pH and reduction dual-responsive micelles based on novel polyurethanes with detachable poly(2-ethyl-2-oxazoline) shell for controlled release of doxorubicin

A pH-responsive cetuximab-conjugated DMAKO-20 nano-delivery system for overcoming K-ras mutations and drug resistance in colorectal carcinoma

Cetuximab (Cet) and oxaliplatin (OXA) are used as first-line drugs for patients with colorectal carcinoma (CRC). In fact, the heterogeneity of CRC, mainly caused by K-ras mutations and drug resistance, undermines the effectiveness of drugs. Recently, a hydrophobic prodrug, (1E,4E)-6-((S)-1-(isopentyloxy)-4-methylpent-3-en-1-yl)-5,8-dimethoxynaphthalene-1,4‑dione dioxime (DMAKO-20), has been shown to undergo tumor-specific CYP1B1-catalyzed bioactivation. This process results in the production of nitric oxide and active naphthoquinone mono-oximes, which exhibit specific antitumor activity against drug-resistant CRC. In this study, a Cet-conjugated bioresponsive DMAKO-20/PCL-PEOz-targeted nanocodelivery system (DMAKO@PCL-PEOz-Cet) was constructed to address the issue of DMAKO-20 dissolution and achieve multitargeted delivery of the cargoes to different subtypes of CRC cells to overcome K-ras mutations and drug resistance in CRC. The experimental results demonstrated that DMAKO@PCL-PEOz-Cet efficiently delivered DMAKO-20 to both K-ras mutant and wild-type CRC cells by targeting the epidermal growth factor receptor (EGFR). It exhibited a higher anticancer effect than OXA in K-ras mutant cells and drug-resistant cells. Additionally, it was observed that DMAKO@PCL-PEOz-Cet reduced the expression of glutathione peroxidase 4 (GPX4) in CRC cells and significantly inhibited the growth of heterogeneous HCT-116 subcutaneous tumors and patient-derived tumor xenografts (PDX) model tumors. This work provides a new strategy for the development of safe and effective approaches for treating CRC. STATEMENT OF SIGNIFICANCE: (1) Significance: This work reports a new approach for the treatment of colorectal carcinoma (CRC) using the bioresponsible Cet-conjugated PCL-PEOz/DMAKO-20 nanodelivery system (DMAKO@PCL-PEOz-Cet) prepared with Cet and PCL-PEOz for the targeted transfer of DMAKO-20, which is an anticancer multitarget drug that can even prevent drug resistance, to wild-type and K-ras mutant CRC cells. DMAKO@PCL-PEOz-Cet, in the form of nanocrystal micelles, maintained stability in peripheral blood and efficiently transported DMAKO-20 to various subtypes of colorectal carcinoma cells, overcoming the challenges posed by K-ras mutations and drug resistance. The system's secure and effective delivery capabilities have also been confirmed in organoid and PDX models. (2) This is the first report demonstrating that this approach simultaneously overcomes the K-ras mutation and drug resistance of CRC.

PH Responsive Polyurethane for the Advancement of Biomedical and Drug Delivery

Due to the specific physiological pH throughout the human body, pH-responsive polymers have been considered for aiding drug delivery systems. Depending on the surrounding pH conditions, the polymers can undergo swelling or contraction behaviors, and a degradation mechanism can release incorporated substances. Additionally, polyurethane, a highly versatile polymer, has been reported for its biocompatibility properties, in which it demonstrates good biological response and sustainability in biomedical applications. In this review, we focus on summarizing the applications of pH-responsive polyurethane in the biomedical and drug delivery fields in recent years. In recent studies, there have been great developments in pH-responsive polyurethanes used as controlled drug delivery systems for oral administration, intravaginal administration, and targeted drug delivery systems for chemotherapy treatment. Other applications such as surface biomaterials, sensors, and optical imaging probes are also discussed in this review.

Inhaled ciprofloxacin-loaded poly(2-ethyl-2-oxazoline) nanoparticles from dry powder inhaler formulation for the potential treatment of lower respiratory tract infections

Lower respiratory tract infections (LRTIs) are one of the fatal diseases of the lungs that have severe impacts on public health and the global economy. The currently available antibiotics administered orally for the treatment of LRTIs need high doses with frequent administration and cause dose-related adverse effects. To overcome this problem, we investigated the development of ciprofloxacin (CIP) loaded poly(2-ethyl-2-oxazoline) (PEtOx) nanoparticles (NPs) for potential pulmonary delivery from dry powder inhaler (DPI) formulations against LRTIs. NPs were prepared using a straightforward co-assembly reaction carried out by the intermolecular hydrogen bonding among PEtOx, tannic acid (TA), and CIP. The prepared NPs were characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction analysis (PXRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The CIP was determined by validated HPLC and UV spectrophotometry methods. The CIP loading into the PEtOx was between 21-67% and increased loading was observed with the increasing concentration of CIP. The NP sizes of PEtOx with or without drug loading were between 196-350 nm and increased with increasing drug loading. The in vitro CIP release showed the maximum cumulative release of about 78% in 168 h with a burst release of 50% in the first 12 h. The kinetics of CIP release from NPs followed non-Fickian or anomalous transport thus suggesting the drug release was regulated by both diffusion and polymer degradation. The in vitro aerosolization study carried out using a Twin Stage Impinger (TSI) at 60 L/min air flow showed the fine particle fraction (FPF) between 34.4% and 40.8%. The FPF was increased with increased drug loading. The outcome of this study revealed the potential of the polymer PEtOx as a carrier for developing CIP-loaded PEtOx NPs as DPI formulation for pulmonary delivery against LRTIs.

Biobased polyurethanes for biomedical applications

Polyurethanes (PUs) are a major family of polymers displaying a wide spectrum of physico-chemical, mechanical and structural properties for a large range of fields. They have shown suitable for biomedical applications and are used in this domain since decades. The current variety of biomass available has extended the diversity of starting materials for the elaboration of new biobased macromolecular architectures, allowing the development of biobased PUs with advanced properties such as controlled biotic and abiotic degradation. In this frame, new tunable biomedical devices have been successfully designed. PU structures with precise tissue biomimicking can be obtained and are adequate for adhesion, proliferation and differentiation of many cell's types. Moreover, new smart shape-memory PUs with adjustable shape-recovery properties have demonstrated promising results for biomedical applications such as wound healing. The fossil-based starting materials substitution for biomedical implants is slowly improving, nonetheless better renewable contents need to be achieved for most PUs to obtain biobased certifications. After a presentation of some PU generalities and an understanding of a biomaterial structure-biocompatibility relationship, recent developments of biobased PUs for non-implantable devices as well as short- and long-term implants are described in detail in this review and compared to more conventional PU structures.

Dual stimuli-responsive nanoplatform based on core-shell structured graphene oxide/mesoporous silica@alginate

A dual stimuli-responsive nanoplatform was rationally designed for controlled drug delivery. The nanosheets of graphene oxide (GO) were first modified with aminated mesoporous silica (NH₂-mSiO₂), and then methotrexate (MTX) was loaded into the mesopores of mSiO₂. Alginate (Alg) acted as the "gatekeeper" was then anchored to the MTX-loaded GO/NH₂-mSiO₂ by amidation reaction, achieving the encapsulation of MTX in the core-shell structured GO/mSiO₂@Alg. Due to the high pH sensitivity of amide bond and the excellent photothermal conversion ability of GO, the constructed nanoplatform could be used for pH and near-infrared (NIR) controlled delivery of MTX. The results of cell viability test demonstrate the high inhibitory rate of the dual stimuli-responsive nanoplatform toward hepatoma (HepG2) cells.

Stimuli-Responsive Micelles with Detachable Poly(2-ethyl-2-oxazoline) Shell Based on Amphiphilic Polyurethane for Improved Intracellular Delivery of Doxorubicin

Polyurethanes (PUs) have various biomedical applications including controlled drug delivery. However, the incompletely release of drug at tumor sites limits the efficiency of these drug loaded polyurethane micelles. Here we report a novel polymer poly(2-ethyl-2-oxazoline)-SS-polyurethane-SS-poly(2-ethyl-2-oxazoline) triblock polyurethane (PEtOz-PU(PTMCSS)-PEtOz). The hydrophilic pH-responsive poly(2-ethyl-2-oxazoline) was used as an end-block to introduce pH responsiveness, and the hydrophobic PU middle-block was easily synthesized by the reaction of poly (trimethylene carbonate) diol containing disulfide bonds (PTMC-SS-PTMC diol) and bis (2-isocyanatoethyl) disulfide (CDI). PEtOz-PU(PTMCSS)-PEtOz could self-assemble to form micelles (176 nm). The drug release profile of PEtOz-PU(PTMCSS)-PEtOz micelles loaded with Doxorubicin (DOX) was studied in the presence of acetate buffer (10 mM, pH 5.0) and 10 mM dithiothreitol (DTT). The results showed that under this environment, DOX-loaded polyurethane micelles could release DOX faster and more thoroughly, about 97% of the DOX was released from the DOX-loaded PEtOz-PU(PTMCSS)-PEtOz micelle. In addition, fluorescent microscopy and cell viability assays validated that the DOX-loaded polyurethane micelle strongly inhibits the growth of C6 cells, suggesting their potential as a new nanomedicine against cancer.

Paclitaxel/sunitinib-loaded micelles promote an antitumor response in vitro through synergistic immunogenic cell death for triple-negative breast cancer

Chemotherapy-induced immunogenic cell death (ICD) may offer a strategy to improve the effect of the therapeutic treatment of triple-negative breast cancer (TNBC) by eliciting broad antitumor immunity. However, chemotherapy shows a limited therapeutic effect because of multi-drug resistance and the immunosuppressive tumor microenvironment (TME) of TNBC. The unique pharmacological actions of sunitinib (SUN) indicate its possible synergies with paclitaxel (PTX) to enhance chemo-immunotherapy for TNBC. Here, we prepared a co-delivery platform composed of poly(styrene-co-maleic anhydride) (SMA) via a self-assembly process for a combination of PTX and SUN, which was able to induce a higher synergistic ICD. The nanomicellar delivery of PTX and SUN loaded at an optimal ratio of 1:5 (PTX:SUN) presented the characteristics of an appropriate particle size, long-term stability, and time sequence release which synergistically promoted the apoptosis of MDA-MB-231 tumor cells. Moreover, we demonstrated that the combination of PTX and SUN could significantly induce a synergistic effect because it promoted an ICD response, improved tumor immunogenicity, and regulated immunosuppressive factors in the TME. Overall, PTX and SUN with synergistic effects entrapped in a self-assembly nano-delivery system could offer the potential for clinical applicationof a combination chemo-immunotherapy strategy to improve the effect of the therapeutic treatment of TNBC.

Development of stimuli-responsive intelligent polymer micelles for the delivery of doxorubicin

Doxorubicin is still used as a first-line drug in current therapeutics for numerous types of malignant tumours (including lymphoma, transplantable leukaemia and solid tumour). Nevertheless, to overcome the serious side effects like cardiotoxicity and myelosuppression caused by effective doses of doxorubicin remains as a world-class puzzle. In recent years, the usage of biocompatible polymeric nanomaterials to form an intelligently sensitive carrier for the targeted release in tumour microenvironment has attracted wide attention. These different intelligent polymeric micelles (PMs) could change the pharmacokinetics process of drugs or respond in the special microenvironment of tumour site to maximise the efficacy and reduce the toxicity of doxorubicin in other tissues and organs. Several intelligent PMs have already been in the clinical research stage and planned for market. Therefore, related research remains active, and the latest nanotechnology approaches for doxorubicin delivery are always in the spotlight. Centring on the model drugs doxorubicin, this review summarised the mechanisms of PMs, classified the polymers used in the application of doxorubicin delivery and discussed some interesting and imaginative smart PMs in recent years.

pH-Responsive Artesunate Polymer Prodrugs with Enhanced Ablation Effect on Rodent Xenograft Colon Cancer

Purpose

In this study, pH-sensitive poly(2-ethyl-2-oxazoline)-poly(lactic acid)-poly(β-amino ester) (PEOz-PLA-PBAE) triblock copolymers were synthesized and were conjugated with an antimalaria drug artesunate (ART), for inhibition of a colon cancer xenograft model.

Methods

The as-prepared polymer prodrugs are tended to self-assemble into polymeric micelles in aqueous milieu, with PEOz segment as hydrophilic shell and PLA-PBAE segment as hydrophobic core.

Results

The pH sensitivity of the as-prepared copolymers was confirmed by acid-base titration with pKb values around 6.5. The drug-conjugated polymer micelles showed high stability for at least 96 h in PBS and 37°C, respectively. The as-prepared copolymer prodrugs showed high drug loading content, with 9.57%±1.24% of drug loading for PEOz-PLA-PBAE-ART4. The conjugated ART could be released in a sustained and pH-dependent manner, with 92% of released drug at pH 6.0 and 57% of drug released at pH 7.4, respectively. In addition, in vitro experiments showed higher inhibitory effect of the prodrugs on rodent CT-26 cells than that of free ART. Animal studies also demonstrated the enhanced inhibitory efficacy of PEOz-PLA-PBAE-ART2 micelles on the growth of rodent xenograft tumor.

Conclusion

The pH-responsive artesunate polymer prodrugs are promising candidates for colon cancer adjuvant therapy.

Poly(ethylene glycol)-sheddable reduction-sensitive polyurethane micelles for triggered intracellular drug delivery for osteosarcoma treatment

BACKGROUND

The survival rate of osteosarcoma therapy still lags behind overall cancer therapies due to the intrinsic or acquired drug resistance. Developing novel drug delivery systems that may overcome drug resistance would greatly facilitate osteosarcoma therapy.

METHODS

Poly(ethylene glycol) (PEG)-sheddable reduction-sensitive polyurethane (SS-PU-SS-PEG) was synthesized using a disulfide-containing polycaprolactone diol as the hydrophobic block and a cystamine-functionalized PEG as the hydrophilic block. SS-PU-SS-PEG micelles were then prepared to load the anti-tumor drug Doxorubicin (DOX) in order to achieve triggered intracellular drug delivery to improve the efficacy of osteosarcoma therapy.

RESULTS

When DOX was used as a model drug, the drug-loaded SS-PU-SS-PEG micelles were about 82∼94 nm in diameter and exhibited good stability in phosphate buffer saline (PBS). The micelles could release about 80% DOX in a quantitative fashion within 5 hours under a reductive environment. The intracellular drug release of DOX-loaded SS-PU-SS-PEG micelles increased upon incubation with Saos-2 cells in vitro. The micelles had good biocompatibility. In vitro, DOX-loaded SS-PU-SS-PEG micelles showed significant antitumor activity toward Saos-2 cells, which was close to that of free DOX. In vivo, DOX-loaded SS-PU-SS-PEG micelles exhibited better antitumor activity than free DOX.

CONCLUSION

Findings from this study suggest that the SS-PU-SS-PEG micelles could achieve well-controlled triggered drug release in a reduction environment and could therefore improve the antitumor efficacy of osteosarcoma therapies.

TRANSLATION POTENTIAL OF THIS ARTICLE

In this study we developed PEG-sheddable reduction-sensitive polyurethane micelles (SS-PU-SS-PEG), which were able to achieve well-controlled triggered release of anti-tumor drug Doxorubicin (DOX) in an intracellular reduction environment. DOX-loaded SS-PU-SS-PEG micelles markedly improved the antitumor efficacy in a Saos-2 cells-bearing xenograft tumor model. Therefore, such micelles might be used as a novel drug delivery system for osteosarcoma treatment.

Glycyrrhetinic acid modified and pH-sensitive mixed micelles improve the anticancer effect of curcumin in hepatoma carcinoma cells

Curcumin (CUR), a natural polyphenolic compound existing in plants, exhibits anticancer potential in inhibiting the growth of various types of human cancer. However, the poor aqueous solubility and low bioavailability limit its clinical applications. pH-sensitive macromolecule F68-acetal-PCL (FAP) and active targeting macromolecule F68-glycyrrhetinic acid (FGA) were designed to fabricate mixed micelles for efficient delivery of CUR. The thin film hydration method was used to prepare CUR loaded mixed (MIX/CUR) micelles. The drug loading rate (DL) of MIX/CUR micelles was 6.31 ± 0.92%, which remained stable for 15 days at 4 °C. The particle size and zeta potential of the MIX/CUR micelles were 91.06 ± 1.37 nm and -9.79 ± 0.47 mV, respectively. The MIX/CUR micelles exhibited pH sensitivity in a weak acid environment, and showed rapid particle size variation and drug release. In addition, in vitro tests demonstrated that MIX/CUR micelles induced higher cytotoxicity and apoptosis than free CUR, non-pH-sensitive F68-PCL (FBP)/CUR micelles and pH-sensitive FAP/CUR micelles in SMMC7721 and Hepa1-6 cells. Besides, mixed micelles were more effective than FBP and FAP micelles in a cell uptake experiment, which was medicated by a GA receptor. All in all, these results indicated that MIX/CUR micelles could be regarded as an ideal drug administration strategy against hepatoma carcinoma cells.