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Bis-MPA Dendron with Ammonium Functionalities Offers Effective Penetration in P.aeruginosa Biofilms

Future exploitation of these dendrimers as a new antimicrobial strategy for infection control.

The threat of antimicrobial-resistant bacterial infection becoming the number one cause of death by the year 2050

Biofilms are three-dimensional microbial aggregates responsible for 60-80% of all microbial infections. These infecting organisms produce extracellular polymeric substances (EPS) which impede the effective penetration of most antimicrobials. Pseudomonas Aeruginosa is one of the microbials that cause a range of infections in the human body. One example would be the negative effect on cystic fibrosis patients as a result of the extensive production of EPS.

Previous studies on antimicrobial nanoparticle penetration and accumulation in biofilms have mainly focused on the effect of positive and negative charges on nanoparticles, however, no clear correlation was observed.

Biofilm penetration by antimicrobials is dependent on the availability of transportation channels in biofilms with sufficient width, the diffusion coefficient of antimicrobials, and their interaction with the channel walls (EPS matrix or bacterial cell surface). It is also known that dendrimers, when composed of antimicrobial peptides, are able to kill planktonic bacteria, prevent biofilm formation and use as an antimicrobial nanocarrier.

In a new study, bis-MPA dendrons with ammonium, carboxyl and hydroxyl periphery functional were investigated to determine how different peripheral compositions influence the degree of penetration into P.aeruginosa biofilms. Findings show that penetration and accumulation of dendrons into biofilm is controlled by their pH-responsive peripheral composition. Dendrons with cationic ammonium( positively charged) peripheral groups tend to stay near the top of biofilm due to strong electrostatic double-layer interaction whereas dendrons with anionic carboxyl(negatively charged) and neutral hydroxyl functionality tend to penetrate deeper but is at the expense of being easily washed-out. This offers a better understanding of the interaction between dendrimers and biofilm during penetration and accumulation and offers new perspectives of controlling the accumulation depth of dendrimer inside a biofilm.

In view of the increasing threat of microbial infection, these dendrons and dendrimers could be exploited as a new antimicrobial strategy for infection control in the future.

For in-depth information please refer to the research paper below:

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