dependable and constant outcomes. A bubble trapper can also be built-in into the system to take away air bubbles when obligatory.
- Optical or Electrical Detection
The response chamber, a cartridge’s sensing area, is the place the binding interplay and the detection occur. It’s designed to be related to pre-functionalized and antibody-coated surfaces, similar to screen-printed electrodes for electrochemical detection or glass slides for colorimetric detection. This system permits for simple swapping of the electrodes/glass slides whereas utilizing the identical cartridge for a number of assays. For electrochemical detection, a PalmSens Emstat potentiostat is embedded throughout the system for direct detection. However, the instrument matches inside a custom-built microscope for optical assays.
- Waste dealing with
The cartridge consists of absorbent pads and waste containers that seize any waste generated in the course of the course of.
General, the modular platform acts as an intermediate bridge between assay improvement and the ultimate level of care. It’s a important step in the direction of streamlining the product improvement course of for diagnostics. The platform’s modularity permits shoppers to scale back the time and assets required to confirm the assays and develop new cartridge-based diagnostic gadgets.
 Per ISO 22583:2019 and ISO 15189:2022, testing that’s carried out close to or on the website of a affected person.
Picture: StarFish Medical
Khaled Youssef is Bio Services Microfluidics Engineer at StarFish Medical.