Quality Control and Compliance Key Points for the Development of Gene Microarray In Vitro Diagnostic Products

Probe Validation in Design and Development

The core of gene chip-based in vitro diagnostic products lies in probe design and target coverage. During the design phase, authoritative public databases and multiple sequence alignment should be referenced to evaluate probe specificity against target sequences and avoid cross-hybridization with non-target sequences. Validation typically requires the use of synthetic samples and a certain number of clinical samples to confirm that probes can stably bind to target nucleic acids under predefined hybridization conditions. The number of probes, uniformity of Tm values, GC content, and propensity for secondary structure are routine considerations, and specific parameters should be set according to the intended use of the product and platform characteristics. If probe design changes occur, bridging or re-validation should be performed; original parameters must not be directly carried over.

Raw Materials and Critical Material Control

Critical materials involved in gene chip products, such as chip substrates, probe raw materials, labeling reagents, and hybridization buffers, should have incoming inspection and quality release standards established. Differences in surface modification across substrate batches may affect spotting consistency and background signal; it is recommended to conduct small-scale trial production or performance evaluation of critical raw materials. When suppliers change, process suitability must be re-confirmed, and the potential impact on product performance should be analyzed. The activity and purity of biochemical raw materials such as labeling enzymes and fluorescent dyes should also be included in the control scope.

Substrate: Focus on surface modification uniformity, background fluorescence, storage stability, and batch-to-batch differences.

Probes: Focus on purity, concentration, sequence correctness, and batch-to-batch consistency.

Labeling and hybridization system: Focus on enzyme activity, fluorescence intensity, hybridization temperature, and time window.

Analytical Performance Evaluation and Batch-to-Batch Consistency

Analytical performance typically includes sensitivity, specificity, repeatability, and limit of detection. For qualitative detection products, the basis for determining the positive cutoff value or threshold must be stated; for quantitative or multi-analyte panel products, cross-reactivity and signal crosstalk between different probes should also be considered. Batch-to-batch consistency is a challenge in gene chip quality control, generally requiring that multiple consecutive batches produce consistent results for the same reference material. It is recommended to include quality control chips or internal control probes during process validation to monitor spotting volume, hybridization efficiency, and signal drift. All performance indicators should be based on validation data; absolute statements, efficacy claims, or unconfirmed clinical conclusions must not be used in the instructions for use or registration materials.

Registration Materials and Instructions for Use Specifications

Registration materials should fully present the relationship between design inputs, process validation, analytical performance, and clinical evaluation. The instructions for use must clearly state the intended use, applicable sample types, compatible instruments, storage conditions, limitations, and result interpretation methods. The result interpretation section should objectively describe which targets or signals the product detects and where combination with other tests or professional judgment is required. Performance indicators in labels and instructions for use should be based on registration testing and validation data, avoiding exaggeration of the applicable scope. For products requiring cold chain storage, general requirements for transport and post-opening stability should also be described to help users operate correctly.