ATP-Charged Nanoclusters Enable Intracellular Protein Delivery and Activity Modulation for Cancer Theranostics

Glucose oxidase-instructed biomineralization of calcium-based biomaterials for biomedical applications

In recent years, glucose oxidase (GOx) has aroused great research interest in the treatment of diseases related to abnormal glucose metabolisms like cancer and diabetes. However, as a kind of endogenous oxido-reductase, GOx suffers from poor stability and system toxicity in vivo. In order to overcome this bottleneck, GOx is encapsulated in calcium-based biomaterials (CaXs) such as calcium phosphate (CaP) and calcium carbonate (CaCO3) by using it as a biotemplate to simulate the natural biomineralization process. The biomineralized GOx holds improved stability and reduced side effects, due to the excellent bioactivity, biocompatibitliy, and biodegradability of CaXs. In this review, the state-of-the-art studies on GOx-mineralized CaXs are introduced with an emphasis on their application in various biomedical fields including disease diagnosis, cancer treatment, and diabetes management. The current challenges and future perspectives of GOx-mineralized CaXs are discussed, which is expected to promote further studies on these smart GOx-mineralized CaXs biomaterials for practical applications.

Review of the Delivery Kinetics of Thermosensitive Liposomes

Thermosensitive liposomes (TSL) are triggered nanoparticles that release the encapsulated drug in response to hyperthermia. Combined with localized hyperthermia, TSL enabled loco-regional drug delivery to tumors with reduced systemic toxicities. More recent TSL formulations are based on intravascular triggered release, where drug release occurs within the microvasculature. Thus, this delivery strategy does not require enhanced permeability and retention (EPR). Compared to traditional nanoparticle drug delivery systems based on EPR with passive or active tumor targeting (typically <5%ID/g tumor), TSL can achieve superior tumor drug uptake (>10%ID/g tumor). Numerous TSL formulations have been combined with various drugs and hyperthermia devices in preclinical and clinical studies over the last four decades. Here, we review how the properties of TSL dictate delivery and discuss the advantages of rapid drug release from TSL. We show the benefits of selecting a drug with rapid extraction by tissue, and with quick cellular uptake. Furthermore, the optimal characteristics of hyperthermia devices are reviewed, and impact of tumor biology and cancer cell characteristics are discussed. Thus, this review provides guidelines on how to improve drug delivery with TSL by optimizing the combination of TSL, drug, and hyperthermia method. Many of the concepts discussed are applicable to a variety of other triggered drug delivery systems.

Reactive oxygen species-responsive branched poly (β-amino ester) with robust efficiency for cytosolic protein delivery

Protein therapy targeting the intracellular machinery holds great potentials for disease treatment, and therefore, effective cytosolic protein delivery technologies are highly demanded. Herein, we developed reactive oxygen species (ROS)-degradable, branched poly(β-amino ester) (PBAE) with built-in phenylboronic acid (PBA) in the backbone and terminal-pendent arginine for the efficient cytosolic protein delivery. The PBAE could form stable and cell-ingestible nanocomplexes (NCs) with proteins via electrostatic interaction, nitrogen-boronate (N-B) coordination, and hydrogen bonding, while it can be degraded into small segments by the over-produced H₂O₂ in tumor cells to enable cytoplasmic protein release. As thus, PBAE exhibited high efficiency in delivering varieties of proteins with distinct molecular weights (12.4-430 kDa) and isoelectric points (4.7-10.5) into tumor cells, including enzymes, toxins, and antibodies. Moreover, PBAE mediated efficient delivery of saporin into tumor cells in vivo, provoking pronounced anti-tumor outcomes. This study provides a robust and versatile platform for cytosolic protein delivery, and the elaborately tailored PBAE may find promising applications for protein-based biological research and disease management. STATEMENT OF SIGNIFICANCE: Cytosolic delivery of native proteins holds great therapeutic potentials, which however, is limited by the lack of robust delivery carriers that can simultaneously feature strong protein encapsulation yet effective intracellular protein release. Herein, ROS-degradable, branched poly(β-amino ester) (PBAE) with backbone-embedded phenylboronic acid (PBA) and terminal-pendent arginine was developed to synchronize these two processes. PBA and arginine moieties allowed PBAE to encapsulate proteins via N-B coordination, electrostatic interaction, hydrogen bonding, and salt bridging, while PBA could be oxidized by over-produced H₂O₂ inside cancer cells to trigger PBAE degradation and intracellular protein release. As thus, the top-performing PBAE mediated efficient cytosolic delivery of various proteins including enzymes, toxins, and antibodies. This study provides a powerful platform for cytosolic protein delivery, and may find promising utilities toward intracellular protein therapy against cancer and other diseases such as inflammation.

Bioresponsive Polymers for Nanomedicine-Expectations and Reality!

Bioresponsive polymers in nanomedicine have been widely perceived to selectively activate the therapeutic function of nanomedicine at diseased or pathological sites, while sparing their healthy counterparts. This idea can be described as an advanced version of Paul Ehrlich’s magic bullet concept. From that perspective, the inherent anomalies or malfunction of the pathological sites are generally targeted to allow the selective activation or sensory function of nanomedicine. Nonetheless, while the primary goals and expectations in developing bioresponsive polymers are to elicit exclusive selectivity of therapeutic action at diseased sites, this remains difficult to achieve in practice. Numerous research efforts have been undertaken, and are ongoing, to tackle this fine-tuning. This review provides a brief introduction to key stimuli with biological relevance commonly featured in the design of bioresponsive polymers, which serves as a platform for critical discussion, and identifies the gap between expectations and current reality.

Metabolic intervention liposome for targeting glutamine-addiction of breast cancer

The growth and rapid proliferation of tumor cells depend on both glycolysis and glutamine metabolism, leading to metabolic compensation. Here, dual inhibition on the metabolic plasticity by Glucose oxidase and Telaglenastat loaded liposome (Lip@GOx&Tel) were studied for intervening metabolic pathway on energy and material against breast cancer. Lip@GOx&Tel targeting inhibited the two nutrient supply mechanisms employed by tumor cells, reducing the supply of ATP production and biosynthesis precursors essential necessary for tumor, thereby eliciting anti-tumor and anti-metastasis effect. Meanwhile, Lip@GOx&Tel ingeniously amplify the therapeutic effect by up-regulating ROS and down-regulating GSH to disrupt redox homeostasis, thus resulting in inspiring 82% tumor suppression rate on 4 T1 tumor model. Moreover, our study solved the limitation of combination between protein drugs and small molecule drugs in vivo by using liposome nanoparticles with clinical translation value. In short, this work provides a unique perspective of nanomedicine for treating diseases from metabolic intervention.

Engineered EGCG-Containing Biomimetic Nanoassemblies as Effective Delivery Platform for Enhanced Cancer Therapy

Nano-based immunotherapy of therapeutic biomolecules is attractive but tremendously hampered by the poor delivery efficiency. This study reports a novel delivery system of fluorinated-coordinative-epigallocatechin gallate (EGCG), referring as FEGCG/Zn, through the integration of fluorination and zinc ions (Zn²⁺ ) into EGCG. The robust therapeutics of FEGCG/Zn are measured in terms of the regulating effect on programmed cell death ligand 1 (PD-L1), the effective delivery of diverse biomolecules, and the hitchhiking ability using living cells. Taking small interfering RNA of PD-L1 (siPD-L1) and erythrocytes as an example, the fabricated biomimetic system achieves excellent siPD-L1 delivery and further improves siPD-L1 accumulation in tumors. Finally, the combination of FEGCG/Zn and siPD-L1 promotes antitumor immunotherapy through alleviation of T cells exhaustion by regulating PD-L1 expression in tumor cells. The results demonstrate that FEGCG/Zn substantially regulates PD-L1 expression and improves immune-biomolecule delivery by forming biomimetic nanoassemblies, offering a versatile platform for cancer immunotherapy.

Crosslinked Protein Delivery Strategy with Precise Activity Regulation Properties for Cancer Therapy and Gene Editing

Protein drugs hold tremendous promise for therapeutic applications due to their direct and superior pharmacological effects. However, protein drugs can be degraded in blood stream and unable to cross many physical barriers to exert therapeutic effect. Degradable synthetic crosslinking is a versatile strategy to enhance the stability of the nanoparticle in a complex physiological medium and is helpful to get through physical barriers. Herein, crosslinked polypeptide (PABP) composed of poly-amino acids including cystine, tyrosine, lysine, ketal bridge, and polyethylene glycol (PEG) is modularly explored and synthesized for protein delivery. Notably, plasma membrane V-ATPase is the particular pathway which induces the macropinocytosis of the inner peptide analogous core (PAB/protein) after the outer PEG shell disassociation at tumor intercellular sites. In addition, PABP/protein achieves proteins' activity shielding in systemic circulation and recovery in tumor cytoplasm precisely. In application, PABP/RNase-A shows satisfying tumor accumulation and antineoplastic efficacy. More importantly, PABP/Cas9 + small guide RNA displays obvious gene editing efficiency. The crosslinked protein delivery strategy not only makes the accurate protein transport and activity regulation possible but also is promising in paving the way for clinical translation of protein drugs.

Tailoring Hyperbranched Poly(β-amino ester) as a Robust and Universal Platform for Cytosolic Protein Delivery

Cytosolic protein delivery is a prerequisite for protein-based biotechnologies and therapeutics on intracellular targets. Polymers that can complex with proteins to form nano-assemblies represent one of the most important categories of materials, because of the ease of nano-fabrication, high protein loading efficiency, no need for purification, and maintenance of protein bioactivity. Stable protein encapsulation and efficient intracellular liberation are two critical yet opposite processes toward cytosolic delivery, and polymers that can resolve these two conflicting challenges are still lacking. Herein, hyperbranched poly(β-amino ester) (HPAE) with backbone-embedded phenylboronic acid (PBA) is developed to synchronize these two processes, wherein PBA enhanced protein encapsulation via nitrogen-boronate (N-B) coordination while triggered polymer degradation and protein release upon oxidation by H₂ O₂ in cancer cells. Upon optimization of the branching degree, charge density, and PBA distribution, the best-performing A2-B3-C2-S₂ -P₂ is identified, which mediates robust delivery of various native proteins/peptides with distinct molecular weights (1.6-430 kDa) and isoelectric points (4.1-10.3) into cancer cells, including enzymes, toxins, antibodies, and CRISPR-Cas9 ribonucleoproteins (RNPs). Moreover, A2-B3-C2-S₂ -P₂ mediates effective cytosolic delivery of saporin both in vitro and in vivo to provoke remarkable anti-tumor efficacy. Such a potent and universal platform holds transformative potentials for protein pharmaceuticals.

Charge reversal nano-systems for tumor therapy

Surface charge of biological and medical nanocarriers has been demonstrated to play an important role in cellular uptake. Owing to the unique physicochemical properties, charge-reversal delivery strategy has rapidly developed as a promising approach for drug delivery application, especially for cancer treatment. Charge-reversal nanocarriers are neutral/negatively charged at physiological conditions while could be triggered to positively charged by specific stimuli (i.e., pH, redox, ROS, enzyme, light or temperature) to achieve the prolonged blood circulation and enhanced tumor cellular uptake, thus to potentiate the antitumor effects of delivered therapeutic agents. In this review, we comprehensively summarized the recent advances of charge-reversal nanocarriers, including: (i) the effect of surface charge on cellular uptake; (ii) charge-conversion mechanisms responding to several specific stimuli; (iii) relation between the chemical structure and charge reversal activity; and (iv) polymeric materials that are commonly applied in the charge-reversal delivery systems.

Chondroitin sulfate-mediated albumin corona nanoparticles for the treatment of breast cancer

Chondroitin sulfate-mediated albumin corona nanoparticles were readily prepared without any chemical reaction, and their active tumor targeting and therapeutic effects were examined. Negatively charged chondroitin sulfate (CS) and positively charged doxorubicin (DOX) self-assembled into nanoparticles (CS-DOX-NPs) via electrostatic interactions. Bovine serum albumin (BSA) was then adsorbed on the surface of CS-DOX-NPs to form albumin corona nanoparticles (BC-DOX-NPs) protected from endogenous proteins. Due to the dual effect of BSA and CS, BC-DOX-NPs interacted with the gp60, SPARC and CD44 receptors on tumor cells, facilitating their rapid and efficient transcytosis and improving their accumulation and uptake within tumor tissues. The simultaneous presence of BSA and CS also allowed BC-DOX-NPs to target CD44 efficiently, leading to greater cellular uptake and cytotoxicity against 4T1 cells than CS-DOX-NPs or free DOX. Intravenous injection of BC-DOX-NPs into orthotopic 4T1 tumor-bearing mice led to greater drug accumulation at the tumor site than with CS-DOX-NPs or free DOX, resulting in significant inhibition of tumor growth and lower exposure of major organs to the drug.

Weaving Enzymes with Polymeric Shells for Biomedical Applications

Enzyme therapeutics have received increasing attention due to their high biological specificity, outstanding catalytic efficiency, and impressive therapeutic outcomes. Protecting and delivering enzymes into target cells while retaining enzyme catalytic efficiency is a big challenge. Wrapping of enzymes with rational designed polymer shells, rather than trapping them into large nanoparticles such as liposomes, have been widely explored because they can protect the folded state of the enzyme and make post-functionalization easier. In this review, the methods for wrapping up enzymes with protective polymer shells are mainly focused on. It is aimed to provide a toolbox for the rational design of polymeric enzymes by introducing methods for the preparation of polymeric enzymes including physical adsorption and chemical conjugation with specific examples of these conjugates/hybrid applications. Finally, a conclusion is drawn and key points are emphasized.

Biodegradable Multifunctional Nanotheranostic Based on Ag2S-Doped Hollow BSA-SiO2 for Enhancing ROS-Feedback Synergistic Antitumor Therapy

Stimuli-responsive silica nanoparticles are an attractive therapeutic agent for effective tumor ablation, but the responsiveness of silica nanoagents is limited by intrastimulation level and silica framework structure. Herein, a biodegradable hollow SiO₂-based nanosystem (Ag₂S-GOx@BHS NYs) is developed by a novel one-step dual-template (bovine serum albumin (BSA) and cetyltrimethylammonium bromide (CTAB)) synthetic strategy for image-guided therapy. The Ag₂S-GOx@BHS NYs can be specifically activated in the tumor microenvironment via a self-feedback mechanism to achieve reactive oxygen species (ROS)-induced multistep therapy. In response to the inherent acidity and H₂O₂ at the tumor sites, Ag₂S-GOx@BHS would accelerate the structural degradation while releasing glucose oxidase (GOx), which could efficiently deplete intratumoral glucose to copious amounts of gluconic acid and H₂O₂. More importantly, the sufficient H₂O₂ not only acts as a reactant to generate Ag⁺ from Ag₂S for metal-ion therapy and improves the oxidative stress but also combines with gluconic acid results in the self-accelerating degradation process. Moreover, the released Ag₂S nanoparticles can help the Ag₂S-GOx@BHS NYs realize the second near-infrared window fluorescence (NIR-II FL) and photoacoustic (PA) imaging-guided precise photothermal therapy (PTT). Taken together, the development of a self-feedback nanosystem may open up a new dimension for a highly effective multistep tumor therapy.

Pd@Pt-GOx/HA as a Novel Enzymatic Cascade Nanoreactor for High-Efficiency Starving-Enhanced Chemodynamic Cancer Therapy

Glucose oxidase (GOx)-mediated starvation therapy has demonstrated good application prospect in cancer treatment. However, the glucose- and oxygen-depletion starvation therapy still suffers from some limitations like low therapeutic efficiency and potential side effects to normal tissues. To overcome these disadvantages, herein a novel enzymatic cascade nanoreactor (Pd@Pt-GOx/hyaluronic acid (HA)) with controllable enzymatic activities was developed for high-efficiency starving-enhanced chemodynamic cancer therapy. The Pd@Pt-GOx/HA was fabricated by covalent conjugation of GOx onto Pd@Pt nanosheets (NSs), followed by linkage with hyaluronic acid (HA). The modification of HA on Pd@Pt-GOx could block the GOx activity, catalase (CAT)-like and peroxidase (POD)-like activities of Pd@Pt, reduce the cytotoxicity to normal cells and organs, and effectively target CD44-overexpressed tumors by active targeting and passive enhanced permeability and retention (EPR) effect. After endocytosis by tumor cells, the intracellular hyaluronidase (Hyase) could decompose the outer HA and expose Pd@Pt-GOx for the enzymatic cascade reaction. The GOx on the Pd@Pt-GOx could catalyze the oxidation of intratumoral glucose by O₂ for cancer starvation therapy, while the O₂ produced from the decomposition of endogenous H₂O₂ by the Pd@Pt with the CAT-like activity could accelerate the O₂-dependent depletion of glucose by GOx. Meanwhile, the upregulated acidity and H₂O₂ content in the tumor region generated by GOx catalytic oxidation of glucose dramatically facilitated the pH-responsive POD-like activity of the Pd@Pt nanozyme, which then catalyzed degradation of the H₂O₂ to generate abundant highly toxic ^•OH, thereby realizing nanozyme-mediated starving-enhanced chemodynamic cancer therapy. In vitro and in vivo results indicated that the controllable, self-activated enzymatic cascade nanoreactors exerted highly efficient anticancer effects with negligible biotoxicity.

GSH depletion liposome adjuvant for augmenting the photothermal immunotherapy of breast cancer

The high redox level of tumor microenvironment inhibits the oxidation treatment and the immune response. Here, we innovatively develop maleimide liposome (ML) adjuvants to promote immunogenic cell death (ICD) induction and dendritic cells (DCs) maturation by glutathione (GSH) depletion for augmenting the photothermal immunotherapy of breast cancer. The ML effectively depletes the intracellular GSH and up-regulates reactive oxygen species (ROS) in both tumor cells and DCs. In tumor cells, the ROS boosted the ABTS·⁺ production to activate photothermal-induced ICD. In DCs, it relieved the immunosuppression, promoting DC maturation (57%) and antigen presenting. As a result of the ML assistant, the therapeutic systems improved the infiltration of CD8⁺ T cells to 53% in tumor tissues, eliciting strong abscopal effect and antimetastasis effect. The MLs were believed to be a superior candidate of adjuvants for enhancing immune response and cancer therapeutic efficacy.

Efficient and targeted chemo-gene delivery with self-assembled fluoro-nanoparticles for liver fibrosis therapy and recurrence

The treatment options of liver fibrosis remain limited except for liver transplantation due to the complexity and slow development in its progression. Besides, liver fibrosis recurrence and intervention time have not been reported as significant indicators to affect the anti-fibrotic efficacy of tested drugs/strategies. Herein, a novel fluoropolymer is developed to achieve high drug loading of sorafenib and efficient delivery of miR155 inhibitor (anti-miR155) for dual-targeting of hepatic stellate cells (HSCs) and kupffer cells (KCs), and we report a detailed plan on the design of treatment regimen to reveal the relationship between chemogene therapy, intervention time and fibrosis recurrence. Such a combined chemo-gene therapy of sorafenib and anti-miR155 can achieve superior therapeutic efficiency by polarizing the pro-inflammatory M1 to anti-inflammatory M2 of KCs and inhibiting the proliferation of HSCs. Importantly, efficacy and recurrence prevention of chemogene therapy earlier in the liver fibrosis will be more effective than the treatment at later stage. In conclusion, this work proposes a novel strategy to improve the efficacy and prevent recurrence of liver fibrosis by dual-regulating of KCs and HSCs, and emphasizes the importance of therapy earlier in the treatment of liver fibrosis.

Intracellular Ca2+ Cascade Guided by NIR-II Photothermal Switch for Specific Tumor Therapy

Currently, patients receiving cancer treatments routinely suffer from distressing toxic effects, most originating from premature drug leakage, poor biocompatibility, and off-targeting. For tackling this challenge, we construct an intracellular Ca2+ cascade for tumor therapy via photothermal activation of TRPV1 channels. The nanoplatform creates an artificial calcium overloading stress in specific tumor cells, which is responsible for efficient cell death. Notably, this efficient treatment is activated by mild acidity and TRPV1 channels simultaneously, which contributes to precise tumor therapy and is not limited to hypoxic tumor. In addition, Ca2+ possesses inherent unique biological effect and normal cells are more tolerant of the undesirable destructive influence than tumor cells. The Ca2+ overload leads to cell death due to mitochondrial dysfunction (upregulation of Caspase-3, cytochrome c, and downregulation of Bcl-2 and ATP), and in vivo, the released photothermal CuS nanoparticles allow an enhanced 3D photoacoustic imaging and provide instant diagnosis.