Self-Assembled Inhalable Immunomodulatory Silk Fibroin Nanocarriers for Enhanced Drug Loading and Intracellular Antibacterial Activity

Abstract

In this study, a pH-induced self-assembly-based method has been developed to form silk fibroin nanoparticles (SFN-2) with a higher drug loading capacity (21.0 ± 2.1%) and cellular uptake than that of silk fibroin particles produced by a conventional desolvation method (SFN-1). Using the self-assembly method, rifampicin-encapsulated silk fibroin nanoparticles (R-SFN-2) were prepared with a size of 165 ± 38 nm at an optimum pH of 3.8. In silico analysis reveals that at acidic pH, the amino acid side chain charge neutralization of acidic residues, especially GLU64, promotes the formation of additional favorable interactions between the silk fibroin and the drug. The SFN-2 also possess a good aerosol property with a mass median aerodynamic diameter of 3.82 ± 0.71 μm and fine particle fraction of 64.0 ± 1.4%. These SFN-2 particles were selectively endocytosed by macrophages through clathrin- and caveolae-mediated endocytosis with a higher uptake efficiency (66.2 ± 2.1%) and were found to exhibit a sustained drug release in the presence of macrophage intracellular lysates. The cytokine and biomarker expression analyses revealed that SFN-2 could exhibit an immunomodulatory effect by polarizing the macrophages to an initial M1 phase and later M2 phase. Further, R-SFN-2 also exhibited an enhanced and sustained intracellular antibacterial activity against Mycobacterium smegmatis-infected macrophages than free rifampicin. Thus, the self-assembled silk fibroin particles with immunomodulatory action combined with a good aerosol and intracellular drug release property can be an attractive choice as a carrier for developing pulmonary drug delivery systems.

Stimuli‐responsive silk fibroin for on‐demand drug delivery

“…43 However, it has been shown that macrophages are able to polarize toward anti-inflammatory (M2) type, and this type of immune response is beneficial for a variety of applications. 44 In particular, it was also reported that following exposure to SF nanoparticles, macrophages became M1 inflammatory within 6 h and M2 antiinflammatory within 24 h (Figure 8). Additionally, SF modulates the inflammatory response by reducing Il-18, Il-1β, iNOS, and COX-2, which encodes proinflammatory mediators.…”

“…This leads to chronic inflammation and further causes macrophage polarization 43 . However, it has been shown that macrophages are able to polarize toward anti‐inflammatory (M2) type, and this type of immune response is beneficial for a variety of applications 44 . In particular, it was also reported that following exposure to SF nanoparticles, macrophages became M1 inflammatory within 6 h and M2 anti‐inflammatory within 24 h (Figure 8).…”

“…(v) Anti-inflammatory cytokine expression profiles upon exposure to SFN2. Reproduced with permission 44. Copyright 2022, American Chemical Society.F I G U R E 9 (A) Schematic illustration of (i) the preparation process of functionalized silk fibroin nanoparticles, (ii) in vitro cumulative drug release profiles in buffer solutions with different pH values and (iii) GSH concentrations.…”

Progress in silk and silk fiber-inspired polymeric nanomaterials for drug delivery

“…Frontiers in Chemical Engineering frontiersin.org organic solvent desolvation (Hasanzadeh et al, 2020;Rezaei et al, 2020;Zahedi et al, 2021), salting out (Song et al, 2019), and microfluidic devices (Shimanovich et al, 2017;Matthew et al, 2020;Vargas Montoya et al, 2020;Matthew et al, 2022;Tomeh et al, 2022) (Table 1). Control of particle size and material properties to enhance cell material interaction (Xiao et al, 2022) and to optimize non-systemic delivery routes has been established (Takeuchi et al, 2019;Yang et al, 2019;Chung et al, 2022;Mitra et al, 2022).…”

Diselenide-crosslinked nanogels laden with gold nanoparticles and methotrexate for immunomodulation-enhanced chemotherapy and computed tomography imaging of tumors

“…Another advantage of nano-based drug delivery systems is that some nanocarriers themselves have favorable modulatory functions targeting the TAMs to reverse the immunosuppression of TME, so as to synergistically improve the effect of chemotherapy. 45,46 Moreover, many hybrid nanosystems incorporated with metal or metal ions enable clinical tumor imaging along with effective therapy. For example, gold (Au)-based nanomaterials have long be applied as an excellent computed tomography (CT) imaging agent 47 due to their excellent X-ray absorption property, and have also been used to trigger the M1 polarization of TAMs.…”