RESUMO
Conventional cancer chemotherapy regimens, albeit successful to some extent, suffer from some significant drawbacks, such as high-dose requirements, limited bioavailability, low therapeutic indices, emergence of multiple drug resistance, off-target distribution, and adverse effects. The main goal of developing implantable drug delivery systems (IDDS) is to address these challenges and maintain anti-cancer drugs directly at the intended sites of therapeutic action while minimizing inevitable side effects. IDDS possess numerous advantages over conventional drug delivery, including controlled drug release patterns, one-time drug administration, as well as loading and stabilizing poorly water-soluble chemotherapy drugs. Here, we summarized conventional and novel (three-dimensional (3D) printing and microfluidic) preparation techniques of different IDDS, including nanofibers, films, hydrogels, wafers, sponges, and osmotic pumps. These systems could be designed with high biocompatibility and biodegradability features using a wide variety of natural and synthetic polymers. We also reviewed the published data on these systems in cancer therapy with a particular focus on their release behavior. Various release profiles could be attained in IDDS, which enable predictable, adjustable, and sustained drug releases. Furthermore, multi-step or stimuli-responsive drug release could be obtained in these systems. The studies mentioned in this article have proven the effectiveness of IDDS for treating different cancer types with high prevalence, including breast cancer, and aggressive cancer types, such as glioblastoma and liver cancer. Additionally, the challenges in applying IDDS for efficacious cancer therapy and their potential future developments are also discussed. Considering the high potential of IDDS for further advancements, such as programmable release and degradation features, further clinical trials are needed to ensure their efficiency. The overall goal of this review is to expand our understanding of the behavior of commonly investigated IDDS and to identify the barriers that should be addressed in the pursuit of more efficient therapies for cancer. See also the graphical abstract(Fig. 1).
RESUMO
Background: Stimuli-responsive drug delivery systems have been proven to be a promising strategy to enhance tumor localization, overcome multidrug resistance (MDR), and reduce the side effects of chemotherapy agents. Objectives: In this study, a temperature and redox dual stimuli-responsive system using mesoporous silica nanoparticles (MSNs) for targeted delivery of doxorubicin (DOX) was developed. Methods: Mesoporous silica nanoparticles were capped with poly(N-isopropylacrylamide) (PNIPAM), a thermo-sensitive polymer, with atom transfer radical polymerization (ATRP) method, via disulfide bonds (DOX-MSN-S-S-PNIPAM) to attain a controlled system that releases DOX under glutathione-rich (GSH-rich) environments and temperatures above PNIPAM's lower critical solution temperature (LCST). Morphological and physicochemical properties of the nanoparticles were indicated using transmission electron microscopy (TEM), dynamic light scattering (DLS), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and Brunauer-Emmett-Teller (BET). The drug release tests were performed at 25°C and 41°C in the absence and presence of the DTT, and the obtained results confirmed the synergic effect of temperature and reductive agent on a dual responsive release profile with a 73% cumulative release at 41°C and reductive environment during 240 min. Results: The average loaded drug content and encapsulation efficacy were reported as 42% and 29.5% at the drug: nanoparticle ratio of 1.5: 1. In vitro cytotoxicity assays on MCF-7 cell lines indicated significant viability decreased in cells exposed to DOX-MSN-S-S-PNIPAM compared to the free drug (DOX). Conclusions: Based on the results, DOX-MSN-S-S-PNIPAM has shown much more efficiency with stimuli-responsive properties in comparison to DOX on MCF-7 cancer cell lines.
