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

It remains an extreme challenge to develop multifunctional drug delivery systems with tumor specificity and a tumor microenvironment (TME) remodeling ability for achieving improved chemotherapy against malignant tumors. Herein, we report the design of diselenide-crosslinked poly(N-vinylcaprolactam) (PVCL) nanogels (NGs) co-loaded with gold (Au) nanoparticles (NPs) and methotrexate (MTX) as a multifunctional nanoplatform (for short, MTX/Au@PVCL NGs) for improved chemotherapy and computed tomography (CT) imaging of tumors. The designed MTX/Au@PVCL NGs show excellent colloidal stability under physiological conditions, while dissociating rapidly to release the incorporated Au NPs and MTX in the H2O2-abundant and slightly acidic TME. The responsive release of Au NPs and MTX effectively induces the apoptosis of cancer cells and prevents DNA replication, together contributing to the repolarization of macrophages from protumor M2-like to antitumor M1-like phenotype in vitro. The MTX/Au@PVCL NGs also enable the remodeling of tumor-associated macrophages to the M1-like phenotype in vivo in a subcutaneous mouse melanoma model, which increases the recruitment of effector T lymphocytes and reduces the content of immunosuppressive regulatory T cells to achieve synergistically enhanced antitumor efficacy when combined with MTX-mediated chemotherapy. Moreover, the MTX/Au@PVCL NGs can be used for Au-mediated CT imaging of tumors. The thus developed NG platform shows great promise as an updated nanomedicine formulation for immune modulation-enhanced tumor chemotherapy under the guidance of CT imaging.

Automated summary

In this study, a multifunctional drug delivery system was developed for improved chemotherapy against malignant tumors. The system consisted of diselenide-crosslinked poly(N-vinylcaprolactam) (PVCL) nanogels co-loaded with gold nanoparticles (Au NPs) and methotrexate (MTX). The designed nanogels showed excellent colloidal stability under physiological conditions, but rapidly released Au NPs and MTX in the tumor microenvironment. The released Au NPs and MTX induced apoptosis of cancer cells and repolarized tumor-associated macrophages from protumor M2-like phenotype to antitumor M1-like phenotype. This nanogel system also enabled CT imaging of tumors, showing great promise for immune modulation-enhanced tumor chemotherapy.