Active Targeting of the Nucleus Using Nonpeptidic Boronate Tags

Nuclear-Targeted Material Enabled Intranuclear MicroRNA Imaging for Tracking Gene Editing Process

Gene editing technology based on clustered regularly interspaced short palindromic repeats/associated protein (CRISPR/Cas) systems serves as an efficient tool in cancer therapy. Tracking the gene editing process can help identify the progress of cancer treatment. However, existing techniques for monitoring the gene editing process rely on lysed cells, which can not reflect the dynamic changes of nucleic acid in living cells. It urgently needs in situ and real-time imaging technologies to track the gene editing process at a living single-cell level more effectively and precisely. Here, we reported a highly efficient nuclear-targeted material, phenylboronic acid modified linear PEI (LPBA), for loading gene editing plasmids and fluorescent probes to track gene editing processes of microRNA. Based on LPBA, we achieved efficient intranuclear microRNA imaging at the living cell level, reaching 32.4-fold higher than the linear PEI (LPEI) delivery system, which facilitated further sensitive monitoring of the gene editing process both in living cells and in vivo. Meanwhile, this efficient gene-editing and real-time detection technique could be extended to screening effective gene-editing plasmids. Such LPBA-based imaging technology extended the imaging area of microRNA and offered new insight in the field of gene editing and nucleic acid detection.

Self-Assembly of Noncanonical Peptides: A New Frontier in Cancer Therapeutics and Beyond

In addition to the 20 standard amino acids that form the building blocks of proteins, nature employs alternative amino acids to create specialized "noncanonical peptides." These unique peptides, found in organisms from bacteria to humans, often exhibit unconventional structures and functionalities, playing critical roles in modulating cellular processes, particularly as antibiotics. Their potential has attracted significant interest for designing novel functional materials based on noncanonical peptides. This review highlights recent advances in the generation and application of noncanonical peptide assemblies. It begins with a definition of noncanonical peptides, including classic examples that showcase their distinct structures and useful biological activities. Then the applications of noncanonical peptide assemblies in developing anticancer therapeutics are discussed, focusing on recent and representative studies that demonstrate their efficacy and versatility in targeting tumor cells. Beyond oncology, it is explored how noncanonical peptide assemblies have been utilized in biomaterials, regenerative medicine, molecular imaging and catalysis. Finally, perspectives are offered on future directions in this rapidly evolving field, emphasizing exciting opportunities and remaining challenges that will drive continued innovation in designing and applying noncanonical peptide-based assemblies.

Emerging magic bullet: subcellular organelle-targeted cancer therapy

The therapeutic efficacy of anticancer drugs heavily relies on their concentration and retention at the corresponding target site. Hence, merely increasing the cellular concentration of drugs is insufficient to achieve satisfactory therapeutic outcomes, especially for the drugs that target specific intracellular sites. This necessitates the implementation of more precise targeting strategies to overcome the limitations posed by diffusion distribution and nonspecific interactions within cells. Consequently, subcellular organelle-targeted cancer therapy, characterized by its exceptional precision, have emerged as a promising approach to eradicate cancer cells through the specific disruption of subcellular organelles. Owing to several advantages including minimized dosage and side effect, optimized efficacy, and reversal of multidrug resistance, subcellular organelle-targeted therapies have garnered significant research interest in recent years. In this review, we comprehensively summarize the distribution of drug targets, targeted delivery strategies at various levels, and sophisticated strategies for targeting specific subcellular organelles. Additionally, we highlight the significance of subcellular targeting in cancer therapy and present essential considerations for its clinical translation.

Responsive boronate ester lipid nanoparticles for enhanced delivery of veliparib and platinum (IV) prodrug in chemotherapy

The chemotherapeutic effectiveness of breast cancer treatment is currently unsatisfactory due to inadequate drug delivery, suboptimal drug release, and drug inactivation. Herein, we present an innovative boronate ester lipid nanoformulation to improve the delivery of a platinum (IV) prodrug (Pt-C12) and veliparib (Veli), aiming to increase their therapeutic efficacy through a synergistic effect. We identify the optimal ratio of Pt-C12 to Veli for achieving synergy in vitro, followed by the encapsulation of Pt-C12 and Veli in lipid nanoparticles (NPs) incorporating responsive boronate ester lipids (LPC-PPE) to produce responsive lipid NPs (LPV NPs). These LPV NPs demonstrate high sensitivity to low levels of hydrogen peroxide (H2O2), enabling efficient drug release. In contrast, the nonresponsive lipid NP (DPV NP) control shows minimal responsiveness to H2O2. Furthermore, acidic tumor microenvironments trigger phenylboronic acid (PBA) generation from LPC-PPE in the LPV NPs. Compared with DPV NPs, the interaction between PBA on the LPV NPs and sugar components on tumor cells significantly improves LPV NP cellular uptake and lysosomal escape in vitro. Due to the enhanced cellular delivery and the synergistic drug combination, the LPV NPs induce an increase in apoptosis in 4 T1 cells compared with control groups. Moreover, the LPV NPs exhibit greater efficiency of drug delivery to tumors than the DPV NPs, and have a greater inhibitory effect on tumors than the controls. Overall, our findings highlight the potential of functional lipids and synergistic drug combinations in overcoming obstacles in breast cancer treatment and advancing the development of responsive delivery systems.

Non-nuclear localization signal-guided CRISPR/Cas9 ribonucleoproteins for translocation and gene editing via apoferritin delivery vectors

Direct delivery of the Cas9/sgRNA ribonucleoprotein (RNP) via appropriate carriers has been proved to be an important advance for the in vivo translocation and gene editing of CRISPR/Cas9. These carriers often require the nuclear localization signal (NLS) to fuse with Cas9 or the NLS-bearing protein to form a complex with Cas9 to enter the nucleus. In this study, we introduced apoferritin nanocages as carriers and DOX as a nuclear trigger for the nuclear transport of the Cas9/sgRNA ribonucleoprotein without the NLS (RNP-). Our experiments showed that loading RNP- and DOX into 4L-FTH subunit-based apoferritin nanocages leads to efficient endocytosis and lysosomal escape. Specifically, when DOX was administered at a concentration of 1 μM, we observed the activation of cellular defense mechanisms, which effectively facilitated the translocation of 4L-HFn@RNP-/DOX nanoparticles into the nucleus, thereby enabling intranuclear RNP- delivery. This strategy has been empirically demonstrated to achieve gene editing efficiencies of approximately 33% for the Lcn2 gene in MDA-MB-231 cells and 17.9% for the copepod green fluorescent protein (copGFP) gene in HeLa.copGFP cells in vitro. Moreover, in vivo editing efficacy, as tested in a HeLa.copGFP nude mouse model, was confirmed to be 16%. This delivery system presents a novel therapeutic approach for the nuclear delivery of small molecules or nucleic acid drugs, potentially overcoming the challenges associated with nuclear entry barriers.

Subcellular targeting strategies for protein and peptide delivery

Cytosolic delivery of proteins and peptides provides opportunities for effective disease treatment, as they can specifically modulate intracellular processes. However, most of protein-based therapeutics only have extracellular targets and are cell-membrane impermeable due to relatively large size and hydrophilicity. The use of organelle-targeting strategy offers great potential to overcome extracellular and cell membrane barriers, and enables localization of protein and peptide therapeutics in the organelles. Although progresses have been made in the recent years, organelle-targeted protein and peptide delivery is still challenging and under exploration. We reviewed recent advances in subcellular targeted delivery of proteins/peptides with a focus on targeting mechanisms and strategies, and highlight recent examples of active and passive organelle-specific protein and peptide delivery systems. This emerging platform could open a new avenue to develop more effective protein and peptide therapeutics.

Engineering dynamic covalent bond-based nanosystems for delivery of antimicrobials against bacterial infections

Nanodrug delivery systems (NDDS) continue to be explored as novel strategies enhance therapy outcomes and combat microbial resistance. The need for the formulation of smart drug delivery systems for targeting infection sites calls for the engineering of responsive chemical designs such as dynamic covalent bonds (DCBs). Stimuli response due to DCBs incorporated into nanosystems are emerging as an alternative way to target infection sites, thus enhancing the delivery of antibacterial agents. This leads to the eradication of bacterial infections and the reduction of antimicrobial resistance. Incorporating DCBs on the backbone of the nanoparticles endows the systems with several properties, including self-healing, controlled disassembly, and stimuli responsiveness, which are beneficial in the delivery and release of the antimicrobial at the infection site. This review provides a comprehensive and current overview of conventional DCBs-based nanosystems, stimuli-responsive DCBs-based nanosystems, and targeted DCBs-based nanosystems that have been reported in the literature for antibacterial delivery. The review emphasizes the DCBs used in their design, the nanomaterials constructed, the drug release-triggering stimuli, and the antibacterial efficacy of the reported DCBs-based nanosystems. Additionally, the review underlines future strategies that can be used to improve the potential of DCBs-based nanosystems to treat bacterial infections and overcome antibacterial resistance.

Live-cell imaging of human apurinic/apyrimidinic endonuclease 1 in the nucleus and nucleolus using a chaperone@DNA probe

Human apurinic/apyrimidinic endonuclease 1 (APE1) plays crucial roles in repairing DNA damage and regulating RNA in the nucleus. However, direct visualization of nuclear APE1 in live cells remains challenging. Here, we report a chaperone@DNA probe for live-cell imaging of APE1 in the nucleus and nucleolus in real time. The probe is based on an assembly of phenylboronic acid modified avidin and biotin-labeled DNA containing an abasic site (named PB-ACP), which cleverly protects DNA from being nonspecifically destroyed while enabling targeted delivery of the probe to the nucleus. The PB-ACP construct specifically detects APE1 due to the high binding affinity of APE1 for both avidin and the abasic site in DNA. It is easy to prepare, biocompatible and allowing for long-term observation of APE1 activity. This molecular tool offers a powerful means to investigate the behavior of APE1 in the nuclei of various types of live cells, particularly for the development of improved cancer therapies targeting this protein.

Current status, challenges and prospects of antifouling materials for oncology applications

Targeted therapy has become crucial to modern translational science, offering a remedy to conventional drug delivery challenges. Conventional drug delivery systems encountered challenges related to solubility, prolonged release, and inadequate drug penetration at the target region, such as a tumor. Several formulations, such as liposomes, polymers, and dendrimers, have been successful in advancing to clinical trials with the goal of improving the drug's pharmacokinetics and biodistribution. Various stealth coatings, including hydrophilic polymers such as PEG, chitosan, and polyacrylamides, can form a protective layer over nanoparticles, preventing aggregation, opsonization, and immune system detection. As a result, they are classified under the Generally Recognized as Safe (GRAS) category. Serum, a biological sample, has a complex composition. Non-specific adsorption of chemicals onto an electrode can lead to fouling, impacting the sensitivity and accuracy of focused diagnostics and therapies. Various anti-fouling materials and procedures have been developed to minimize the impact of fouling on specific diagnoses and therapies, leading to significant advancements in recent decades. This study provides a detailed analysis of current methodologies using surface modifications that leverage the antifouling properties of polymers, peptides, proteins, and cell membranes for advanced targeted diagnostics and therapy in cancer treatment. In conclusion, we examine the significant obstacles encountered by present technologies and the possible avenues for future study and development.

Unlocking the potential: phenylboronic acid as a nuclear-targeting boron agent for neutron capture therapy

It has been proposed that boron neutron capture therapy (BNCT) holds promise as a treatment modality for melanoma. However, the effectiveness of boron agents in delivery remains a critical issue to be addressed for BNCT. To this end, phenylboronic acid, which exhibits good water solubility and low cytotoxicity similar to BPA, has been investigated as a potential nuclear-targeting boron agent. The boron concentration of phenylboronic acid was found to be 74.47 ± 12.17 ng/106 B16F10 cells and 45.77 ± 5.64 ng/106 cells in the nuclei. Molecular docking experiments were conducted to investigate the binding of phenylboronic acid to importin proteins involved in nuclear transport. The potential of phenylboronic acid to serve as a desirable nucleus-delivery boron agent for neutron capture therapy in melanoma warrants further exploration.

Targeting the organelle for radiosensitization in cancer radiotherapy

Radiotherapy is a well-established cytotoxic therapy for local solid cancers, utilizing high-energy ionizing radiation to destroy cancer cells. However, this method has several limitations, including low radiation energy deposition, severe damage to surrounding normal cells, and high tumor resistance to radiation. Among various radiotherapy methods, boron neutron capture therapy (BNCT) has emerged as a principal approach to improve the therapeutic ratio of malignancies and reduce lethality to surrounding normal tissue, but it remains deficient in terms of insufficient boron accumulation as well as short retention time, which limits the curative effect. Recently, a series of radiosensitizers that can selectively accumulate in specific organelles of cancer cells have been developed to precisely target radiotherapy, thereby reducing side effects of normal tissue damage, overcoming radioresistance, and improving radiosensitivity. In this review, we mainly focus on the field of nanomedicine-based cancer radiotherapy and discuss the organelle-targeted radiosensitizers, specifically including nucleus, mitochondria, endoplasmic reticulum and lysosomes. Furthermore, the organelle-targeted boron carriers used in BNCT are particularly presented. Through demonstrating recent developments in organelle-targeted radiosensitization, we hope to provide insight into the design of organelle-targeted radiosensitizers for clinical cancer treatment.

Strategies for the Nuclear Delivery of Metal Complexes to Cancer Cells

The nucleus is an essential organelle for the function of cells. It holds most of the genetic material and plays a crucial role in the regulation of cell growth and proliferation. Since many antitumoral therapies target nucleic acids to induce cell death, tumor-specific nuclear drug delivery could potentiate therapeutic effects and prevent potential off-target side effects on healthy tissue. Due to their great structural variety, good biocompatibility, and unique physico-chemical properties, organometallic complexes and other metal-based compounds have sparked great interest as promising anticancer agents. In this review, strategies for specific nuclear delivery of metal complexes are summarized and discussed to highlight crucial parameters to consider for the design of new metal complexes as anticancer drug candidates. Moreover, the existing opportunities and challenges of tumor-specific, nucleus-targeting metal complexes are emphasized to outline some new perspectives and help in the design of new cancer treatments.

Protein Delivery to the Cytosol and Cell Nucleus via Micellar Nanocarrier-Based Nonendocytic Uptake

Although efficient cell nucleus delivery of exogenous materials can greatly improve their biochemical activity, this is strictly restricted by cellular uptake and intracellular trafficking processes. In the current approach, synthetic carriers are designed for cell delivery of exogenous materials via endocytosis, and nucleus delivery can be achieved via endosomal escape. Here, we demonstrate that a nonendocytic cell uptake approach can be adapted for protein delivery to the cell nucleus. We have designed a phenylboronic acid-terminated micellar carrier that can bind with protein in the presence of green tea polyphenol and deliver protein into the cytosol via the nonendocytic approach. Using this approach, four different proteins are delivered to the cytosol within 15 min, and low-molecular weight proteins are delivered to the nucleus. The designed approach can be extended for delivering macromolecular drugs to subcellular targets for a more efficient therapy.

Tumor Abnormality-Oriented Nanomedicine Design

Anticancer nanomedicines have been proven effective in mitigating the side effects of chemotherapeutic drugs. However, challenges remain in augmenting their therapeutic efficacy. Nanomedicines responsive to the pathological abnormalities in the tumor microenvironment (TME) are expected to overcome the biological limitations of conventional nanomedicines, enhance the therapeutic efficacies, and further reduce the side effects. This Review aims to quantitate the various pathological abnormalities in the TME, which may serve as unique endogenous stimuli for the design of stimuli-responsive nanomedicines, and to provide a broad and objective perspective on the current understanding of stimuli-responsive nanomedicines for cancer treatment. We dissect the typical transport process and barriers of cancer drug delivery, highlight the key design principles of stimuli-responsive nanomedicines designed to tackle the series of barriers in the typical drug delivery process, and discuss the "all-into-one" and "one-for-all" strategies for integrating the needed properties for nanomedicines. Ultimately, we provide insight into the challenges and future perspectives toward the clinical translation of stimuli-responsive nanomedicines.

Intracellular delivery of therapeutic proteins. New advancements and future directions

Achieving the full potential of therapeutic proteins to access and target intracellular receptors will have enormous benefits in advancing human health and fighting disease. Existing strategies for intracellular protein delivery, such as chemical modification and nanocarrier-based protein delivery approaches, have shown promise but with limited efficiency and safety concerns. The development of more effective and versatile delivery tools is crucial for the safe and effective use of protein drugs. Nanosystems that can trigger endocytosis and endosomal disruption, or directly deliver proteins into the cytosol, are essential for successful therapeutic effects. This article aims to provide a brief overview of the current methods for intracellular protein delivery to mammalian cells, highlighting current challenges, new developments, and future research opportunities.

The Dawn of a New Era: Targeting the "Undruggables" with Antibody-Based Therapeutics

The high selectivity and affinity of antibodies toward their antigens have made them a highly valuable tool in disease therapy, diagnosis, and basic research. A plethora of chemical and genetic approaches have been devised to make antibodies accessible to more "undruggable" targets and equipped with new functions of illustrating or regulating biological processes more precisely. In this Review, in addition to introducing how naked antibodies and various antibody conjugates (such as antibody-drug conjugates, antibody-oligonucleotide conjugates, antibody-enzyme conjugates, etc.) work in therapeutic applications, special attention has been paid to how chemistry tools have helped to optimize the therapeutic outcome (i.e., with enhanced efficacy and reduced side effects) or facilitate the multifunctionalization of antibodies, with a focus on emerging fields such as targeted protein degradation, real-time live-cell imaging, catalytic labeling or decaging with spatiotemporal control as well as the engagement of antibodies inside cells. With advances in modern chemistry and biotechnology, well-designed antibodies and their derivatives via size miniaturization or multifunctionalization together with efficient delivery systems have emerged, which have gradually improved our understanding of important biological processes and paved the way to pursue novel targets for potential treatments of various diseases.

Advances in nuclei targeted delivery of nanoparticles for the management of cancer

A carrier is inserted into the appropriate organelles (nucleus) in successful medication transport, crucial to achieving very effective illness treatment. Cell-membrane targeting is the major focus of using nuclei to localize delivery. It has been demonstrated that high quantities of anticancer drugs can be injected directly into the nuclei of cancer cells, causing the cancer cells to die and increasing the effectiveness of chemotherapy. There are several effective ways to functionalize Nanoparticles (NPs), including changing their chemical makeup or attaching functional groups to their surface to increase their ability to target organelles. To cause tumor cells to apoptosis, released medicines must engage with molecular targets on particular organelles when their concentration is high enough. Targeted medication delivery studies will increasingly focus on organelle-specific delivery.

A light-activated polymer with excellent serum tolerance for intracellular protein delivery

The design of efficient materials for intracellular protein delivery has attracted great interest in recent years; however, most current materials for this purpose are limited by poor serum stability due to the early release of cargoes triggered by abundant serum proteins. Here, we propose a light-activated crosslinking (LAC) strategy to prepare efficient polymers with excellent serum tolerance for intracellular protein delivery. A cationic dendrimer engineered with photoactivatable O-nitrobenzene moieties co-assembles with cargo proteins via ionic interactions, followed by light activation to yield aldehyde groups on the dendrimer and the formation of imine bonds with cargo proteins. The light-activated complexes show high stability in buffer and serum solutions, but dis-assemble under low pH conditions. As a result, the polymer successfully delivers cargo proteins green fluorescent protein and β-galactosidase into cells with maintained bioactivity even in the presence of 50% serum. The LAC strategy proposed in this study provides a new insight to improve the serum stability of polymers for intracellular protein delivery.

Dibenzocyclooctyne linked lysine-cyclodextrin for efficient intranucleus delivery of proteins

Intranuclear protein delivery shows great prospects in broadening the application scope of protein therapy and revolutionizing medicine, however, effective delivery of native proteins into the nucleus of cells remains a great challenge. Herein, we report the supramolecular nanoparticles based on the self-assembly of dibenzocyclooctyne (DIBO) linked lysine-cyclodextrin (DLC) for efficient intranucleus delivery of proteins. Coordination-driven self-assembly of DLCs in aqueous solution enables efficient encapsulation of proteins just by simple mixing, so as to maintain their biological activity in a reliable way. DLC nanoparticles ensure effective intranuclear protein delivery for therapeutic applications and gene regulation. This rationally designed DIBO containing amino acid-cyclodextrin derivative allows the development of a convenient and universal nanoplatform for intranuclear delivery of native proteins.

Intranuclear Nanoribbons for Selective Killing of Osteosarcoma Cells

Herein, we show intranuclear nanoribbons formed upon dephosphorylation of leucine-rich L- or D-phosphopeptide catalyzed by alkaline phosphatase (ALP) to selectively kill osteosarcoma cells. Being dephosphorylated by ALP, the peptides are first transformed into micelles and then converted into nanoribbons. The peptides/assemblies first aggregate on cell membranes, then enter cells via endocytosis, and finally accumulate in nuclei (mainly in nucleoli). Proteomics analysis suggests that the assemblies interact with histone proteins. The peptides kill osteosarcoma cells rapidly and are nontoxic to normal cells. Moreover, the repeated stimulation of the osteosarcoma cells by the peptides sensitizes the cancer cells rather than inducing resistance. This work not only illustrates a novel mechanism for nucleus targeting, but may also pave a new way for selectively killing osteosarcoma cells and minimizing drug resistance.

High affinity protein surface binding through co-engineering of nanoparticles and proteins

Control over supramolecular recognition between proteins and nanoparticles (NPs) is of fundamental importance in therapeutic applications and sensor development. Most NP-protein binding approaches use 'tags' such as biotin or His-tags to provide high affinity; protein surface recognition provides a versatile alternative strategy. Generating high affinity NP-protein interactions is challenging however, due to dielectric screening at physiological ionic strengths. We report here the co-engineering of nanoparticles and protein to provide high affinity binding. In this strategy, 'supercharged' proteins provide enhanced interfacial electrostatic interactions with complementarily charged nanoparticles, generating high affinity complexes. Significantly, the co-engineered protein-nanoparticle assemblies feature high binding affinity even at physiologically relevant ionic strength conditions. Computational studies identify both hydrophobic and electrostatic interactions as drivers for these high affinity NP-protein complexes.

Conformational Transition-Triggered Disassembly of Therapeutic Peptide Nanomedicine for Tumor Therapy

Cationic therapeutic peptides have received widespread attention due to their excellent antibacterial and antitumor properties. However, most of these peptides have undesirable delivery efficiency and high hemolytic toxicity due to the positively charged α-helix structure containing many lysine and arginine, which may restrict its in vivo applications. Herein, a conformationally transformed therapeutic peptide Pep-HCO₃ modified with bicarbonates on guanidine groups is designed. Such a design allows Pep-HCO₃ ((nap-RAGLQFPVGRLLRRLLRRLLR) nHCO₃ ) to self-assemble into nanoparticles (NP-Pep) due to disrupting helix folding and the formation of intermolecular hydrogen bonding between bicarbonates and guanidine groups. When pH is from 7.4 to 6.5 at the tumor sites, guanidine bicarbonate can be hydrolyzed to form CO₂ and guanidine groups, resulting in the disassembling of the NP-Pep into monomers α-Pep with a positively charged α-helix structure. In vivo, NP-Pep not only inhibits the tumor growth of xenografted mice with a twofold enhanced inhibition rate compared with α-Pep treatment group, but also significantly reduces the hemolytic toxicity by responding to the pH of tumor microenvironment. Therefore, the strategy of conformational transition-triggered disassembly of nanoparticles allows efficient delivery of cationic therapeutic peptides and lowering the hemolytic toxicity, which may provide an avenue for developing high-performance cationic peptide in vivo applications.

Protein Delivery: If Your GFP (or Other Small Protein) Is in the Cytosol, It Will Also Be in the Nucleus

Intracellular protein delivery is a transformative tool for biologics research and medicine. Delivery into the cytosol allows proteins to diffuse throughout the cell and access subcellular organelles. Inefficient delivery caused by endosomal entrapment is often misidentified as cytosolic delivery. This inaccuracy muddles what should be a key checkpoint in assessing delivery efficiency. Green fluorescent protein (GFP) is a robust cargo small enough to passively diffuse from the cytosol into the nucleus. Fluorescence of GFP in the nucleus is a direct readout for cytosolic access and effective delivery. Here, we highlight recent examples from the literature for the accurate assessment of cytosolic protein delivery using GFP fluorescence in the cytosol and nucleus.

Nuclear delivery of dual anti-cancer drugs by molecular self-assembly

Nanomedicines generally suffer from poor accumulation in tumor cells, low anti-tumor efficacy, and drug resistance. In order to address these problems, we introduced a novel nanomedicine based on dual anti-cancer drugs, which showed good cell nuclear accumulation properties. The novel nanomedicine consisted of three components: (1) dual anti-cancer drugs, 10-hydroxycamptothecin (HCPT) and chlorambucil (CRB), whose targets are located in the cell nucleus, (2) a nuclear localizing dodecapeptide, PMI peptide (TSFAEYWNLLSP), which could activate p53 by binding with MDM2 and MDMX located in the cell nucleus, and (3) an efficient self-assembling tripeptide FFY. Our nanomedicine exhibited enhanced cellular uptake and nuclear accumulation properties, thus achieving an excellent anti-cancer capacity both in vitro and in vivo. Our study will provide an inspiration for the development of novel multifunctional nanomaterials for cancer diagnosis and therapy.

Dynamic Continuum of Nanoscale Peptide Assemblies Facilitates Endocytosis and Endosomal Escape

Alkaline phosphatase (ALP) enables intracellular targeting by peptide assemblies, but how the ALP substrates enter cells remains elusive. Here we show that nanoscale phosphopeptide assemblies cluster ALP to enable caveolae-mediated endocytosis (CME) and endosomal escape. Specifically, fluorescent phosphopeptides undergo enzyme-catalyzed self-assembly to form nanofibers. Live cell imaging unveils that phosphopeptides nanoparticles, coincubated with HEK293 cells overexpressing red fluorescent protein-tagged tissue-nonspecific ALP (TNAP-RFP), cluster TNAP-RFP in lipid rafts to enable CME. Further dephosphorylation of the phosphopeptides produces peptidic nanofibers for endosomal escape. Inhibiting TNAP, cleaving the membrane anchored TNAP, or disrupting lipid rafts abolishes the endocytosis. Decreasing the transformation to nanofibers prevents the endosomal escape. As the first study establishing a dynamic continuum of nanoscale assemblies for cellular uptake, this work illustrates an effective design for enzyme-responsive supramolecular therapeutics and provides mechanism insights for understanding the dynamics of cellular uptake of proteins or exogenous peptide aggregates.

Cancer cell membrane-coated gold nanorods for photothermal therapy and radiotherapy on oral squamous cancer

The combination of different modalities greatly enhances the anticancer efficacy of each treatment by combining their merits, showing promising potential in clinical translation. Herein, we fabricated cancer cell membrane-coated gold nanorods (GNR@Mem) possessing excellent photothermal transfer ability in the second near-infrared window and radiosensitizing ability under X-ray irradiation. The cancer cell membrane coating endowed the nanomedicine with stability in the physiological environment and selective homotypic targeting to specific cancer cells in vitro. Under NIR light and X-ray irradiation, the gold nanorods induced a temperature increase, reactive oxygen generation, and subsequent damage to the DNA helix structure, leading to enhanced cell apoptosis. Benefitting from its relative long circulation time in the blood and homotypic targeting effect, the tumor accumulation of GNR@Mem significantly increased. The in vivo results demonstrate that the combination of photothermal therapy and radiotherapy effectively suppresses tumor growth without noticeable systemic toxicity.

Cellular- and Subcellular-Targeted Delivery Using a Simple All-in-One Polymeric Nanoassembly

Nanocarrier-mediated drug delivery is a promising strategy to maximize the power of chemotherapy and minimize side effects. However, current approaches show insufficient drug-loading capacity and inefficient drug release, and require complex modification processes. Attempts to enhance one of these features often compromise other merits. We describe here a block copolymer assembly system that combines desirable characteristics. The design of self-immolative and crosslinkable hydrophobic moieties offer stable and high encapsulation. Redox-triggerable polymer self-immolation promotes drug release by switching the hydrophobic core into completely hydrophilic chains. The reactive amine handles, presented on their surface, allow "plug to direct" modification with targeting ligands. Functionalized nanoassemblies have been programmed to target specific subcellular compartments. The simplicity, versatility, and efficacy of the system open up possibilities for an all-in-one delivery system.

Azide-Terminated RAFT Polymers for Biological Applications

Reversible addition-fragmentation chain-transfer (RAFT) polymerization is a commonly used polymerization methodology to generate synthetic polymers. The products of RAFT polymerization, i.e., RAFT polymers, have been widely employed in several biologically relevant areas, including drug delivery, biomedical imaging, and tissue engineering. In this article, we summarize a synthetic methodology to display an azide group at the chain end of a RAFT polymer, thus presenting a reactive site on the polymer terminus. This platform enables a click reaction between azide-terminated polymers and alkyne-containing molecules, providing a broadly applicable scaffold for chemical and bioconjugation reactions on RAFT polymers. We also highlight applications of these azide-terminated RAFT polymers in fluorophore labeling and for promoting organelle targeting capability. © 2020 Wiley Periodicals LLC. Basic Protocol 1: Synthesis of the azide derivatives of chain transfer agent and radical initiator Basic Protocol 2: Installation of an azide group on the α-end of RAFT polymers Alternate Protocol: Installation of an azide group on the ω-end of RAFT polymers Basic Protocol 3: Click reaction between azide-terminated RAFT polymers and alkyne derivatives.

Advanced engineered nanoparticulate platforms to address key biological barriers for delivering chemotherapeutic agents to target sites

The widespread development of nanocarriers to deliver chemotherapeutics to specific tumor sites has been motivated by the lack of selective targeting during chemotherapy inducing serious side effects and low therapeutic efficacy. The utmost challenge in targeted cancer therapies is the ineffective drug delivery system, in which the drug-loaded nanocarriers are hindered by multiple complex biological barriers that compromise the therapeutic efficacy. Despite considerable progress engineering novel nanoplatforms for the delivery of chemotherapeutics, there has been limited success in a clinical setting. In this review, we identify and analyze design strategies for improved therapeutic efficacy and unique properties of nanoplatforms, including liposomes, polymeric micelles, nanogels, and dendrimers. We provide a comprehensive and integral description of key biological barriers that nanoplatforms are exposed to during their in vivo journey and discuss associated strategies to overcome these barriers based on the latest research and information available in the field. We expect this review to provide constructive information for the rational design of more effective nanoplatforms to advance precision therapies and accelerate their clinical translation.

Targeted Engineering of Medicinal Chemistry for Cancer Therapy: Recent Advances and Perspectives

Severe side effects and poor therapeutic efficacy are the main drawbacks of current anticancer drugs. These problems can be mitigated by targeting, but the targeting efficacy of current drugs is poor and urgently needs improvement. Taking this into consideration, this Review first summarizes the current targeting strategies for cancer therapy in terms of cancer tissue and organelles. Then, we analyse the systematic targeting of anticancer drugs and conclude that a typical journey for a targeted drug administered by intravenous injection is a CTIO cascade of at least four steps. Furthermore, to ensure high overall targeting efficacy, the properties of a targeting drug needed in each step are further analysed, and some guidelines for structure optimization to obtain effective targeting drugs are offered. Finally, some viewpoints highlighting the crucial problems and potential challenges of future research on targeted cancer therapy are presented. This review could actively promote the development of precision medicine against cancer.

Accessing Intracellular Targets through Nanocarrier-Mediated Cytosolic Protein Delivery

Protein-based therapeutics have unique therapeutic potential due to their specificity, potency, and low toxicity. The vast majority of intracellular applications of proteins require access to the cytosol. Direct entry to the cytosol is challenging due to the impermeability of the cell membrane to proteins. As a result, multiple strategies have focused on endocytic uptake of proteins. Endosomally entrapped cargo, however, can have very low escape efficiency, with protein degradation occurring in acidic endolysosomal compartments. In this review, we briefly discuss endosomal escape strategies and review the strategy of cell membrane fusion, a recent strategy for direct delivery of proteins into the cell cytoplasm.

Tumor microenvironment-responsive multifunctional peptide coated ultrasmall gold nanoparticles and their application in cancer radiotherapy

Two important features are required for promising radiosensitizers: one is selective tumor cell targeting to enhance the therapeutic outcome via lethal DNA damage and the other is rapid clearance to enable excellent biocompatibility for potential clinical application. Herein, ultrasmall gold nanoparticles (Au NPs) with diameter smaller than 5 nm were prepared and covered with a multifunctional peptide to endow them with selective tumor cell uptake capability. Combined with X-ray irradiation, the responsive Au NPs demonstrated superior radio-sensitizing toxicity and rapid renal clearance in vivo. Methods: A responsive peptide (Tat-R-EK) consists of three build blocks were used: a cell and even nuclear penetrating block derived from human immunodeficiency virus-1 transactivator of transcription protein (Tat), an cathepsin B cleavable linker, and a zwitterionic antifouling block. Ultrasmall Au NPs were prepared and then covered by the peptide via the Au-S bonds between gold and thiol groups from cysteine. The morphology, colloidal stability and the responsiveness of obtained Au@Tat-R-EK NPs were studied using transmittance electron microscopy and dynamic laser scattering. The selective cancer cell uptake and accumulation of Au@Tat-R-EK NPs in cancer tissue were studied via ICP-MS in vitro and in vivo, respectively. The cytotoxicity of Au@Tat-R-EK NPs on HepG2 cancer cells was evaluated in terms of cell viability, DNA damage, intracellular reactive oxygen species generation, and apoptosis analysis. Finally, the biocompatibility and tumor destruction ability against orthotopic LM3 liver cancers were verified in vivo. Results: Multifunctional peptide modified ultrasmall Au NPs were successfully prepared. The Au NPs exhibited enough colloidal stability and cathepsin B-responsive surface change, leading to selectively uptake by cancer cells in vitro and accumulation to tumor sites in vivo. Combined with X-ray irradiation, the responsive Au NPs demonstrated superior radio-sensitizing cytotoxicity in vitro and therapeutic outcome on mouse liver cancer in vivo. The ultrasmall size enables rapid clearance of the Au NPs, guarantees the biocompatibility in vivo for potential clinical applications. Conclusion: Some obstacles faced by the Au NPs-based radiotherapy, such as short circulation half-life, non-specific distribution, slow clearance and low radio-sensitizing effect, were effective solved through rational design of the smart nanomedicine. This work provides new insight in designing tumor microenvironment-responsive nanomedicine in cancer radiotherapy.

Cytosolic Delivery of Functional Proteins In Vitro through Tunable Gigahertz Acoustics

Intracellular delivery is essential to therapeutic applications such as genome engineering and disease diagnosis. Current methods lack simple, noninvasive strategies and are often hindered by long incubation time or high toxicity. Hydrodynamic approaches offer rapid and controllable delivery of small molecules, but thus far have not been demonstrated for delivering functional proteins. In this work, we developed a robust hydrodynamic approach based on gigahertz (GHz) acoustics to achieve rapid and noninvasive cytosolic delivery of biologically active proteins. With this method, GHz-based acoustic devices trigger oscillations through a liquid medium (acoustic streaming), generating shear stress on the cell membrane and inducing transient nanoporation. This mechanical effect enhances membrane permeability and enables cytosolic access to cationic proteins without disturbing their bioactivity. We evaluated the versatility of this approach through the delivery of cationic fluorescent proteins to a range of cell lines, all of which displayed equally efficient delivery speed (≤20 min). Delivery of multiple enzymatically active proteins with functionality related to apoptosis or genetic recombination further demonstrated the relevance of this method.

Enhanced nuclear delivery of H1-S6A, F8A peptide by NrTP6-modified polymeric platform

Nucleus is the central regulator of cell metabolism, growth and differentiation, which is considered as an effective target for the treatment of many diseases. To efficiently deliver drugs into nucleus, delivery systems have to bypass a number of barriers especially crossing the cell membrane and nuclear envelope. Here we report a nucleolar targeting peptide (NrTP6) modified polymeric conjugate platform based on N-(2-hydroxypropyl)-methacrylamide (HPMA) copolymers for enhanced nuclear delivery of H1-S6A, F8A peptide to hinder c-Myc from binding to DNA. On one hand, the modification of NrTP6 would promote cellular uptake and nuclear accumulation of the conjugates, and on the other hand, the conjugates can release smaller molecular weight subunits (H1-NrTP6) via cleavage of lysosomally enzyme-sensitive spacer for facilitating nucleus transport. It was found that NrTP6 modified HPMA copolymer-H1 peptide conjugates could improve internalization and nuclear accumulation of H1 peptide by 2.2 and 37.1-fold, respectively, compared to the non-NrTP6 modified ones, in HeLa cells. Moreover, the same trend was found in MDA-MB-231 cells and 4T1 cells. In addition, we found that the nuclear targeting mechanism of NrTP6 peptide mediation may be associated with the importin α/β pathway. Furthermore, the in vivo investigation revealed that NrTP6-modified polymeric platform exhibited the best therapeutic efficacy with a tumor growth inhibition rate of 77.0%. These results indicated that NrTP6 modification was a promising strategy for simultaneously realizing cellular internalization and nuclear targeting, which might provide a new path for intranuclear drug delivery.

Boronic acid-engineered gold nanoparticles for cytosolic protein delivery

Boronic acid-engineered gold nanoparticles for effective cytosolic protein delivery with the help of hypertonicity.

Enhanced cellular uptake and nuclear accumulation of drug-peptide nanomedicines prepared by enzyme-instructed self-assembly

Subcellular delivery of nanomedicines has emerged as a promising approach to enhance the therapeutic efficacy of anticancer drugs. Nuclear accumulation of anticancer drugs are essential for its therapeutic efficacy because their targets are generally located within the nucleus. However, strategies for the nuclear accumulation of nanomedicines with anticancer drugs rarely reported. In this study, we reported a promising nanomedicine, comprising a drug-peptide amphiphile, with enhanced cellular uptake and nuclear accumulation capability for cancer therapy. The drug-peptide amphiphile consisted of the peptide ligand PMI (TSFAEYWNLLSP), which was capable of activating the p53 gene by binding with the MDM2 and MDMX located in the cell nucleus. Peptide conformations could be finely tuned by using different strategies including heating-cooling and enzyme-instructed self-assembly (EISA) to trigger molecular self-assembly at different temperatures. Due to the different peptide conformations, the drug-peptide amphiphile self-assembled into nanomedicines with various properties, including stabilities, cellular uptake, and nuclear accumulation. The optimized nanomedicine formed by EISA strategy at a low temperature of 4 °C showed enhanced cellular uptake and nuclear accumulation capability, and thus exhibited superior anticancer ability both in vitro and in vivo. Overall, our study provides a useful strategy for finely tuning the properties and activities of peptide-based supramolecular nanomaterials, which may lead to optimized nanomedicines with enhanced performance.

Assemblies of d-Peptides for Targeting Cell Nucleolus

Selectively targeting the cell nucleolus remains a challenge. Here, we report the first case in which d-peptides form membraneless molecular condensates with RNA for targeting cell nucleolus. A d-peptide derivative, enriched with lysine and hydrophobic residues, self-assembles to form nanoparticles, which enter cells through clathrin-dependent endocytosis and mainly accumulate at the cell nucleolus. A structural analogue of the d-peptide reveals that the particle morphology of the assemblies, which depends on the side chain modification, favors the cellular uptake. In contrast to those of the d-peptide, the assemblies of the corresponding l-enantiomer largely localize in cell lysosomes. Preliminary mechanism study suggests that the d-peptide nanoparticles interact with RNA to form membraneless condensates in the nucleolus, which further induces DNA damage and results in cell death. This work illustrates a new strategy for rationally designing supramolecular assemblies of d-peptides for targeting subcellular organelles.

Curved corannulene dually targets mitochondria and endoplasmic reticulum, and initiates apoptosis via localized ROS induction upon light triggering

Organelle-targeting agents are promising in both fundamental and applied biomedicine research, but such materials are very limited. As a curved 2D carbon material, corannulene (Cor) displays an uneven intramolecular electron distribution, producing a large dipole moment that can favor the electrostatic interaction. Based on the large negative mitochondrial membrane potential and the presence of a connection structure between mitochondria and endoplasmic reticulum (ER), we hypothesized that Cor could simultaneously target both mitochondria and ER. Such hypothesis was well validated by using the fluorescence tag-labelled Cor. The co-localization analysis in a model cell line (PC3) revealed a preferred accumulation of Cor in both organelles, as evidenced by a large Pearson correlation coefficient. The large dipole also empowered Cor the ability of controlled production of reactive oxygen species (ROS) upon light irradiation. This feature plus mitochondria targeting of Cor induced depletion of adenosine triphosphate (ATP) and caspase 9/3 activation. The triggered ROS generation in ER caused the calcium dumping in the cytosol, as revealed by a calcium-specific fluorescence probe. A significant degree of apoptosis was induced by Cor as a result of the interplay of dual mitochondria/ER targeting and triggered organelle-specific ROS delivery. This study demonstrated the subcellular targeting ability of Cor for potential ROS-based therapy, and implied that the dipole could be a valuable parameter for efficient design and tailored screening of organelle-targeting materials for various biomedical applications.

In situ real-time tracing of hierarchical targeting nanostructures in drug resistant tumors using diffuse fluorescence tomography

Nanoparticles that respond to specific endogenous or exogenous stimuli in tumor tissues are actively being developed to address multidrug resistance owing to multiple advantages, including a prolonged circulation time, enhanced permeability and retention effect, and superior cellular uptake. Although some exciting results have been obtained, existing nanoparticles have limited routes to overcome the drug resistance of tumor cells; this limitation results in a failure to ablate resistant tumors via intravenous administration. To resolve this dilemma, we developed a smart theranostic nanoplatform with programmable particle size, activatable target ligands and in vivo multimodal imaging. This nanoplatform, which includes stealth zwitterionic coating, was shown to be quickly trapped in tumor tissue from the blood circulation within 5 min. Subsequently, the targeting moieties were activated in response to the acidic tumor microenvironment by triggering the zwitterionic shell detachment, driving the peeled nanoparticles to penetrate into tumor cells. These smart nanoparticles completely inhibited drug-resistant tumor growth and did not cause any damage to normal organ tissues in live animals. The designed nanoplatforms simultaneously acted as a nanoprobe for fluorescence imaging. Moreover, we also used noninvasive pharmacokinetic diffuse fluorescence tomography (DFT) to dynamically monitor and in situ real-time trace the nanoplatforms' behavior throughout the entire tumor in live animals. The nanoplatforms enabled rapid drug accumulation and deep penetration throughout the entire tumor. The rate of drug accumulation after the administration of nanoplatforms was five-fold higher compared with that after the administration of the free drug, which resulted in increased drug delivery efficiency and improved antitumor efficacy. Collectively, this hierarchical vehicle design provides promising insights for the development of theragnosis for multidrug resistant tumors.

Specific Delivery of Oligonucleotides to the Cell Nucleus via Gentle Compression and Attachment of Polythymidine

Nonviral delivery of nucleic acids to the cell nucleus typically requires chemical methods that do not guarantee specific delivery (e.g., transfection agent) or physical methods that may require extensive fabrication (e.g., microfluidics) or an elevated pressure (e.g., 10⁵ Pa for microneedles). We report a method of delivering oligonucleotides to the nucleus with high specificity (relative to the cytosol) by synergistically combining chemical and physical approaches. Particularly, we demonstrate that DNA oligonucleotides appended with a polythymidine [poly(T)] segment (chemical) profusely accumulate inside the nucleus when the cells are under gentle compression imposed by the weight of a single glass coverslip (physical; ∼2.2 Pa). Our "compression-cum-poly(T)" delivery method is simple, can be generalizable to three "hard-to-transfect" cell types, and does not induce significant levels of cytotoxicity or long-term oxidative stress to the treated cells when provided the use of suitable compression times and oligonucleotide concentrations. In bEnd.3 endothelial cells, compression-aided intranuclear delivery of poly(T) is primarily mediated by importin β and nucleoporin 62. Our method significantly enhances the intranuclear delivery of antisense oligonucleotides to bEnd.3 endothelioma cells and the inhibition of two target genes, including a reporter gene encoding the enhanced green fluorescent protein and an intranuclear lncRNA oncogene (metastasis-associated lung adenocarcinoma transcript 1), when compared with delivery without gentle compression or poly(T) attachment. Our data underscore the critical roles of pressure and nucleotide sequence on the intranuclear delivery of nucleic acids.

Lost or Forgotten: The nuclear cathepsin protein isoforms in cancer

While research into the role of cathepsins has been progressing at an exponential pace over the years, research into their respective isoform proteins has been less frenetic. In view of the functional and biological potential of such protein isoforms in model systems for cancer during their initial discovery, much later they have offered a new direction in the field of cathepsin basic and applied research. Consequently, the analysis of such isoforms has laid strong foundations in revealing other important regulatory aspects of the cathepsin proteins in general. In this review article, we address these key aspects of cathepsin isoform proteins, with particular emphasis on how they have shaped what is now known in the context of nuclear cathepsin localization and what potential these hold as nuclear-based therapeutic targets in cancer.