Carboxymethyl chitosan/alginate/polyethylene glycol composite hydrogel for nucleic acid lysis solution storage at the point of care

Rapid nucleic acid testing (NAT) technology as an effective tool for point-of-care testing (POCT), has been widely used for health, food additive, and environmental pollution monitoring. Nucleic acid extraction (NAE) is a vital first step of NAT technology, including sample lysis, washing and elution. At present, storage of sample lysis solution for rapid NAE methods is expensive, complex and environmentally unfriendly. To address these drawbacks, a low-cost, rapid, simple, and portable material is urgently needed. Herein, we developed a pH-responsive carboxymethyl chitosan/sodium alginate/polyethylene glycol (CMCS/SA/PEG) composite hydrogel that works as a physical crosslink, then used it to store sample lysis solutions for the dry immersion method for NAE. Results showed that the CMCS/SA/PEG6000 composite hydrogel had large pore size (256.58 +/- 5.58 mu m), good wet strength (282.3 Kpa), excellent swelling rate (706.91 +/- 6.69%), high loading capacity (90.46 +/- 1.13%), good degradation capacity (77.87 +/- 1.45%), and rapid response time (15 s). The CMCS/SA/PEG6000 composite hydrogel could be loaded into a syringe and combined with filter paper to function as a simple NAE device. Efficiency of lysis of nucleic acid of saliva, whole blood, E.coli and S.aureus was 20.71 +/- 0.12%, 9.59 +/- 0.12%, 16.57 +/- 0.19%, and 29.16 +/- 0.07%, respectively. Also, nucleic acid was successfully extracted from a 30 mu L sample of saliva so the method has potential to be integrated into other platforms for NAT.