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Related Concept Videos

Polyprotic Acids03:38

Polyprotic Acids

Acids are classified by the number of protons per molecule that they can give up in a reaction. Acids such as HCl, HNO3, and HCN that contain one ionizable hydrogen atom in each molecule are called monoprotic acids. Their reactions with water are:
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Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
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Related Experiment Video

Updated: Jun 13, 2026

Evaluation of Polymeric Gene Delivery Nanoparticles by Nanoparticle Tracking Analysis and High-throughput Flow Cytometry
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Evaluation of Polymeric Gene Delivery Nanoparticles by Nanoparticle Tracking Analysis and High-throughput Flow Cytometry

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pH-Dependent Structural Changes in Polyethyleneimine Affect its Gene Transfection Efficiency.

Shivalika Sharma1, Manjari Mishra1, Aswin T Srivatsav1

  • 1Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.

Small (Weinheim an Der Bergstrasse, Germany)
|June 2, 2025
PubMed
Summary

Conditioning Polyethyleneimine (PEI) at pH 1.4 before gene delivery significantly enhances transfection efficiency. However, exposure to pH 3.0 causes PEI self-assembly, impairing gene delivery and cellular uptake.

Keywords:
gene transfectionlight‐scatteringpH‐responsivenesspolyethyleneimineself‐assembly

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Area of Science:

  • Biomaterials Science
  • Gene Delivery Systems
  • Polymer Chemistry

Background:

  • Polyethyleneimine (PEI) is a widely used non-viral vector for gene delivery.
  • PEI's efficacy is linked to its pH-dependent proton-sponge mechanism.
  • PEI can self-assemble into specific structures in low-pH environments, potentially impacting gene delivery.

Purpose of the Study:

  • To investigate the correlation between the pH conditioning of free PEI chains and subsequent gene transfection efficiency.
  • To elucidate how pH-induced PEI self-assembly affects gene delivery dynamics.
  • To identify optimal pH conditions and temporal parameters for PEI-based gene transfection.

Main Methods:

  • Branched PEI chains were conditioned in aqueous solutions at varying pH levels (e.g., pH 1.4, pH 3.0) before complexation with DNA at pH 7.4.
  • Gene transfection efficiency was quantified after conditioning.
  • PEI self-assembly and micro-structuration were analyzed using techniques sensitive to structural changes (implied).

Main Results:

  • Conditioning PEI at pH 1.4 prior to DNA complexation resulted in approximately a two-fold increase in transfection efficiency.
  • PEI chains conditioned at pH 3.0 exhibited spatiotemporal deterioration in transfection efficiency.
  • Self-assembly of PEI into micron-sized fibrils between pH 2.5-4.0 was observed, leading to reduced cellular uptake and nuclear localization.

Conclusions:

  • The pH landscape and conditioning time of free PEI chains critically influence gene transfection outcomes.
  • PEI self-assembly into fibrils at intermediate acidic pH (2.5-4.0) is detrimental to gene delivery.
  • Understanding and controlling PEI's pH-dependent behavior is crucial for optimizing non-viral gene delivery systems.