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Also read this article is very helpful

Article MicroRNAs Specific Primer Design using miRNA Design Tool

Steps for Designing VN Primers for miRNA:

1-Identify Target miRNA Sequences

2-Select Regions for Primer Binding

3-Design the Forward VN Primer

4-Design the Universal Reverse Primer

5-Check Specificity: Use tools like BLAST to check the specificity of your designed primers against the genomic or transcriptomic

6-Consider Melting Temperature (Tm): ideally within 2-5°C of each other

7-Optimize PCR Conditions: After designing the primers, optimize the PCR conditions (annealing temperature, extension time) for best results.

Tools for Primer Design:

Primer3: A widely used tool for designing primers.

OligoCalc : For calculating Tm and other properties.

UCSC Genome Browser: To check for conservation and specificity.