Delivery of therapeutics into the solid tumor microenvironment is a major challenge for cancer nanomedicine. Administration of certain exogenous enzymes which deplete tumor stromal components has been proposed as a method to improve drug delivery. Here we present a protein-free collagen depletion strategy for drug delivery into solid tumors, based on activating endogenous matrix metalloproteinases (MMP-1 and -2) using nitric oxide (NO). Mesoporous silica nanoparticles (MSN) were loaded with a chemotherapeutic agent, doxorubicin (DOX) as well as a NO donor (S-nitrosothiol) to create DN@MSN. The loaded NO results in activation of MMPs which degrade collagen in the tumor extracellular matrix. Administration of DN@MSN resulted in enhanced tumor penetration of both the nanovehicle and cargo (DOX), leading to significantly improved antitumor efficacy with no overt toxicity observed.

Photodynamic therapy (PDT) of cancer is limited by tumor hypoxia. Platinum nanoparticles (nano-Pt) as a catalase-like nanoenzyme can enhance PDT through catalytic oxygen supply. However, the cytotoxic activity of nano-Pt is not comprehensively considered in the existing methods to exert their multifunctional antitumor effects. Here, nano-Pt are loaded into liposomes via reverse phase evaporation. The clinical photosensitizer verteporfin (VP) is loaded in the lipid bilayer to confer PDT activity. Murine macrophage cell membranes are hybridized into the liposomal membrane to confer biomimetic and targeting features. The resulting liposomal system, termed "nano-Pt/VP@MLipo," is investigated for chemophototherapy in vitro and in vivo in mouse tumor models. At the tumor site, oxygen produced by nano-Pt catalyzation improves the VP-mediated PDT, which in turn triggers the release of nano-Pt via membrane permeabilization. The ultrasmall 3-5 nm nano-Pt enables better penetration in tumors, which is also facilitated by the generated oxygen gas, for enhanced chemotherapy. Chemophototherapy with a single injection of nano-Pt/VP@MLipo and light irradiation inhibits the growth of aggressive 4T1 tumors and their lung metastasis, and prolongs animal survival without overt toxicity.

Liposomal drug delivery for cancer therapy can be limited due to drug leakage in circulation. Here, we develop a new method to enhance the stability of actively loaded liposomal doxorubicin (DOX) through embedding a stiff nanobowl in the liposomal water cavity. Nanobowl-supported liposomal DOX (DOX@NbLipo) resists the influence of plasma protein and blood flow shear force to prevent drug leakage. This approach yields improved drug delivery to tumor sites and enhanced antitumor efficacy. Compared to alternative methods of modifying liposome surface and composition for stability, this approach designs a physical support for an all-aqueous nanoliposomal cavity. Nanobowl stabilization of liposomes is a simple and effective method to improve carrier stability and drug delivery.

Chemoresistance conferred by leukemia propagating cells (LPCs) in a therapy‐induced niche (TI‐niche) within the bone marrow is one of the main obstacles in leukemia treatment. Effective approaches to circumvent the TI‐niche protection and to eliminate the resident LPCs remain to be exploited. Here, developed is a niche‐targeted nanosystem using leukemic cell membrane‐coated mesoporous silica nanoparticles (DAazo@CMSN) for co‐delivering daunorubicin for leukemia cell chemotherapy and a TGFβRII neutralizing antibody (aTGFβRII) to block niche signaling. DAazo@CMSN effectively targets the TI‐niche. Through an azobenzene‐based hypoxia‐responsive linker, sequential delivery of the two active molecules overcomes niche‐mediated chemoresistance, attenuates systemic burden, and prolongs survival in a mouse model of leukemia. This work demonstrates a proof‐of‐principle for biomimetic and microenvironment‐activated multiplexed nanoparticulate drug delivery strategies for overcoming therapy‐induced chemoresistance in leukemia.

In view of the multiple pathological hallmarks of tumors, nanosystems for the sequential delivery of various drugs whose targets are separately located inside and outside tumor cells are desired for improved cancer therapy. However, current sequential delivery is mainly achieved through enzyme‐ or acid‐dependent degradation of the nanocarrier, which would be influenced by the heterogeneous tumor microenvironment, and unloading efficiency of the drug acting on the target outside tumor cells is usually unsatisfactory. Here, a light‐triggered sequential delivery strategy based on a liposomal formulation of doxorubicin (DOX)‐loaded small‐sized polymeric nanoparticles (DOX‐NP) and free sunitinib in the aqueous cavity, is developed. The liposomal membrane is doped with photosensitizer porphyrin–phospholipid (PoP) and hybridized with red blood cell membrane to confer biomimetic features. Near‐infrared light‐induced membrane permeabilization triggers the “ultrafast” and “thorough” release of sunitinib (100% release in 5 min) for antiangiogenic therapy and also myeloid‐derived suppressor cell (MDSC) inhibition to reverse the immunosuppressive tumor environment. Subsequently, the small‐sized DOX‐NP liberated from the liposomes is more easily uptaken by tumor cells for improved immunogenic chemotherapy. RNA sequencing and immune‐related assay indicates therapeutic immune enhancement. This light‐triggered sequential delivery strategy demonstrates the potency in cancer multimodal therapy against multiple targets in different spatial positions in tumor microenvironment.

Metal‐phenolic networks (MPNs) are an emerging class of supramolecular surface modifiers with potential use in various fields including drug delivery. Here, the development of a unique MPN‐integrated core‐satellite nanosystem (CS‐NS) is reported. The “core” component of CS‐NS comprises a liposome loaded with EDTA (a metal ion chelator) in the aqueous core and DiR (a near‐infrared photothermal transducer) in the bilayer. The “satellite” component comprises mesoporous silica nanoparticles (MSNs) encapsulating doxorubicin and is coated with a Cu2+‐tannic acid MPN. Liposomes and MSNs self‐assemble into the CS‐NS through adhesion mediated by the MPN. When irradiated with an 808 nm laser, CS‐NS liberated the entrapped EDTA, leading to Cu2+ chelation and subsequent disassembly of the core‐satellite nanostructure. Photo‐conversion from the large assembly to the small constituent particles proceeded within 5 min. Light‐triggered CS‐NS disassembly enhanced the carrier and cargo penetration and accumulation in tumor spheroids in vitro and in orthotopic murine mammary tumors in vivo. CS‐NS is long circulating in the blood and conferred improved survival outcomes to tumor‐bearing mice treated with light, compared to controls. These results demonstrate an MPN‐integrated multistage nanosystem for improved solid tumor treatment.

Abstract:In this study, polyelectrolyte multilayers were fabricated on a polystyrene (PS) plate using a Layer-by-Layer (LbL) self-assembly technique. The resulting functional platform showed improved performance compared with conventional enzyme-linked immunosorbent assay (ELISA) systems. Poly(diallyldimethylammonium chloride) (PDDA) and poly(acrylic acid) (PAA) were used as cationic and anionic polyelectrolytes. On the negatively-charged (PDDA/PAA) 3 polyelectrolyte multilayers the hydrophilic PAA surface could efficiently decrease the magnitude of the noise signal, by inhibiting nonspecific adsorption even without blocking reagent adsorption. Moreover, the (PDDA/PAA) 3 substrate covalently immobilized the primary antibody, greatly increasing the amount of primary antibody adsorption and enhancing the specific detection signal compared with a conventional PS plate. The calibration curve of the (PDDA/PAA) 3 substrate showed a wide linear range, for concentrations from 0.033 to 33 nM, a large specific signal change, and a detection limit of 33 pM, even though the conventional blocking reagent adsorption step was omitted. The (PDDA/PAA) 3 substrate provided a high-performance ELISA system with a simple fabrication process and high sensitivity; the system presented here shows potential for a variety of immunosensor applications.

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