Development of Rifampicin-Indocyanine Green-Loaded Perfluorocarbon Nanodroplets for Photo-Chemo-Probiotic Antimicrobial Therapy

Abstract

Acne vulgaris, generally resulted from overgrowth of Propionibacterium acnes (P. acnes), is one of the most difficult-to-treat facial dermatoses and more than 90% of adolescents experienced the disease worldwide. Because the innate non-lymphoid immune system cannot effectively eliminate excessive P. acnes from the skin surface, so far the therapy of acne vulgaris is still mainly dependent on antibiotic treatment. However, long-term or overdose of antibiotics may initiate microbial drug resistance and/or generate unexpected side effects that seriously hamper the use of antibiotics in the clinic. To overcome the aforementioned challenges, the novel rifampicin (RIF)-indocyanine green (ICG)-loaded perfluorocarbon (PFC) nanodroplets (RIPNDs) that may offer combined photo-, chemo-, and probiotic efficacies to P. acnes eradication were developed in this study. The RIPND was first characterized as a sphere-like nanoparticle with surface charge of −20.9 ± 2.40 mV and size of 240.7 ± 6.73 nm, in which the encapsulation efficiencies of RIF and ICG were 54.0 ± 10.5% and 95.0 ± 4.84%, respectively. In comparison to the freely dissolved ICG, the RIPNDs conferred an enhanced thermal stability to the entrapped ICG, and were able to provide a comparable hyperthermia effect and markedly increased production of singlet oxygen under near infrared (NIR; 808 nm, 6 W/cm2) exposure. Furthermore, the RIPNDs were able to induce fermentation of S. epidermidis but not P. acnes, indicating that the RIPNDs may serve as a selective fermentation initiator for the target probiotics. Based on the microbial population index analyses, P. acnes with 1 × 106 cells/mL can be completely eradicated by 12-h co-culture with S. epidermidis fermentation products followed by treatment of RIPNDs (≥20-μM ICG/3.8-μM RIF) + NIR for 5 min, whereby the resulted microbial mortality was even higher than that caused by using 16-fold enhanced amount of loaded RIF alone. Overall these efforts show that the RIPNDs were able to provide improved ICG stability, selective fermentability to S. epidermidis, and enhanced antimicrobial efficacy compared to equal dosage of free RIF and/or ICG, indicating that the developed nanodroplets are highly potential for use in the clinical anti-P. acne treatment with reduced chemotoxicity.

Novel Rifampicin and Indocyanine Green Co-Loaded Perfluorocarbon Nanodroplets Provide Effective In Vivo Photo–Chemo–Probiotic Antimicrobility against Pathogen of Acne Vulgaris Cutibacterium acnes

“…Figure 1 A shows the theoretical double-layer structure of the RIPND and indicates the location of each component, including PFOB, ICG, and RIF inside the nanodroplet. Such double-layer configuration was formed based on the continuous/discontinuous phase allocation of water and PFC during the twice emulsification processes reported previously [ 31 ]. The green-to-orange emulsified appearance of the RIPNDs ( Figure 1 B(a) illustrates the existence of ICG and RIF in the nanodroplets compared to the milk-like blank PFC emulsions ( Figure 1 B(b).…”

“…Moreover, the antibacterial effectiveness achieved by RIPNDs + NIR can be further enhanced by pretreatment of C. acnes in FPM (i.e., FPM + RIPNDs + NIR). In this animal study, the FPM was used to mimic the hypothetic probiotic effect on human body, since the S. epidermidis are intrinsically distributed on the human skin surface and can be rapidly fermented due to presence of RIPNDs as reported previously [ 31 ]. Based on the MPI analysis ( Figure 5 B), the subcutaneous C. acnes with 4 h pretreatment of FPM, followed by RIPNDs + NIR, suffered a 40% ( p < 0.05) higher death rate compared with those treated by RIPNDs + NIR, indicating that the FPM/probiotics played an adjuvant but significant role in the RIPND-mediated anti– C. acnes treatment.…”

“…The RIPNDs were manufactured through two emulsification processes, as reported previously [ 31 ]. In brief, RIF (0.04 wt.%) and ICG (0.1 wt.%), in 500 μL methanol, were first mixed with perfluorooctyl bromide (PFOB) containing polyethoxylated fluorosurfactant in 2% (w/w) at ambient temperature.…”

“…To incorporate the merits of each approach without aforementioned drawbacks, we previously developed a new type of nanometer-sized double-layer perfluorocarbon (PFC) nanocarrier encapsulated with rifampicin (RIF) and ICG, named rifampicin (RIF)-ICG-loaded PFC nanodroplets (RIPNDs), and preliminarily demonstrated their multi-bactericidal effect, including chemical (antibiotics), photo (photothermal and photodynamic), and probiotic antimicrobility against C. acnes in vitro [ 31 ]. Based on the data obtained in the previous study, the RIPNDs were able to (1) significantly improve the thermal stability of the entrapped ICG; (2) generate a tremendously increased amount of singlet oxygen upon NIR exposure compared with that produced by equal amount of ICG; and (3) selectively increase fermentation rate of S. epidermidis , therefore showing an enhanced antibacterial efficacy against C. acnes compared with RIF alone.…”

Bio-Functional Textiles: Combining Pharmaceutical Nanocarriers with Fibrous Materials for Innovative Dermatological Therapies

“…They have been proposed for local delivery of antimicrobial drugs for treatment of cutaneous infectious diseases. Rifampicin-indocyanine green-loaded perfluorocarbon (PFC) nanodroplets were developed as combined photo-chemo-probiotic therapeutics for the treatment of dermatoses caused by P. acnes infection [127]. The combination of vancomycin-loaded NBs with ultrasound was studied to enhance drug penetration through skin by sonophoresis and trigger drug release at the site of infection [128].…”