Purification of nucleic acids is an essential procedure for most experiments in molecular biology. In this paper, the freeze-squeeze method with some modifications is proposed as an alternative methodology for the purification, concentration and recovery of small DNA fragments from agarose gels. The advantage of this alternative methodology is that it enables the recovery of fragments that are less than 100 bp in length and enables suspension of products in smaller volumes compared to several commercially available kits. In addition, the purified fragments were re-amplified by PCR and used for cloning and sequencing. Moreover, this protocol was used to perform the isolation and identification of microRNAs from Giardia lamblia, as previously reported. This protocol has the advantage of being inexpensive and easy and can be employed for various molecular applications. The advantages of this protocol include •A modified classical method was used for purification of small DNA fragments from G. lamblia.•The modified freeze-squeeze method was more efficient in cleaning up small DNA fragments from agarose gels compared to commercial kits.•The modified method allows concentration and recovery of fragments up to 60 bp in length.•The modified freeze-squeeze method allows re-suspension of the products in volumes of up to 2.5 μL.
Keywords: Giardia lamblia; PCR; agarose gel; purification; small DNA.