Poly-L-histidine coated microfluidic devices for bacterial DNA purification without chaotropic solutions

Area of Science:

• Biotechnology
• Analytical Chemistry
• Materials Science

Background:

• Traditional DNA purification methods often use ethanol or chaotropic agents, which can inhibit downstream molecular analyses.
• Polymeric microfluidic devices offer potential for integrated sample preparation but require robust surface functionalization for efficient nucleic acid binding.

Purpose of the Study:

• To develop a disposable polymeric microfluidic device for Salmonella DNA purification via solid phase extraction (SPE).
• To establish a novel, ethanol- and chaotropic-free, pH-dependent protocol for on-chip DNA purification.
• To evaluate the efficiency and recovery of the developed microfluidic DNA purification system.

Main Methods:

• Fabrication of a disposable polymeric microfluidic device with micro-nanotextured channels.
• Surface functionalization using L-histidine or poly-L-histidine after oxygen plasma treatment.
• Implementation of a pH-dependent solid phase extraction protocol for Salmonella DNA binding and elution.
• Analysis of DNA recovery efficiency from purified DNA and Salmonella cell lysates.

Main Results:

• Poly-L-histidine modification yielded higher amine group density on the microfluidic channels.
• Achieved high recovery efficiency of at least 550 ng of isolated Salmonella DNA.
• Successfully purified DNA from Salmonella cell lysates corresponding to <5000 cells (0.026 ng DNA).
• The protocol effectively avoided the use of ethanol and chaotropic solutions.

Conclusions:

• The developed microfluidic device and pH-dependent protocol enable efficient Salmonella DNA purification.
• The absence of inhibitory substances makes this method suitable for integration into Lab-on-a-chip (LOC) platforms for pathogen detection.
• This approach offers a promising alternative for general DNA purification in microfluidic applications.