Construction of biocompatible bovine serum albumin nanoparticles composed of nano graphene oxide and AIEgen for dual-mode phototherapy bacteriostatic and bacterial tracking

Abstract

Background: Efficient and highly controllable antibacterial effect, as well as good biocompatibility are required for antibacterial materials to overcome multi-drug resistance in bacteria. Herein, nano graphene oxide (NGO)-based near-infrared (NIR) photothermal antibacterial materials was schemed to complex with biocompatible bovine serum albumin (BSA) and aggregation-induced emission fluorogen (AIEgen) with daylight-stimulated ROS-producing property for dual-mode phototherapy in the treatment of antibiotic resistance bacteria.

Results: Upon co-irradiation of daylight and NIR laser, NGO-BSA-AIE nanoparticles (NPs) showed superiorly antibacterial effect (more than 99%) both against amoxicillin (AMO)-resistant Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) by comparison with sing-model phototherapy. Meanwhile, the NGO-BSA-AIE NPs displayed prominent stability and excellently controllable biocompatibility. More importantly, under daylight irradiation, the AIEgen not only produced plentiful ROS for killing bacteria, but also presented fluorescence image for tracking bacteria.

Conclusions: Hence, the designed system provided tempting strategy of employing light as impetus for tracking bacterial distribution and photothermal/photodynamic synergistic treatment of antibiotic resistance antibacterial.

Keywords: Aggregation-induced emission; Bacterial tracking; Biocompatibility; Dual-mode phototherapy bacteriostatic; Nano graphene oxide.

Scheme 1

Schematic illustration of the preparation process of NGO-BSA-AIE NPs, NGO-BSA-AIE NPs for tracking bacteria and dual-mode phototherapy bacteriostatic

Fig. 1

a Size distribution and b SEM image of synthetic NGO

Fig. 2

a Absorption and emission spectra of the synthesized AIEgen. b FL spectra of the AIEgen and DCF mixture in THF/water to detect its ROS production under daylight exposures (10 mW cm⁻²) for various time period. c Aggregation-induced emission characteristics of AIEgen: FL spectra of AIEgen in different ratios of THF/water mixture (λex = 493 nm) and calculated I/I₀ ratios as a function of water fraction

Fig. 3

Characterization of NGO-BSA-AIE NPs by a DLS, b SEM imaging (Scale bars: 200 nm) and c Stability evaluation of NGO-BSA-AIE NPs within 7 days in RPMI 1640 media by DLS size monitoring

Fig. 4

a ROS production under daylight exposures (10 mW cm⁻²). b CLSM imaging of AMO^r E. coli after incubation with NGO-BSA-AIE NPs and DCF-DA under daylight irradiation for different time in the presence and absence of vitamin C. (λex = 488 nm, λem = 525 nm) Scale bars: 5 μm

Fig. 5

a Photothermal curves of different concentrations of NGO-BSA-AIE NPs under 795 nm NIR laser irradiation. NGO: 0.25, 0.5, 1.0 mg mL⁻¹; BSA: 1.0, 2.0, 4.0 mg mL⁻¹; AIE: 0.5, 10, 20 μg mL⁻¹. b The temperature rising and cooling curve of the NGO-BSA-AIE NPs with 5 times laser switch-on and switch-off treatment

Fig. 6

a CFU for AMO^r E. coli and AMO^r S. aureus of control group without any treatment, bacterial in PBS that exposed to daylight for 1 h (10 mW cm⁻²) followed by NIR irradiation for 5 min (795 nm, 2.5 W cm⁻²), NGO-BSA-AIE NPs that presented in a dark environment or irradiated with light/laser. Quatitative results of CFU of b AMO^r E. coli and c AMO^r S. aureus. Significant differences between every two groups (p < 0.05) are indicated by an asterisk (*)

Fig. 7

SEM images of AMO^r E. coli and AMO^r S. aureus treated with PBS (a, f) and NGO-BSA-AIE NPs that presented in a dark environment (b, g), irradiated with daylight (c, h), irradiated with 795 nm NIR laser (d, i) and irradiated with daylight followed by 795 nm NIR laser (e, j). Scale bars: 200 nm

Fig. 8

Intracellular distribution observed by CLSM of NGO-BSA-AIE NPs in AMO^r E. coli and AMO^r S. aureus. Scale bars: 5 μm

Fig. 9

Cell viability assay of L929 cells treated with different concentrations of AIEgen of NGO-BSA-AIE NPs