Carrier-free chemo-phototherapeutic nanomedicines with endo/lysosomal escape function enhance the therapeutic effect of drug molecules in tumors

Carrier-free nanomedicines offer advantages of extremely high drug loading capacity (>80%), minimal non-drug constituent burden, and facile preparation processes. Numerous studies have proved that multimodal cancer therapy can enhance chemotherapy efficiency and mitigate multi-drug resistance (MDR) through synergistic therapeutic effects. Upon penetration into the tumor matrix, nanoparticles (NPs) are anticipated to be uptaken by cancer cells, primarily through clathrin-meditated endocytosis pathways, leading to their accumulation in endosomes/lysosomes within cells. However, endo/lysosomes exhibit a highly degradative environment for organic NPs and drug molecules, often resulting in treatment failure. Hence, this study designed a lysosomal escape mechanism with carrier-free nanomedicine, combining the chemotherapeutic drug, curcumin (Cur), and the photothermal/photodynamic therapeutic drug, indocyanine green (ICG), for synergistic cancer treatment (ICG-Cur NPs) via a facile preparation process. To facilitate endo/lysosomal escape, ICG-Cur NPs were modified with metal-phenolic networks (MPNs) of different thickness. The results indicate that a thick MPN coating promotes rapid endo/lysosomal escape of ICG-Cur NPs within 4 h and enhances the photothermal conversion efficiency of ICG-Cur NPs by 55.8%, significantly improving anticancer efficacy in both chemo- and photo-therapies within 3D solid tumor models. This finding underscores the critical role of endo/lysosomal escape capacity in carrier-free drug NPs for therapeutic outcomes and offers a facile solution to achieve it.

Mitochondrial Targeted Thermosensitive Nanocarrier for Near-Infrared-Triggered Precise Synergetic Photothermal Nitric Oxide Chemotherapy

Nitric oxide (NO) intervenes, that is, a potential treatment strategy, and has attracted wide attention in the field of tumor therapy. However, the therapeutic effect of NO is still poor, due to its short half-life and instability. Therapeutic concentration ranges of NO should be delivered to the target tissue sites, cell, and even subcellular organelles and to control NO generation. Mitochondria have been considered a major target in cancer therapy for their essential roles in cancer cell metabolism and apoptosis. In this study, mesoporous silicon-coated gold nanorods encapsulated with a mitochondria targeted and the thermosensitive lipid layer (AuNR@MSN-lipid-DOX) served as the carrier to load NO prodrug (BNN6) to build the near-infrared-triggered synergetic photothermal NO-chemotherapy platform (AuNR@MSN(BNN6)-lipid-DOX). The core of AuNR@MSN exhibited excellent photothermal conversion capability and high loading efficiency in terms of BNN6, reaching a high value of 220 mg/g (w/w), which achieved near-infrared-triggered precise release of NO. The outer biocompatible lipid layer, comprising thermosensitive phospholipid DPPC and mitochondrial-targeted DSPE-PEG2000-DOX, guided the whole nanoparticle to the mitochondria of 4T1 cells observed through confocal microscopy. In the mitochondria, the nanoparticles increased the local temperature over 42 °C under NIR irradiation, and a high NO concentration from BNN6 detected by the NO probe and DSPE-PEG2000-DOX significantly inhibited 4T1 cancer cells in vitro and in vivo under the synergetic photothermal therapy (PTT)-NO therapy-chemotherapy modes. The built NIR-triggered combination therapy nanoplatform can serve as a strategy for multimodal collaboration.

Multivalent Polypeptide and Tannic Acid Cooperatively Iron-Coordinated Nanohybrids for Synergistic Cancer Photothermal Ferroptosis Therapy

Owing to having a unique mechanism to kill cancer cells via the membrane accumulation of lipid peroxide (LPO) and the downregulation of glutathione peroxidase-4 (GPX-4), the ferroptosis therapy (FT) of tumors based on the Fenton reaction of iron nanoparticles has been receiving much attention in the past decade; however, there are some hurdles including the uncontrollable release of iron ions, slower kinetics of the intracellular Fenton reaction, and poor efficacy of FT that need to be overcome. Considering cooperative coordination of a multivalent thiol-pendant polypeptide ligand with iron ions, we put forward a facile strategy for constructing the iron-coordinated nanohybrid of methacryloyloxyethyl phosphorylcholine-grafted polycysteine/iron ions/tannic acid (i.e., PCFT), which could deliver a higher concentration of iron ions into cells. The dynamic and unsaturated coordination in PCFT is favorable for the intracellular stimuli-triggered release and fast Fenton reaction to realize efficient FT, while its intrinsic photothermia would boost the Fenton reaction to induce a synergistic effect between FT and photothermal therapy (PTT). Both immunofluorescence analyses of reactive oxygen species (ROS) and LPO confirmed that the intracellular Fenton reaction resulted in efficient FT, during which process the photothermia greatly boosted ferroptosis, and the Western blot assay corroborated that the expression level of GPX-4 was downregulated by FT and highly degraded by the photothermia to induce synergistic PTT-FT in vitro. Excitingly, by a single intravenous dose of PCFT plus one NIR irradiation, in vivo PTT-FT treatment completely eradicated 4T1 tumors without skin scar and tumor recurrence for 16 days, demonstrating prominent antitumor efficacy, as evidenced by the GPX-4, H&E, and TUNEL assays.

Synthesis of multiple stimuli-responsive degradable block copolymers via facile carbonyl imidazole-induced postpolymerization modification

A robust approach that centers on carbonyl imidazole chemistry was used to synthesize a triple-stimuli-responsive degradable block copolymer labeled with acetal, disulfide, and o-nitrobenzyl groups exhibiting acid, reduction, and light responses.

Nanomedicine potentiates mild photothermal therapy for tumor ablation

The booming photothermal therapy (PTT) has achieved great progress in non-invasive oncotherapy, and paves a novel way for clinical oncotherapy. Of note, mild temperature PTT (mPTT) of 42–45 °C could avoid treatment bottleneck of the traditional PTT, including nonspecific injury to normal tissues, vasculature and host antitumor immunity. However, cancer cells can resist mPTT via heat shock response and autophagy, thus leading to insufficient mPTT monotherapy to ablate tumor. To overcome the deficient antitumor efficacy caused by thermo-resistance of cancer cells and mono mPTT, synergistic therapies towards cancer cells have been conducted with mPTT. This review summarizes the recent advances in nanomedicine-potentiated mPTT for cancer treatment, including strategies for enhanced single-mode mPTT and mPTT plus synergistic therapies. Moreover, challenges and prospects for clinical translation of nanomedicine-potentiated mPTT are discussed.

In vivo metabolizable branched poly(ester amide) based on inositol and amino acids as a drug nanocarrier for cancer therapy

Amino acid-based poly(ester amide) (PEA) has been utilized for various biomedical applications due to its tunable mechanical properties, good biocompatibility, and biodegradability. However, bioactive components have rarely been incorporated into the PEA structure, and there has been no systematic investigation of amino acid-based PEAs with branched structures. Herein, an in vivo metabolizable branched poly(ester amide) (BPEA) was synthesized from inositol (a natural growth factor) and amino acids for drug delivery in cancer therapy. The bioactive components, inositol, arginine, and phenylalanine, could improve the biocompatibility of the BPEA nanocarrier, and convert into other valuable biomolecules (phosphatidylinositol for cell signaling, functional protein, or other amino acids including ornithine, citrulline, and tyrosine) after accomplishing drug delivery and biodegradation. Paclitaxel (PTX) was encapsulated into BPEA nanocarriers to formulate drug-loaded BPEA nanoparticles (BPEA@PTX NPs). In vitro results indicated that BPEA@PTX NPs had a sub 100 nm size and could effectively inhibit the growth and migration of cancer cells. In vivo experiments further demonstrated significant suppression of tumor size compared with that with free PTX. Both in vitro and in vivo results confirmed the superior biosafety of BPEA, indicating that BPEA exhibits excellent biocompatibility and considerable potential as a drug carrier.

Ultrasmall Zwitterionic Polypeptide-Coordinated Nanohybrids for Highly Efficient Cancer Photothermal Ferrotherapy

Ferroptosis therapy (FT) based on the Fenton reaction of ferrous nanoparticles has been becoming a unique strategy for cancer treatment; however, current ferrous nanoparticles suffer from slower Fenton reaction kinetics, lower ferroptosis efficacy, and long-term toxicity, so it is urgent to construct biocompatible ferrous nanomaterials with highly efficient Fenton reaction activity for cancer FT. Inspired by single-atom catalysis and size-determined tumor penetration, we conceived an innovative strategy for constructing ultrasmall zwitterionic polypeptide-coordinated nanohybrids of PCGA@FeNP with about 6 nm by utilizing thiol/hydroxyl-iron cooperative coordination chemistry. The ultrasmall size, unsaturated ferrous coordination, and intracellular acidic pH could accelerate the Fenton reaction, thus boosting the efficacy of ferroptosis. Moreover, those coordinated nanohybrids exhibited prominent photothermia with 59.5% conversion efficiency, further accelerating the Fenton reaction and inducing a synergistic effect between FT and photothermal therapy (PTT). In vitro and in vivo GPX-4 expression ascertained that PCGA@FeNP indeed induced effective FT and synergistic FT-PTT. Remarkably, in vivo FT-PTT completely ablated 4T1 solid tumors by one treatment, presenting outstanding and synergistic antitumor efficacy via the photothermia-boosted ferroptosis and apoptosis pathways. This work supplies a practicable strategy to fabricate ultrasmall zwitterionic coordination nanohybrids for highly efficient cancer FT and FT-PTT theranostics with potential clinical transitions.

A zwitterionic polypeptide nanocomposite with unique NIR-I/II photoacoustic imaging for NIR-I/II cancer photothermal therapy

The second near infrared photoacoustic imaging (NIR-II PAI) and photothermal therapy (NIR-II PTT) have attracted wide interest in cancer theranostics because of maximum permission exposure (MPE), deep penetration, and lower scattering and background noise compared to NIR-I counterparts; however, it is imperative to develop biocompatible nanomaterials having NIR-II response. By utilizing multivalent Au-S coordination bonds, we constructed a zwitterionic polypeptide nanocomposite of PMC@AuNP with a suitable size of 48 ± 2 nm, which possessed a strong and broad absorbance at 650-1100 nm and an excellent photothermal conversion efficiency of 49.5%. In vitro biological studies demonstrated that NIR-II PTT within MPE was more effective than NIR-I PTT beyond MPE. Along with X-ray computed tomography and photothermal imaging functions, PMC@AuNP in vivo presented unique NIR-I/II PAI with 2.6-5.9 times signal enhancement compared to the contrast. By single dose and NIR-II irradiation (1064 nm, 1 W cm-2, 10 min), NIR-II PTT within MPE completely eradicated MCF-7 tumors without tissue damage and tumor recurrence within 24 days, inducing a better antitumor efficacy than NIR-I PTT beyond MPE. Importantly, this study provides an innovative method for the fabrication of biocompatible zwitterionic polypeptide nanocomposites with unique NIR-I/II PAI and NIR-II PTT attributes, thus holding great potential for precise cancer theranostics and further clinical transitions.