Analysis of the Antibacterial Mechanism of Polyhexamethylene Guanidine (PHMG)

Polyhexamethylene guanidine (PHMG) is a polymer bactericide, and its antibacterial effect stems from its unique physicochemical mechanism and molecular structure characteristics. The following are its core antibacterial principles and scientific basis:

1. Positive - Negative Charge Adsorption

The PHMG molecular chain contains a large number of positively charged guanidine groups, while the surfaces of microorganisms such as bacteria and viruses usually carry negative charges (e.g., the phospholipid bilayer of the bacterial cell membrane). Through electrostatic adsorption, PHMG can quickly bind to the surface of microorganisms, forming a polymer coating layer that blocks the material exchange channels between microorganisms and the outside world.

2. Disruption of Cell Membrane Structure and Function

2.1 Alteration of Membrane Permeability

After the positively charged groups of PHMG adsorb microorganisms, they insert into the cell membrane through hydrogen bonding and hydrophobic interactions, disrupting the arrangement of the phospholipid bilayer and causing pores to appear in the cell membrane. Experiments have shown that low - concentration PHMG can cause the leakage of small - molecule substances such as potassium ions, while high - concentration PHMG can lead to the collapse of the membrane structure and a large - scale loss of cell contents.

2.2 Inhibition of the Synthesis of Key Metabolic Substances

PHMG binds to phosphate substances (such as adenosine triphosphate, ATP) on the cell membrane, interfering with liposome synthesis and blocking the energy metabolism and cell division and proliferation of microorganisms. Electron microscopy has confirmed that after treatment with PHMG, the cell membranes of bacteria show wrinkles and ruptures, and the internal structure is severely damaged.

3. Broad - Spectrum and Long - Acting Bacteriostatic Mechanisms

3.1 Broad - Spectrum Bactericidal Ability

PHMG is effective against Gram - positive bacteria (e.g., Staphylococcus aureus), Gram - negative bacteria (e.g., Escherichia coli), fungi (Candida albicans), and viruses (HIV). Experiments have shown that a 1000 mg/L aqueous solution of PHMG can achieve a killing rate of 99.99% against Candida albicans after 20 minutes of action.

3.2 Long - Acting Bacteriostatic Properties

The polymer structure of PHMG can form an antibacterial film on the surface of objects, continuously inhibiting the regeneration of microorganisms. For example, after treating textiles with a 0.1% concentration of PHMG, the antibacterial effect can withstand 120 washes.

4. Safety and Environmental Friendliness

4.1 Low Toxicity and Non - Irritation

Toxicological studies have shown that PHMG has high safety for mammals. The acute oral LD50 of a 1% solution in mice is > 5000 mg/kg, which is considered to be of actual non - toxicity. A 0.5% solution is non - irritating to the skin and eyes.

4.2 Environmental Compatibility

PHMG is biodegradable in the natural environment (degradation rate > 90%), and there are no heavy metals or volatile organic compounds remaining. It is suitable for use in sensitive scenarios such as food processing and aquaculture.

Technical Advantages in Application

Wide pH Adaptability: It maintains stable activity in the pH range of 5.0 - 9.0, making it suitable for both acidic environments (e.g., the surface of fruits) and weakly alkaline environments (e.g., detergents).

Non Corrosive: It does not corrode metals, plastics, and other materials, and can be used for the long - term disinfection of medical equipment and food processing equipment.

Note: When using PHMG, avoid mixing it with anionic surfactants (such as soap) to prevent a reduction in the bactericidal effect.

PHMG achieves efficient sterilization through multiple mechanisms, and it combines safety with environmental protection characteristics. It has now been included in the recommended list of the "Technical Specifications for Disinfection" in China and has become a preferred alternative to chlorine - containing disinfectants.