Background: In the field of antibacterial, nanomaterials are favored by researchers because
of their unique advantages. Medicinal plants, especially traditional Chinese medicine, are
considered to be an important source of new chemicals with potential therapeutic effects, as well as
an important source for the discovery of new antibiotics. MRSA is endangering people's lives as a
kind of multidrug-resistant Staphylococcus aureus, which is resistant to tetracycline, amoxicillin,
norfloxacin and other first-line antibiotics. It is a hotspot to find good anti-drug-resistant bacteriae,
nature-originated nanomaterials with good biocompatibility.
Objective: We reported the formation of phytochemical nanoparticles (NPs) by the self-assembly
of berberine (BBR) and 3,4,5-methoxycinnamic acid (3,4,5-TCA) from Chinese herb medicine,
which had good antibacterial activity against MRSA.
Method and Results: We found that NPs had good antibacterial activity against MRSA; especially,
its antibacterial activity was better than first-line amoxicillin, norfloxacin and its self-assembling
precursors on MRSA. When the concentration reached 0.1 μmol/mL, the inhibition rate of NPs
reached 94.62%, which was higher than that of BBR and the other two antibiotics (p < 0.001). It
was observed by Field-Emission Scanning Electron Microscopy (FESEM) that NPs could directly
adhere to the bacterial surface, which might be an important aspect of the antibacterial activity of
NPs. Meanwhile, we further analyzed that the self-assembly was formed by hydrogen bonds and π-
π stacking through Ultraviolet-Visible (UV-vis), Fourier Transform Infrared Spectroscopy (FT-IR),
hydrogen Nuclear Magnetic Spectrum (1H NMR), and powder X-ray Diffraction (pXRD). NPs’
morphology was observed by FESEM and TEM. The particle size and surface charge were characterized
by Dynamic Light Scattering (DLS); and the surface charge was -31.6 mv, which proved
that the synthesized NPs were stable.
Conclusion: We successfully constructed a naturally self-assembled nanoparticle, originating from
traditional Chinese medicine, which had a good antibacterial activity for MRSA. It is a promising
way to obtain natural nanoparticles from medicinal plants and apply them to antibacterial therapy.