Frequently Asked Questions
An excipient is the bulking agent that forms the hard shell of the DxSphere. It also serves as cryogenic protection during freeze-drying, as well as a stabilizing agent for long term ambient storage conditions.
What excipients are typically used when lyophilizing a reagent?
We do not have a fixed excipient that works for all reagent mixtures. We advise our customers to run an initial screening experiment with several excipients (typically 2-5) to determine the best excipient for each specific reagent/component and application. Evik Diagnostics R&D experts can recommend a short list of preferred excipients for immunoassays, molecular and enzymatic assays.
We have many different components in our reagent, is this a problem?
Many of our customers use multi-component reagents without a problem but our team would be able to advise on your formula and make any recommendations.
Can we ship reagents to you pre-mixed?
We can receive your mixes ready to dispense with pre-mixed excipients or our team can prepare and formulate the reagent/components following your working instructions/protocols.
How are excipients added to the reagent mixture?
Excipients can be added to the reagent mixture either as a stock solution or dry powder. The Evik Diagnostics R&D team will provide more direction during the development planning phase.
What amount of excipient will you use in the assay formulation?
Excipients and their concentrations are selected based on the specific needs of our customer’s assay. We consider the bulking, lyo-protectant, and stabilization needs of our customer’s assay when selecting excipients and their concentrations. On average, our excipient concentration is typically between 5 and 20%.
We use glycerol to stabilize our reagent, is that okay?
Glycerol-free (or lyo friendly) reagents produce the best results. Some of our customers use dialysis or spin desalting columns to remove glycerol from their formulas. In some cases, up to 1% glycerol in the final formula can be tolerated.
If we have a final reaction volume of, for example, 20 µL, does the DxSphere volume have to be the same (20 µL)?
The DxSphere volume reflects the volume of active assay component plus volume of excipient. DxSphere volume is not the same as the final volume of the reaction.
How big are DxSpheres?
We reliably and accurately dispense volumes from 5-30uL which includes the volume of active assay plus excipient. Typically, the size of the DxSphere size is related to the size of the liquid drop used to form the DxSphere.
How quickly does a DxSphere dissolve in solution?
| Drop Volume (µL) | Estimated* DxSphere Diameter (mm) |
|---|---|
| 5 | 2.02 |
| 7.5 | 2.31 |
| 10 | 2.54 |
| 12.5 | 2.74 |
| 15 | 2.91 |
| 17.5 | 3.06 |
| 20 | 3.20 |
| 22.5 | 3.33 |
| 25 | 3.45 |
| 27.5 | 3.56 |
| 30 | 3.66 |
DxSpheres are rapidly reconstituted in any required volume of sample or diluent.
What is the stability of lyophilized DxSpheres?
Reagent stability depends on specific reagent formulas and excipients. Evik Diagnostics supports our customer’s assay development processes and stability studies by offering our insight and advice on excipient selection and other factors affecting stability. Historically, most of our customers achieve one to two year’s DxSphere stability.
Can you package my DxSpheres in my special vial, tube, or custom device?
Yes, our team can place your DxSpheres into standard tubes, vials or plates and can also package into custom cartridges or other devices.
When you package, do you seal the DxSpheres into further foil sealed pouches?
Our standard packaging is to place all DxSpheres in bulk, into glass or plastic containers that are sealed in foil pouches with a desiccant. However, if you require special outer packaging, our team is happy to discuss other options.
What is the advantage of using lyophilized DxSpheres in bead format versus other forms of lyophilized assay reagent such as a cake or liquid reagents directly in a custom or point-of-care device such as a microfluidic cartridge?
Many factors can be considered from stability, to benefits in shipping and cost effectiveness. Please refer to our white paper on our website for more information.
What if we want to trial your lyophilization services with our reagent(s), what is the initial step?
We recommend starting with the manufacture of small, manually dispensed experimental batches. Our R&D team can assist in your design of proof-of-concept batches.
What is the typical duration of development projects?
All assays have different degrees of complexity and optimization requirements. We produce as many developmental batches as required to complete each customer’s design and development process. Our customers lead their projects and determine how quickly they wish to proceed.
Does Evik Diagnostics have ISO 13485 Certification?
Yes, you can download our ISO 13485 Certificate here.
Is Evik Diagnostics GMP compliant?
Evik Diagnostics manufactures to standard operating procedures in an ISO 13485:2016 compliant facility. Our processes are designed to comply with Good Manufacturing Practice standards.