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Raw Materials and Ideas for In Vitro Diagnostics

Ⅰ. Raw materials for in vitro diagnostics

1. Antigen and antibody

Immunoreagents can generally be divided into two processes including immune response and color reaction. The immune response is the core, and the test substance is specifically separated from the complex sample. The quality of this link directly determines the core quality of the entire reagent.

In industrial production, the antibodies used in immunoassays are generally expressed by engineered bacteria to immunize animals and prepare polyclonal or monoclonal antibodies. Then the obtained antibodies are paired and screened, and the appropriate pair is selected for immunoassay. In this process, there are many application problems because the antigens to be tested are generally natural antigens and the preparation and screening of antibodies generally use recombinant antigens. For antibody manufacturers, It is worth paying attention to.

2. Special ingredients

The immune response is a fragile non-covalent bonding process. The entire reaction is affected by time, interferences, bridges, structural analogs and so on. In order to eliminate these adverse effects, some special components are generally added to the buffer system. The ingredients are defined as secondary IVD raw materials and detailed in the process.

Ⅱ. The idea of in vitro diagnostics

We analyze the raw materials and processes of in vitro diagnostics in order to find a suitable R&D idea, guide the R&D process and improve R&D efficiency. The whole R&D idea is divided into product R&D and improvement R&D.

1. Product development

Product research and development is a process from scratch, most of which are based on existing in vitro reagent on the market to develop products that our company does not have. This process accounts for the bulk of research and development, and we further subdivide it into three processes including preliminary research and development, pre-clinical experiments, and in vitro diagnostics test stability. For all research and development, we must know how a performance project is evaluated, what factors will affect the performance, and how to improve it. Let's take the double-antibody sandwich as an example.

(1) Preliminary research and development. During initial research and development, three active ingredients are generally emphasized including coating antibody, detection antibody, and calibrator. Coated antibodies and detection antibodies will have an empirical concentration. The calibrator generally uses a suitable matrix to dilute the antigen or high-value samples. The obtained gradient concentration is assigned by a third party and traced back to international, national or corporate standards.

Most of the preliminary research and development of in vitro diagnostic solutions are done in pair screening. Only three performance evaluation items of detection limit, linear range, and reportable range are needed to screen candidate pairs. For example, if you get 10 strains of antibodies, you can make 100 pairs for screening, and select a number of preliminary available candidate pairs.

For the preliminary screening of candidate pairs, the precision, accuracy (recovery experiment), interference experiment evaluation, through these experiments, the second screening of candidate pairs.

(2) Pre-clinical experiment. After the preliminary research and development of serum samples that are not involved in clinical are completed, certain candidate pairs are obtained and pre-clinical experiments are performed, mainly to evaluate the accuracy and the reference value interval.

(3) Stability test. Through the above two steps, the in vitro diagnostic kit is preliminarily formed, and the stability of the active components including pre-coated plates, calibrators, and enzyme-labeled antibodies needs to be evaluated and improved one by one until the requirements are met.

2. Improve research and development

The development of the entire IVD kit is ultimately for the detection of clinical serum samples. All analytical performance evaluation items are also designed for this purpose. However, during the entire development process, whether it is a pre-clinical trial, a formal clinical trial, or a paired clinical trial. The amount of serum samples is very limited, at most even a small trial production is completed. When the actual product is on the market and in clinical application, as the sample size expands, many problems that have not been exposed before will be exposed in a concentrated manner. Sufficient data must be collected and improved research and development must be carried out.

Generally, at this stage, the samples that are not clinically consistent, especially false positive and false negative samples, need to be tested and compared with in vitro diagnostic reagents from different manufacturers, component analysis and so on. This process will be done in pre-clinical and formal clinical trials. In preparation for clinical and formal clinical trials, it is necessary to analyze samples that are seriously inconsistent with the test values, but do not cause false positives or false negatives.