Small-Molecule Prodrug Nanoassemblies: An Emerging Nanoplatform for Anticancer Drug Delivery

Self-assembled hyaluronic acid nanomicelle for enhanced cascade cancer chemotherapy via self-sensitized ferroptosis

The clinical utility of chemotherapy is often compromised by its limited efficacy and significant side effects. Addressing these concerns, we have developed a self-assembled nanomicelle, namely SANTA FE OXA, which consists of hyaluronic acid (HA) conjugated with ferrocene methanol (FC), oxaliplatin prodrug (OXA(IV)) and ethylene glycol-coupled linoleic acid (EG-LA). Targeted delivery is achieved by HA binding to the CD44 receptors that are overexpressed on tumor cells, facilitating drug uptake. Once internalized, hyaluronidase (HAase) catalyzes the digestion of the SANTA FE OXA, releasing FC and reducing OXA(IV) into an active form. The active oxaliplatin (OXA) induces DNA damage and increases intracellular hydrogen peroxide (H2O2) levels via cascade reactions. Simultaneously, FC disrupts the redox balance within tumor cells, inducing ferroptosis. Both in vivo and in vitro experiments confirmed that SANTA FE OXA inhibited tumor growth by combining cascade chemotherapy and self-sensitized ferroptosis, achieving a tumor inhibition rate of up to 76.61 %. Moreover, this SANTA FE OXA significantly mitigates the systemic toxicity commonly associated with platinum-based chemotherapeutics. Our findings represent a compelling advancement in nanomedicine for enhanced cascade cancer therapy.

Cholesterol sulfate-mediated ion-pairing facilitates the self-nanoassembly of hydrophilic cationic mitoxantrone

HYPOTHESIS

Hydrophilic cationic drugs such as mitoxantrone hydrochloride (MTO) pose a significant delivery challenge to the development of nanodrug systems. Herein, we report the use of a hydrophobic ion-pairing strategy to enhance the nano-assembly of MTO.

EXPERIMENTS

We employed biocompatible sodium cholesteryl sulfate (SCS) as a modification module to form stable ion pairs with MTO, which balanced the intermolecular forces and facilitated nano-assembly. PEGylated MTO-SCS nanoassemblies (pMS NAs) were prepared via nanoprecipitation. We systematically evaluated the effect of the ratio of the drug module (MTO) to the modification module (SCS) on the nanoassemblies.

FINDINGS

The increased lipophilicity of MTO-SCS ion pair could significantly improve the encapsulation efficiency (∼97 %) and cellular uptake efficiency of MTO. The pMS NAs showed prolonged blood circulation, maintained the same level of tumor antiproliferative activity, and exhibited reduced toxicity compared with the free MTO solution. It is noteworthy that the stability, cellular uptake, cytotoxicity, and in vivo pharmacokinetic behavior of the pMS NAs increased in proportion to the molar ratio of SCS to MTO. This study presents a self-assembly strategy mediated by ion pairing to overcome the challenges commonly associated with the poor assembly ability of hydrophilic cationic drugs.

Quantitatively analyzing the dissociation and release of disulfide-containing organic nanoparticles

The disintegration of nanoparticles and drug release are important and imperative for nanoparticle formulations of therapeutic agents. However, quantitatively monitoring the drug release of nanomedicines is a major challenge. In this work, boron-dipyrromethene (BDP) was applied as a model drug to study the disassembly of nanoparticles and drug release. BDP dimers with disulfide and ester bonds were synthesized, and their nanoparticles were made. The accurate analysis of bond breaking in BDP nanoparticles could not be realized by using confocal laser scanning microscopy. Hence, the possible products after bond cleavage were quantified by using liquid chromatography tandem mass spectrometry (LC-MS/MS). BDP nanoparticles could be endocytosed into cancer cells, and the disulfide bonds and ester bonds were broken to promote the disassociation of nanoparticles and BDP release. Then, near-infrared BDP nanoparticles were investigated in live mice by near-infrared fluorescence imaging and LC-MS/MS. The release of BDP was low (<10%) and BDP maintained the original dimer structure in vivo, which showed that the bond breaking for BDP nanoparticles was difficult in vivo. These results could help us understand the breaking law of disulfide bonds and ester bonds in nanoparticles and are beneficial for developing practical new drug formulations.

Redox-sensitive disulfide-bridged self-assembled nanoparticles of dexamethasone with high drug loading for acute lung injury therapy

Acute lung injury (ALI) arises from an excessive inflammatory response, usually progressing to acute respiratory distress syndrome (ARDS) if not promptly addressed. There is currently a limited array of effective treatments available for ALI. In this study, we developed disulfide bond-bridged prodrug self-assembled nanoparticles (referred to as DSSS NPs). These nanoparticles were consisted of Dexamethasone (Dex) and stearic acid (SA), and were designed to target and treat ALI. DSSS NPs demonstrated a substantial drug loading capacity with 37.75 % of Dex, which is much higher than conventional nanomedicines (usually < 10 %). Moreover, they exhibited the potential to specifically target injured lung tissue and inflammatory microenvironment-responsive release drugs. Consequently, DSSS NPs reduced significantly the levels of pro-inflammatory cytokines and tissue damage in mice with ALI induced by lipopolysaccharide (LPS). Overall, DSSS NPs offer a promising strategy for treatment of acute lung injury.

Enhancing ovarian cancer treatment with maleimide-modified Pt(IV) prodrug nanoparticles

The limitations of platinum in ovarian cancer therapy, such as poor solubility and significant side effects, often lead to suboptimal therapeutic outcome and mortality. In this study, we have developed a novel approach utilizing biodegradable polymeric nanoparticles as a drug delivery system (NDDS), loaded with advanced platinum (IV) (Pt(IV)) prodrugs. A key feature of our approach is the enhancement of nanoparticles with maleimide, a modification hypothesized to significantly boost tumor tissue accumulation. When tested in mouse models of orthotopic and peritoneal metastasis ovarian cancer, these maleimide-modified nanoparticles are anticipated to show preferential accumulation in tumor tissues, enhancing therapeutic efficiency and minimizing systemic drug exposure. Our findings demonstrate that the maleimide-modified Pt(IV)-loaded NDDSs significantly reduce tumor burden in comparison to traditional cisplatin therapy, while simultaneously reducing adverse side effects. This leads to markedly improved survival rates in models of peritoneal metastasis ovarian cancer, offering a promising new direction in the treatment of this challenging disease.

Liver-Targeted Delivery Based on Prodrug: Passive and Active Approaches

BACKGROUND

The liver, a central organ in human metabolism, is often the primary target for drugs. However, conditions such as viral hepatitis, cirrhosis, non-alcoholic fatty liver disease (NAFLD), and hepatocellular carcinoma (HCC) present substantial health challenges worldwide. Existing treatments, which suffer from the non-specific distribution of drugs, frequently fail to achieve desired efficacy and safety, risking unnecessary liver harm and systemic side effects.

PURPOSE

The aim of this review is to synthesize the latest progress in the design of liver-targeted prodrugs, with a focus on passive and active targeting strategies, providing new insights into the development of liver-targeted therapeutic approaches.

METHODS

This study conducted an extensive literature search through databases like Google Scholar, PubMed, Web of Science, and China National Knowledge Infrastructure (CNKI), systematically collecting and selecting recent research on liver-targeted prodrugs. The focus was on targeting mechanisms, including the Enhanced Permeability and Retention (EPR) effect, the unique microenvironment of liver cancer, and active targeting through specific transporters and receptors.

RESULTS

Active targeting strategies achieve precise drug delivery by binding specific ligands to liver surface receptors. Passive targeting takes advantage of the EPR effect and tumor characteristics to enrich drugs in liver tumors. The review details successful cases of using small molecule ligands, peptides, antibodies and nanoparticles as drug carriers.

CONCLUSION

Liver-targeted prodrug strategies show great potential in enhancing the efficacy of drug treatment and reducing side effects for liver diseases. Future research should balance the advantages and limitations of both targeting strategies, focusing on optimizing drug design and targeting efficiency, especially for clinical application. In-depth research on liver-specific receptors and the development of innovative targeting molecules are crucial for advancing the field of liver-targeted prodrugs.

Modular Prodrug-Engineered Oxygen Nano-Tank With Outstanding Nanoassembly Performance, High Oxygen Loading, and Closed-Loop Tumor Hypoxia Relief

The clinical translation of tumor hypoxia intervention modalities still falls short of expectation, restricted by poor biocompatibility of oxygen-carrying materials, unsatisfactory oxygen loading performance, and abnormally high cellular oxygen consumption-caused insufficient hypoxia relief. Herein, a carrier-free oxygen nano-tank based on modular fluorination prodrug design and co-assembly nanotechnology is elaborately exploited, which is facilely fabricated through the molecular nanoassembly of a fluorinated prodrug (FSSP) of pyropheophorbide a (PPa) and an oxygen consumption inhibitor (atovaquone, ATO). The nano-tank adeptly achieves sufficient oxygen enrichment while simultaneously suppressing oxygen consumption within tumors for complete tumor hypoxia alleviation. Significant, the fluorination module in FSSP not only confers favorable co-assemblage of FSSP and ATO, but also empowers the nanoassembly to readily carry oxygen. As expected, it displays excellent oxygen carrying capacity, favorable pharmacokinetics, on-demand laser-triggerable ATO release, closed-loop tumor hypoxia relief, and significant enhancement to PPa-mediated PDT in vitro and in vivo. This study provides a novel nanotherapeutic paradigm for tumor hypoxia intervention-enhanced cancer therapy.

Precisely Self-Cooperative Nanoassembly Enables Photothermal/Ferroptosis Synergistic Tumor Eradication

Ferroptosis is identified as a potential target for anticancer therapy. However, most conventional ferroptosis inducers not only fail to trigger intracellular lipid peroxidation storm, but are also prone to cause ferroptosis-related toxicity through off-target destruction of intracellular antioxidant defense systems. Therefore, a potent and highly tumor-specific ferroptosis induction modality is desired. Herein, a self-cooperative nanomedicine for imaging-guided photothermal ferrotherapy, which is fabricated based on molecular nanoassembly (NA) of DiR (a photothermal probe) and ferrocene (Fc, a reactant of the Fenton reaction), is elaborately exploited. DiR-elicited hyperthermia induces both photothermal therapy (PTT) and a significant acceleration of the kinetics of the Fc-involved Fenton reaction, collaboratively causing a lipid peroxidation storm in tumor cells. In turn, plenty of lipid peroxides boost PTT through the downregulation of heat shock protein 90. As expected, such a self-cooperative NA demonstrates synergetic tumor eradication in the 4T1 breast tumor-bearing mice xenograft model. This study offers a novel nanotherapeutic paradigm for precise multimodal cancer therapy.

pH-responsive self-assembled nanoparticles for tumor-targeted drug delivery

Recent advances in the field of drug delivery have opened new avenues for the development of novel nanodrug delivery systems (NDDS) in cancer therapy. Self-assembled nanoparticles (SANPs) based on tumour microenvironment have great advantages in improving antitumor effect, and pH-responsive SANPs prepared by the combination of pH-responsive nanomaterials and self-assembly technology can effectively improve the efficacy and reduce the systemic toxicity of antitumor drugs. In this review, we describe the characteristics of self-assembly and its driving force, the mechanism of pH-responsive NDDS, and the nanomaterials for pH-responsive SANPs type. A series of pH-responsive SANPs for tumour-targeted drug delivery are discussed, with an emphasis on the relation between structural features and theranostic performance.

Light-Triggered PROTAC Nanoassemblies for Photodynamic IDO Proteolysis in Cancer Immunotherapy

While proteolysis-targeting chimeras (PROTACs) hold great potential for persistently reprogramming the immunosuppressive tumor microenvironment via targeted protein degradation, precisely activating them in tumor tissues and preventing uncontrolled proteolysis at off-target sites remain challenging. Herein, a light-triggered PROTAC nanoassembly (LPN) for photodynamic indoleamine 2,3-dioxygenase (IDO) proteolysis is reported. The LPN is derived from the self-assembly of prodrug conjugates, which comprise a PROTAC, cathepsin B-specific cleavable peptide linker, and photosensitizer, without any additional carrier materials. In colon tumor models, intravenously injected LPNs initially silence the activity of PROTACs and accumulate significantly in targeted tumor tissues due to an enhanced permeability and retention effect. Subsequently, the cancer biomarker cathepsin B begins to trigger the release of active PROTACs from the LPNs through enzymatic cleavage of the linkers. Upon light irradiation, tumor cells undergo immunogenic cell death induced by photodynamic therapy to promote the activation of effector T cells, while the continuous IDO degradation of PROTAC simultaneously blocks tryptophan metabolite-regulated regulatory-T-cell-mediated immunosuppression. Such LPN-mediated combinatorial photodynamic IDO proteolysis effectively inhibits tumor growth, metastasis, and recurrence. Collectively, this study presents a promising nanomedicine, designed to synergize PROTACs with other immunotherapeutic modalities, for more effective and safer cancer immunotherapy.

Glucocorticoids-based prodrug design: Current strategies and research progress

Attributing to their broad pharmacological effects encompassing anti-inflammation, antitoxin, and immunosuppression, glucocorticoids (GCs) are extensively utilized in the clinic for the treatment of diverse diseases such as lupus erythematosus, nephritis, arthritis, ulcerative colitis, asthma, keratitis, macular edema, and leukemia. However, long-term use often causes undesirable side effects, including metabolic disorders-induced Cushing's syndrome (buffalo back, full moon face, hyperglycemia, etc.), osteoporosis, aggravated infection, psychosis, glaucoma, and cataract. These notorious side effects seriously compromise patients' quality of life, especially in patients with chronic diseases. Therefore, glucocorticoid-based advanced drug delivery systems for reducing adverse effects have received extensive attention. Among them, prodrugs have the advantages of low investment, low risk, and high success rate, making them a promising strategy. In this review, we propose the strategies for the design and summarize current research progress of glucocorticoid-based prodrugs in recent decades, including polymer-based prodrugs, dendrimer-based prodrugs, antibody-drug conjugates, peptide-drug conjugates, carbohydrate-based prodrugs, aliphatic acid-based prodrugs and so on. Besides, we also raise issues that need to be focused on during the development of glucocorticoid-based prodrugs. This review is expected to be helpful for the research and development of novel GCs and prodrugs.

Hybrid adipocyte-derived exosome nano platform for potent chemo-phototherapy in targeted hepatocellular carcinoma

The high prevalence and severity of hepatocellular carcinoma (HCC) present a significant menace to human health. Despite the significant advancements in nanotechnology-driven antineoplastic agents, there remains a conspicuous gap in the development of targeted chemotherapeutic agents specifically designed for HCC. Consequently, there is an urgent need to explore potent drug delivery systems for effective HCC treatment. Here we have exploited the interplay between HCC and adipocyte to engineer a hybrid adipocyte-derived exosome platform, serving as a versatile vehicle to specifically target HCC and exsert potent antitumor effect. A lipid-like prodrug of docetaxel (DSTG) with a reactive oxygen species (ROS)-cleavable linker, and a lipid-conjugated photosensitizer (PPLA), spontaneously co-assemble into nanoparticles, functioning as the lipid cores of the hybrid exosomes (HEMPs and NEMPs). These nanoparticles are further encapsuled within adipocyte-derived exosome membranes, enhancing their affinity towards HCC cancer cells. As such, cancer cell uptakes of hybrid exosomes are increased up to 5.73-fold compared to lipid core nanoparticles. Our in vitro and in vivo experiments have demonstrated that HEMPs not only enhance the bioactivity of the prodrug and extend its circulation in the bloodstream but also effectively inhibit tumor growth by selectively targeting hepatocellular carcinoma tumor cells. Self-facilitated synergistic drug release subsequently promoting antitumor efficacy, inducing significant inhibition of tumor growth with minimal side effects. Our findings herald a promising direction for the development of targeted HCC therapeutics.

Single Molecular Nanomedicines Based on Macrocyclic Carrier-Drug Conjugates for Concentration-Independent Encapsulation and Precise Activation of Drugs

Nanomedicines often rely on noncovalent self-assembly and encapsulation for drug loading and delivery. However, challenges such as reproducibility issues due to the multicomponent nature, off-target activation caused by premature drug release, and complex pharmacokinetics arising from assembly dissociation have hindered their clinical translation. In this study, we introduce an innovative design concept termed single molecular nanomedicine (SMNM) based on macrocyclic carrier-drug conjugates. Through the covalent linkage of two chemotherapy drugs to a hypoxia-cleavable macrocyclic carrier, azocalix[4]arene, we obtained two self-included complexes to serve as SMNMs. The intramolecular inclusion feature of the SMNMs has not only demonstrated comprehensive shielding and protection for the drugs but also effectively prevented off-target drug leakage, thereby significantly reducing their side effects and enhancing their antitumor therapeutic efficacy. Additionally, the attributes of being a single component and molecularly dispersed confer advantages such as ease of preparation and good reproducibility for SMNMs, which is desirable for clinical applications.

A convenient protonated strategy for constructing nanodrugs from hydrophobic drug-inhibitor conjugates to reverse tumor multidrug resistance

Combination therapy has proven effective in counteracting tumor multidrug resistance (MDR). However, the pharmacokinetic differences among various drugs and inherent water insolubility for most small molecule agents greatly hinder their synergistic effects, which makes the delivery of drugs for combination therapy in vivo a key problem. Herein, we propose a protonated strategy to transform a water-insoluble small molecule drug-inhibitor conjugate into an amphiphilic one, which then self-assembles into nanoparticles for co-delivery in vivo to overcome tumor MDR. Specifically, paclitaxel (PTX) is first coupled with a third-generation P-glycoprotein (P-gp) inhibitor zosuquidar (Zos) through a glutathione (GSH)-responsive disulfide bond to produce a hydrophobic drug-inhibitor conjugate (PTX-ss-Zos). Subsequently treated with hydrochloric acid ethanol solution (HCl/EtOH), PTX-ss-Zos is transformed into the amphiphilic protonated precursor and then forms nanoparticles (PTX-ss-Zos@HCl NPs) in water by molecular self-assembly. PTX-ss-Zos@HCl NPs can be administered intravenously and accumulated specifically at tumor sites. Once internalized by cancer cells, PTX-ss-Zos@HCl NPs can be degraded under the overexpressed GSH to release PTX and Zos simultaneously, which synergistically reverse tumor MDR and inhibit tumor growth. This offers a promising strategy to develop small molecule self-assembled nanoagents to reverse tumor MDR in combination therapy.

Advances of Layered Double Hydroxide-Based Materials for Tumor Imaging and Therapy

Layered double hydroxides (LDH) are a class of functional anionic clays that typically consist of orthorhombic arrays of metal hydroxides with anions sandwiched between the layers. Due to their unique properties, including high chemical stability, good biocompatibility, controlled drug loading, and enhanced drug bioavailability, LDHs have many potential applications in the medical field. Especially in the fields of bioimaging and tumor therapy. This paper reviews the research progress of LDHs and their nanocomposites in the field of tumor imaging and therapy. First, the structure and advantages of LDH are discussed. Then, several commonly used methods for the preparation of LDH are presented, including co-precipitation, hydrothermal and ion exchange methods. Subsequently, recent advances in layered hydroxides and their nanocomposites for cancer imaging and therapy are highlighted. Finally, based on current research, we summaries the prospects and challenges of layered hydroxides and nanocomposites for cancer diagnosis and therapy.

Probing the Impact of Surface Functionalization Module on the Performance of Mitoxantrone Prodrug Nanoassemblies: Improving the Effectiveness and Safety

Prodrug nanoassemblies are emerging as a novel drug delivery system for chemotherapy, comprising four fundamental modules: a drug module, a modification module, a response module, and a surface functionalization module. Among these modules, surface functionalization is an essential process to enhance the biocompatibility and stability of the nanoassemblies. Here, we selected mitoxantrone (MTO) as the drug module and DSPE-PEG2K as surface functionalization module to develop MTO prodrug nanoassemblies. We systematically evaluated the effect of surface functionalization module ratios (10%, 20%, 40%, and 60% of prodrug, WDSPE-mPEG2000/Wprodrug) on the prodrug nanoassemblies. The results indicated that 40% NPs significantly improved the self-assembly stability and cellular uptake of prodrug nanoassemblies. Compared with MTO solution, 40% NPs showed better tumor specificity and pharmacokinetics, resulting in potent antitumor activity with a good safety profile. These findings highlighted the pivotal role of the surface functionalization module in regulating the performance of mitoxantrone prodrug nanoassemblies for cancer treatment.

Sonodynamic-chemotherapy synergy with chlorin e6-based carrier-free nanoparticles for non-small cell lung cancer

Sonodynamic therapy (SDT), an emerging cancer treatment with significant potential, offers the advantages of non-invasiveness and deep tissue penetrability. The method involves activating sonosensitizers with ultrasound to generate reactive oxygen species (ROS) capable of eradicating cancer cells, addressing the challenge faced by photodynamic therapy (PDT) where conventional light sources struggle to penetrate deep tissues, impacting treatment efficacy. This study addresses prevalent challenges in numerous nanodiagnostic and therapeutic agents, such as intricate synthesis, poor repeatability, low stability, and high cost, by introducing a streamlined one-step assembly method for nanoparticle preparation. Specifically, the sonosensitizer Chlorin e6 (Ce6) and the chemotherapy drug erlotinib are effortlessly combined and self-assembled under sonication, yielding carrier-free nanoparticles (EC-NPs) for non-small cell lung cancer (NSCLC) treatment. The resulting EC-NPs exhibit optimal drug loading capacity, a simplified preparation process, and robust stability both in vitro and in vivo, owing to their carrier-free characteristics. Under the synergistic treatment of sonodynamic therapy and chemotherapy, EC-NPs induce an excess of reactive oxygen in tumor tissue, prompting apoptosis of cancer cells and reducing their proliferative capacity. Both in vitro and in vivo experiments demonstrate superior therapeutic effects of EC-NPs under ultrasound conditions compared to free Ce6. In summary, our research findings highlight that the innovatively designed carrier-free sonosensitizer EC-NPs present a therapeutic option with commendable efficacy and minimal side effects.

Self-assembled nanodrug delivery systems for anti-cancer drugs from traditional Chinese medicine

Traditional Chinese medicine (TCM) is a combination of raw herbs and herbal extracts with a plethora of documented beneficial bioactivities, which has unique advantages in anti-tumor therapy, and many of its major bioactive molecules have been identified in recent years due to advances in chemical separation and structural analysis. However, the major chemical classes of plant-derived bioactive compounds frequently possess chemical properties, including poor water solubility, stability, and bioavailability, that limit their therapeutic application. Alternatively, natural small molecules (NSMs) containing these components possess modifiable groups, multiple action sites, hydrophobic side chains, and a rigid skeleton with self-assembly properties that can be exploited to construct self-assembled nanoparticles with therapeutic effects superior to their individual constituents. For instance, the construction of a self-assembled nanodrug delivery system can effectively overcome the strong hydrophobicity and poor in vivo stability of NSMs, thereby greatly improving their bioavailability and enhancing their anti-tumor efficacy. This review summarizes the self-assembly methods, mechanisms, and applications of a variety of NSMs, including terpenoids, flavonoids, alkaloids, polyphenols, and saponins, providing a theoretical basis for the subsequent research on NSMs and the development of SANDDS.

Tetrasulfide bond boosts the anti-tumor efficacy of dimeric prodrug nanoassemblies

Dimeric prodrug nanoassemblies (DPNAs) stand out as promising strategies for improving the efficiency and safety of chemotherapeutic drugs. The success of trisulfide bonds (-SSS-) in DPNAs makes polysulfide bonds a worthwhile focus. Here, we explore the comprehensive role of tetrasulfide bonds (-SSSS-) in constructing superior DPNAs. Compared to trisulfide and disulfide bonds, tetrasulfide bonds endow DPNAs with superlative self-assembly stability, prolonged blood circulation, and high tumor accumulation. Notably, the ultra-high reduction responsivity of tetrasulfide bonds make DPNAs a highly selective "tumor bomb" that can be ignited by endogenous reducing agents in tumor cells. Furthermore, we present an "add fuel to the flames" strategy to intensify the reductive stress at tumor sites by replenishing exogenous reducing agents, making considerable progress in selective tumor inhibition. This work elucidates the crucial role of tetrasulfide bonds in establishing intelligent DPNAs, alongside the combination methodology, propelling DPNAs to new heights in potent cancer therapy.

Nanoformulations of chemotherapeutic activators of the cGAS-STING pathway in tumor chemoimmunotherapy

Chemotherapeutic drugs to activate the cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) pathway have been exploited for tumor chemoimmunotherapy. The clinical translation of chemotherapeutic cGAS-STING activators is hindered by the lack of safe, efficient, and specific delivery strategies. Nanodrug delivery systems (NDDS) designed for reducing toxic effects and improving transport effectiveness potentiate in vivo delivery of chemotherapeutic cGAS-STING activators. cGAS-STING monotherapy often encounters tumor resistance without providing satisfactory therapeutic benefit; therefore combination therapy is desirable. This review describes NDDS strategies for surmounting delivery obstacles of chemotherapeutic cGAS-STING activators and highlights combinatorial regimens, which utilize therapeutics that work by different mechanisms, for optimal therapy.

Theranostic applications of peptide-based nanoformulations for growth factor defective cancers

Growth factors play a pivotal role in orchestrating cellular growth and division by binding to specific cell surface receptors. Dysregulation of growth factor production or activity can contribute to the uncontrolled cell proliferation observed in cancer. Peptide-based nanoformulations (PNFs) have emerged as promising therapeutic strategies for growth factor-deficient cancers. PNFs offer multifaceted capabilities including targeted delivery, imaging modalities, combination therapies, resistance modulation, and personalized medicine approaches. Nevertheless, several challenges remain, including limited specificity, stability, pharmacokinetics, tissue penetration, toxicity, and immunogenicity. To address these challenges and optimize PNFs for clinical translation, in-depth investigations are warranted. Future research should focus on elucidating the intricate interplay between peptides and nanoparticles, developing robust spectroscopic and computational methodologies, and establishing a comprehensive understanding of the structure-activity relationship governing peptide-nanoparticle interactions. Bridging these knowledge gaps will propel the translation of peptide-nanoparticle therapies from bench to bedside. While a few peptide-nanoparticle drugs have obtained FDA approval for cancer treatment, the integration of nanostructured platforms with peptide-based medications holds tremendous potential to expedite the implementation of innovative anticancer interventions. Therefore, growth factor-deficient cancers present both challenges and opportunities for targeted therapeutic interventions, with peptide-based nanoformulations positioned as a promising avenue. Nonetheless, concerted research and development endeavors are essential to optimize the specificity, stability, and safety profiles of PNFs, thereby advancing the field of peptide-based nanotherapeutics in the realm of oncology research.

Satellite-Type Sulfur Atom Distribution in Trithiocarbonate Bond-Bridged Dimeric Prodrug Nanoassemblies: Achieving Both Stability and Activatability

Homodimeric prodrug nanoassemblies (HDPNs) hold promise for improving the delivery efficiency of chemo-drugs. However, the key challenge lies in designing rational chemical linkers that can simultaneously ensure the chemical stability, self-assembly stability, and site-specific activation of prodrugs. The "in series" increase in sulfur atoms, such as trisulfide bond, can improve the assembly stability of HDPNs to a certain extent, but limits the chemical stability of prodrugs. Herein, trithiocarbonate bond (─SC(S)S─), with a stable "satellite-type" distribution of sulfur atoms, is developed via the insertion of a central carbon atom in trisulfide bonds. ─SC(S)S─ bond effectively addresses the existing predicament of HDPNs by improving the chemical and self-assembly stability of homodimeric prodrugs while maintaining the on-demand bioactivation. Furthermore, ─SC(S)S─ bond inhibits antioxidant defense system, leading to up-regulation of the cellular ROS and apoptosis of tumor cells. These improvements of ─SC(S)S─ bond endow the HDPNs with in vivo longevity and tumor specificity, ultimately enhancing the therapeutic outcomes. ─SC(S)S─ bond is, therefore, promising for overcoming the bottleneck of HDPNs for efficient oncological therapy.

Biological Interaction and Imaging of Ultrasmall Gold Nanoparticles

The ultrasmall gold nanoparticles (AuNPs), serving as a bridge between small molecules and traditional inorganic nanoparticles, create significant opportunities to address many challenges in the health field. This review discusses the recent advances in the biological interactions and imaging of ultrasmall AuNPs. The challenges and the future development directions of the ultrasmall AuNPs are presented.

Targeted drug delivery strategy: a bridge to the therapy of diabetic kidney disease

Diabetic kidney disease (DKD) is the main complication in diabetes mellitus (DM) and the main cause of end-stage kidney disease worldwide. However, sodium glucose cotransporter 2 (SGLT2) inhibition, glucagon-like peptide-1 (GLP-1) receptor agonist, mineralocorticoid receptor antagonists and endothelin receptor A inhibition have yielded promising effects in DKD, a great part of patients inevitably continue to progress to uremia. Newly effective therapeutic options are urgently needed to postpone DKD progression. Recently, accumulating evidence suggests that targeted drug delivery strategies, such as macromolecular carriers, nanoparticles, liposomes and so on, can enhance the drug efficacy and reduce the undesired side effects, which will be a milestone treatment in the management of DKD. The aim of this article is to summarize the current knowledge of targeted drug delivery strategies and select the optimal renal targeting strategy to provide new therapies for DKD.

Engineering Diselenide-IR780 Homodimeric Nanoassemblies with Enhanced Photodynamic and Immunotherapeutic Effects for Triple-Negative Breast Cancer Treatment

Photodynamic therapy (PDT) has emerged as an efficient approach for non-invasive cancer treatment. However, organic small-molecule photosensitizers are often associated with defects in hydrophobicity, poor photostability, and aggregation-caused quenching, which limit their application. Usually, the carrier-assisted drug delivery system is a common strategy to solve the above obstacles, but additional carrier material could increase the risk of potential biological toxicity. The carrier-free drug delivery system with easy preparation and high drug-loading capability is proposed subsequently as a potential strategy to develop the clinical use of hydrophobic drugs. Herein, we rationally designed three IR780-based carrier-free nanosystems formed by carbon/disulfide/diselenide bond conjugated IR780-based homodimers. The IR780-based homodimers could self-assemble to form nanoparticles (DC-NP, DS-NP, DSe-NP) and exhibited higher reactive oxygen species generation capability and photostability than free IR780, in which DSe-NP with 808 nm laser irradiation performed best and resulted in the strongest cytotoxicity to 4T1 cells. Meanwhile, the glutathione consumption ability of DSe-NP boosted its PDT effect and then induced excessive oxidative stress of 4T1 cells, increasing antitumor efficacy by enhancing immunogenic cell death further. In tumor-bearing mice, DSe-NP displayed obvious tumor site accumulation, which obviously inhibited tumor growth and metastasis, and enhanced the immunological effect by effectively inducing dendritic cells to mature and activating T lymphocytes and natural killer cells. In summary, our study presented an IR780-based carrier-free nanodelivery system for a combination of PDT and immunity therapy and established expanding the application of organic small-molecule photosensitizers by an approach of carrier-free drug delivery system.

Camptothecin-based prodrug nanomedicines for cancer therapy

Camptothecin (CPT) is a cytotoxic alkaloid that attenuates the replication of cancer cells via blocking DNA topoisomerase 1. Despite its encouraging and wide-spectrum antitumour activity, its application is significantly restricted owing to its instability, low solubility, significant toxicity, and acquired tumour cell resistance. This has resulted in the development of many CPT-based therapeutic agents, especially CPT-based nanomedicines, with improved pharmacokinetic and pharmacodynamic profiles. Specifically, smart CPT-based prodrug nanomedicines with stimuli-responsive release capacity have been extensively explored owing to the advantages such as high drug loading, improved stability, and decreased potential toxicity caused by the carrier materials in comparison with normal nanodrugs and traditional delivery systems. In this review, the potential strategies and applications of CPT-based nanoprodrugs for enhanced CPT delivery toward cancer cells are summarized. We appraise in detail the chemical structures and release mechanisms of these nanoprodrugs and guide materials chemists to develop more powerful nanomedicines that have real clinical therapeutic capacities.

Self-engineered binary nanoassembly enabling closed-loop glutathione depletion-amplified tumor ferroptosis

Ferroptosis has emerged as a promising target for anticancer treatment, comprising iron-dependent lipid peroxidation and excessive accumulation of reactive oxygen species. Given that glutathione (GSH) overproduced in tumor cells antagonizes the cellular oxidation system, the reduction of GSH production has been extensively explored to induce ferroptosis. However, reducing GSH production alone is insufficient to trigger an intense lipid peroxidation storm. It is highly desirable to achieve systemic GSH depletion through simultaneous production and consumption intervention. Herein, we propose a bidirectional blockage strategy for closed-loop GSH depletion-amplified tumor ferroptosis. Sorafenib (Sor) and gambogic acid (GA) were elaborately fabricated as a self-engineered carrier-free nanoassembly without any nanocarrier materials. The PEGylated dual-drug nanoassembly enables favorable co-delivery and tumor-specific release of Sor and GA. Notably, a closed-loop GSH depletion is observed as a result of a Sor-induced decrease in GSH production and GA-accelerated GSH consumption in vitro and in vivo. As expected, this uniquely engineered dual-drug nanoassembly demonstrates vigorous antitumor activity in 4T1 breast tumor-bearing mice. This study presents a novel nanotherapeutic modality for ferroptosis-driven cancer treatment.

Smart nanoparticles for cancer therapy

Smart nanoparticles, which can respond to biological cues or be guided by them, are emerging as a promising drug delivery platform for precise cancer treatment. The field of oncology, nanotechnology, and biomedicine has witnessed rapid progress, leading to innovative developments in smart nanoparticles for safer and more effective cancer therapy. In this review, we will highlight recent advancements in smart nanoparticles, including polymeric nanoparticles, dendrimers, micelles, liposomes, protein nanoparticles, cell membrane nanoparticles, mesoporous silica nanoparticles, gold nanoparticles, iron oxide nanoparticles, quantum dots, carbon nanotubes, black phosphorus, MOF nanoparticles, and others. We will focus on their classification, structures, synthesis, and intelligent features. These smart nanoparticles possess the ability to respond to various external and internal stimuli, such as enzymes, pH, temperature, optics, and magnetism, making them intelligent systems. Additionally, this review will explore the latest studies on tumor targeting by functionalizing the surfaces of smart nanoparticles with tumor-specific ligands like antibodies, peptides, transferrin, and folic acid. We will also summarize different types of drug delivery options, including small molecules, peptides, proteins, nucleic acids, and even living cells, for their potential use in cancer therapy. While the potential of smart nanoparticles is promising, we will also acknowledge the challenges and clinical prospects associated with their use. Finally, we will propose a blueprint that involves the use of artificial intelligence-powered nanoparticles in cancer treatment applications. By harnessing the potential of smart nanoparticles, this review aims to usher in a new era of precise and personalized cancer therapy, providing patients with individualized treatment options.

Advance Progress in Assembly Mechanisms of Carrier-Free Nanodrugs for Cancer Treatment

Nanocarriers have been widely studied and applied in the field of cancer treatment. However, conventional nanocarriers still suffer from complicated preparation processes, low drug loading, and potential toxicity of carriers themselves. To tackle the hindrance, carrier-free nanodrugs with biological activity have received increasing attention in cancer therapy. Extensive efforts have been made to exploit new self-assembly methods and mechanisms to expand the scope of carrier-free nanodrugs with enhanced therapeutic performance. In this review, we summarize the advanced progress and applications of carrier-free nanodrugs based on different types of assembly mechanisms and strategies, which involved noncovalent interactions, a combination of covalent bonds and noncovalent interactions, and metal ions-coordinated self-assembly. These carrier-free nanodrugs are introduced in detail according to their assembly and antitumor applications. Finally, the prospects and existing challenges of carrier-free nanodrugs in future development and clinical application are discussed. We hope that this comprehensive review will provide new insights into the rational design of more effective carrier-free nanodrug systems and advancing clinical cancer and other diseases (e.g., bacterial infections) infection treatment.

The improving strategies and applications of nanotechnology-based drugs in hepatocellular carcinoma treatment

Hepatocellular carcinoma (HCC) is one of the leading causes of tumor-related death worldwide. Conventional treatments for HCC include drugs, radiation, and surgery. Despite the unremitting efforts of researchers, the curative effect of HCC has been greatly improved, but because HCC is often found in the middle and late stages, the curative effect is still not satisfactory, and the 5-year survival rate is still low. Nanomedicine is a potential subject, which has been applied to the treatment of HCC and has achieved promising results. Here, we summarized the factors affecting the efficacy of drugs in HCC treatment and the strategies for improving the efficacy of nanotechnology-based drugs in HCC, reviewed the recent applications' progress on nanotechnology-based drugs in HCC treatment, and discussed the future perspectives and challenges of nanotechnology-based drugs in HCC treatment.

Folate-receptor-targeted co-self-assembly carrier-free gemcitabine nanoparticles loading indocyanine green for chemo-photothermal therapy

The carrier-free chemo-photothermal therapy has become a promising strategy to improve anti-cancer therapeutic efficacy owing to the combination of chemotherapy and photothermal therapy, with improved chemotherapy drug pharmacodynamics and pharmacokinetics, high drug loading, and reduced toxicity. We designed a novel carrier-free targeting nanoparticles, co-self-assembled amphiphilic prodrugs 3',5'-dioleoyl gemcitabine (DOG), and tumor-targeted γ-octadecyl folate (MOFA), with encapsulated US Food and Drug Administration (FDA)-approved photosensitizer indocyanine green (ICG) for synergistic chemo-photothermal therapy. The DOG linking oleic acid to the sugar moiety of gemcitabine (GEM) showed better self-assembly ability among GEM amphiphilic prodrugs linking different fatty acids. The readily available and highly reproducible 3',5'-dioleoyl gemcitabine/γ-octadecyl folate/indocyanine green (DOG/MOFA/ICG) nanoparticles were prepared by reprecipitation and showed nano-scale structure with mono-dispersity, great encapsulation efficiency of ICG (approximately 74%), acid- and laser irradiation-triggered GEM release in vitro and sustained GEM release in vivo after intravenous administration as well as excellent temperature conversion (57.0°C) with near-infrared laser irradiation. The combinational DOG/MOFA/ICG nanoparticles with near-infrared laser irradiation showed better anti-tumor efficacy than individual chemotherapy or photothermal therapy, with very low hemolysis and inappreciable toxicity for L929 cells. This co-self-assembly of the ICG and the chemotherapy drug (GEM) provides a novel tactic for the rational design of multifunctional nanosystems for targeting drug delivery and theranostics.

Nanosized Assemblies from Amphiphilic Solanesol Derivatives for Anticancer Drug Delivery

Unexpected functionalities of pharmaceutical excipients have been found in some cases. Preplanned introduction of excipients with therapeutic effects might not only reduce the risks of metabolism-related toxicity but also provide synergistic therapeutic effects. Herein, natural original solanesol (SOL), one of the isoprene compounds with some pharmacological activities, was selected to prepare a series of amphiphilic derivatives by chemical modification, and drug delivery systems for oncotherapy were established. Three derivatives, including solanesyl bromide (SOL-Br), monosolanesolsolanesyl succinate (MSS), and solanesylthiosalicylate (STS), were synthesized and formulated into nanosized self-assemblies for doxorubicin (DOX) encapsulation. Meanwhile, polyethylene glycol (PEG) derivatives were synthesized as the stabilizer of solanesol-based self-assemblies, among which hydrazine-poly(ethylene glycol)-hydrazine (PEG6000-DiHZ) was found to be more reliable. The optimized molar ratio between PEG6000-DiHZ and solanesol derivatives was found to be 2:1, considering the drug-loading capacity of self-assemblies. Consistent release profiles were found for the DOX-loaded self-assemblies, in which about 75-80% DOX was cumulatively released within 60 h at pH 5.0. The three DOX-loaded self-assemblies were found to be homogeneous spheres with average particle sizes in the range of 100-200 nm by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Blank self-assemblies were found to have an inhibiting ability toward MCF-7 and HepG-2 cancer cells, which might originate from the inherent nature of solanesol derivatives. In vivo pharmacodynamic experiments demonstrated that blank self-assemblies had certain inhibitory effect on tumor growth compared with the controls. Further enhanced effects were also found for the drug-loaded self-assemblies due to the synergistic anti-tumor effect existing between the drug and the carriers. This work has presented a simple and effective strategy to prepare a therapeutic carrier by direct assembling of the therapeutic compound without PEGylation steps, by which the therapeutic carrier materials could take their effect directly and synergistically along with the loaded drugs.

Emerging platinum(IV) prodrug nanotherapeutics: A new epoch for platinum-based cancer therapy

Owing to the unique DNA damaging cytotoxicity, platinum (Pt)-based chemotherapy has long been the first-line choice for clinical oncology. Unfortunately, Pt drugs are restricted by the severe dose-dependent toxicity and drug resistance. Correspondingly, Pt(IV) prodrugs are developed with the aim to improve the antitumor performance of Pt drugs. However, as "free" molecules, Pt(IV) prodrugs are still subject to unsatisfactory in vivo destiny and antitumor efficacy. Recently, Pt(IV) prodrug nanotherapeutics, inheriting both the merits of Pt(IV) prodrugs and nanotherapeutics, have emerged and demonstrated the promise to address the underexploited dilemma of Pt-based cancer therapy. Herein, we summarize the latest fronts of emerging Pt(IV) prodrug nanotherapeutics. First, the basic outlines of Pt(IV) prodrug nanotherapeutics are overviewed. Afterwards, how versatile Pt(IV) prodrug nanotherapeutics overcome the multiple biological barriers of antitumor drug delivery is introduced in detail. Moreover, advanced combination therapies based on multimodal Pt(IV) prodrug nanotherapeutics are discussed with special emphasis on the synergistic mechanisms. Finally, prospects and challenges of Pt(IV) prodrug nanotherapeutics for future clinical translation are spotlighted.

Combination therapy to overcome ferroptosis resistance by biomimetic self-assembly nano-prodrug

Ferroptosis has emerged as a potent form of no-apoptotic cell death that offers a promising alternative to avoid the chemoresistance of apoptotic pathways and serves as a vulnerability of cancer. Herein, we have constructed a biomimetic self-assembly nano-prodrug system that enables the co-delivery of gefitinib (Gefi), ferrocene (Fc) and dihydroartemisinin (DHA) for the combined therapy of both ferroptosis and apoptosis. In the tumor microenvironment, this nano-prodrug is able to disassemble and trigger drug release under high levels of GSH. Interestingly, the released DHA can downregulate GPX4 level for the enhancement of intracellular ferroptosis from Fc, further executing tumor cell death with concomitant chemotherapy by Gefi. More importantly, this nano-prodrug provides highly homologous targeting ability by coating related cell membranes and exhibits outstanding inhibition of tumor growth and metastasis, as well as no noticeable side-effects during treatments. This simple small molecular self-assembled nano-prodrug provides a new reasonably designed modality for ferroptosis-combined chemotherapy.

Bio-inspired self-assembled bacteriochlorin nanoparticles for superior visualization and photothermal ablation of tumors

BACKGROUND

Although hyperthermia-based photothermal therapy (PTT) has achieved great success in the battle against malignant tumors, various commonly used photothermal sensitizers still suffer from non-selective tumor accumulation, limited photothermal conversion efficiency, potential toxicity and side effects, as well as complex and low cost-effective preparation process. Therefore, novel photothermal sensitizers are urgently required. The well-organized self-assembling of natural bacteriochlorophylls with superior photothermal property may provide an interesting option for the engineering of ideal PTS.

METHODS

Inspired by the self-assembly peripheral light-harvesting antennas of natural bacteriochlorin in microorganisms, a biomimetic light-harvesting nanosystem (Nano-Bc) was developed via bacteriochlorophylls self-arranging in aqueous phase. The characterization of Nano-Bc were measured using DLS, TEM, UV-vis-near-infrared spectroscopy and preclinical PA imaging system. The cytotoxicity of Nano-Bc was quantitatively evaluated via a standard MTT assay using mouse breast cancer 4T1 cells, and the in vivo photothermal eradication of tumor was investigated in the 4T1 breast tumor-bearing mouse model.

RESULTS

The obtained bacteriochlorin nanoparticles (Nano-Bc) exhibited ultra-high photothermal performance within the biological transparent window, showing superior heating capacity compared to commonly used photothermal sensitizers of organic dye indocyanine green and inorganic gold nanorods. Guiding by the inherent photoacoustic imaging of Nano-Bc, complete tumor elimination in vitro and vivo was evidenced upon laser irradiation.

CONCLUSION

The green and facile preparation, ultra-high photothermal effect in the transparent window, excellent photoacoustic imaging capacity, and great biosafety prompt, the bio-inspired Nano-Bc as a promising theranostic platform against cancer in the areas of healthcare.

In situ stimulus-responsive self-assembled nanomaterials for drug delivery and disease treatment

The individual motifs that respond to specific stimuli for the self-assembly of nanomaterials play important roles. In situ constructed nanomaterials are formed spontaneously without human intervention and have promising applications in bioscience. However, due to the complex physiological environment of the human body, designing stimulus-responsive self-assembled nanomaterials in vivo is a challenging problem for researchers. In this article, we discuss the self-assembly principles of various nanomaterials in response to the tissue microenvironment, cell membrane, and intracellular stimuli. We propose the applications and advantages of in situ self-assembly in drug delivery and disease diagnosis and treatment, with a focus on in situ self-assembly at the lesion site, especially in cancer. Additionally, we introduce the significance of introducing exogenous stimulation to construct self-assembly in vivo. Based on this foundation, we put forward the prospects and possible challenges in the field of in situ self-assembly. This review uncovers the relationship between the structure and properties of in situ self-assembled nanomaterials and provides new ideas for innovative drug molecular design and development to solve the problems in the targeted delivery and precision medicine.

Redox-Responsive Lipidic Prodrug Nano-Delivery System Improves Antitumor Effect of Curcumin Derivative C210

The poor bioavailability of curcumin and its derivatives limits their antitumor efficacy and clinical translation. Although curcumin derivative C210 has more potent antitumor activity than curcumin, it has a similar deficiency to curcumin. In order to improve its bioavailability and accordingly enhance its antitumor activity in vivo, we developed a redox-responsive lipidic prodrug nano-delivery system of C210. Briefly, we synthesized three conjugates of C210 and oleyl alcohol (OA) via different linkages containing single sulfur/disulfide/carbon bonds and prepared their nanoparticles using a nanoprecipitation method. The prodrugs required only a very small amount of DSPE-PEG2000 as a stabilizer to self-assemble in aqueous solution to form nanoparticles (NPs) with a high drug loading capacity (~50%). Among them, the prodrug (single sulfur bond) nanoparticles (C210-S-OA NPs) were the most sensitive to the intracellular redox level of cancer cells; therefore, they could rapidly release C210 in cancer cells and thus had the strongest cytotoxicity to cancer cells. Furthermore, C210-S-OA NPs exerted a dramatic improvement in its pharmacokinetic behavior; that is, the area under the curve (AUC), mean retention time and accumulation in tumor tissue were 10, 7 and 3 folds that of free C210, respectively. Thus, C210-S-OA NPs exhibited the strongest antitumor activity in vivo than C210 or other prodrug NPs in mouse models of breast cancer and liver cancer. The results demonstrated that the novel prodrug self-assembled redox-responsive nano-delivery platform was able to improve the bioavailability and antitumor activity of curcumin derivative C210, which provides a basis for further clinical applications of curcumin and its derivatives.

Redox-responsive drug-inhibitor conjugate encapsulated in DSPE-PEG2k micelles for overcoming multidrug resistance to chemotherapy

Multidrug resistance (MDR) is a major cause of chemotherapy failure in cancer treatment. P-glycoprotein (P-gp) inhibitors are helpful for chemotherapy drugs to overcome tumor MDR effectively. With the traditional physical mixing of chemotherapy drugs and inhibitors, it is difficult to achieve satisfactory results due to the different pharmacokinetics and physicochemical properties between the two of them. Herein, we prepared a novel drug-inhibitor conjugate prodrug (PTX-ss-Zos) from a cytotoxin (PTX) and a third-generation P-gp inhibitor (Zos) linked with a redox-responsive disulfide. Then, PTX-ss-Zos was encapsulated in DSPE-PEG_2k micelles to form stable and uniform nanoparticles (PTX-ss-Zos@DSPE-PEG_2k NPs). PTX-ss-Zos@DSPE-PEG_2k NPs could be cleaved by the high-concentration GSH in cancer cells and release PTX and Zos simultaneously to inhibit MDR tumor growth synergistically without apparent systemic toxicity. The in vivo evaluation experiments exhibited that the tumor inhibition rates (TIR) of PTX-ss-Zos@DSPE-PEG_2k NPs were high up to 66.5% for HeLa/PTX tumor-bearing mice. This smart nanoplatform would bring new hope for cancer treatment in clinical trials.

Nano Delivery of Chemotherapeutic ICD Inducers for Tumor Immunotherapy

Immunogenic cell death (ICD, also known as immunogenic apoptosis) of malignant cells is confirmed to activate the host immune system to prevent, control, and eliminate tumors. Recently, a range of chemotherapeutic drugs have been repurposed as ICD inducers and applied for tumor immunotherapy. However, several hurdles to the widespread application of chemotherapeutic ICD inducers remain, namely poor water solubility, short blood circulation, non-specific tissue distribution, and severe toxicity. Recent advances in nanotechnology and pharmaceutical formulation foster the development of nano drug delivery systems to tackle the aforementioned hurdles and expedite safe, effective, and specific delivery. This review will describe delivery barriers to chemical ICD inducers and highlight recent nanoformulations for these drugs in tumor immunotherapy.

Lipid Prodrug Nanoassemblies via Dynamic Covalent Boronates

Prodrug nanoassemblies combine the advantages of prodrug and nanomedicines, offering great potential in targeting the lesion sites and specific on-demand drug release, maximizing the therapeutic performance while minimizing their side effects. However, there is still lacking a facile pathway to prepare the lipid prodrug nanoassemblies (LPNAs). Herein, we report the LPNAs via the dynamic covalent boronate between catechol and boronic acid. The resulting LPNAs possess properties like drug loading in a dynamic covalent manner, charge reversal in an acidic microenvironment, and specific drug release at an acidic and/or oxidative microenvironment. Our methodology enables the encapsulation and delivery of three model drugs: ciprofloxacin, bortezomib, and miconazole. Moreover, the LPNAs are often more efficient in eradicating pathogens or cancer cells than their free counterparts, both in vitro and in vivo. Together, our LPNAs with intriguing properties may boost the development of drug delivery and facilitate their clinical applications.

Carboxylated paclitaxel prodrug nanofibers for enhanced chemotherapy

The facile availability of nanoformulations with enhanced antitumor performance remains a big challenge. Herein, we synthesize paclitaxel prodrugs with amphiphilic structures and robust assembling ability. Carboxylated paclitaxel prodrugs (PSCB) containing disulfide bonds prefer to form exquisite nanofibers, while phenylcarbinol end capped paclitaxel prodrugs (PSP) assemble into spherical nanoparticles. The transformation of morphology from nanofibers to nanorods can be realized via tuning the content of paclitaxel. Hydrophilic domains of PSCB nanofibers accelerate the cleavage of disulfide bond for rapid drug release in tumor cells, thus exhibiting the enhanced cytotoxicity and antitumor activity. This study provides a crucial insight into the functional design of hydrophobic drugs to improve chemotherapy.

Gold Nanoparticles as Drug Carriers: The Role of Silica and PEG as Surface Coatings in Optimizing Drug Loading

The use of gold nanoparticles as drug delivery systems has received increasing attention due to their unique properties, such as their high stability and biocompatibility. However, gold nanoparticles have a high affinity for proteins, which can result in their rapid clearance from the body and limited drug loading capabilities. To address these limitations, we coated the gold nanoparticles with silica and PEG, which are known to improve the stability of nanoparticles. The synthesis of the nanoparticles was carried out using a reduction method. The nanoparticles' size, morphology, and drug loading capacity were also studied. The SEM images showed a spherical and homogeneous morphology; they also showed that the coatings increased the average size of the nanoparticles. The results of this study provide insight into the potential of gold nanoparticles coated with silica and PEG as drug delivery systems. We used ibuprofen as a model drug and found that the highest drug load occurred in PEG-coated nanoparticles and then in silica-coated nanoparticles, while the uncoated nanoparticles had a lower drug loading capacity. The coatings were found to significantly improve the stability and drug load properties of the nanoparticles, making them promising candidates for further development as targeted and controlled release drug delivery systems.

A novel ROS-activable self-immolative prodrug for tumor-specific amplification of oxidative stress and enhancing chemotherapy of mitoxantrone

Reactive oxygen species (ROS) as well-known endogenous stimuli has been widely used to activate drug delivery systems (DDSs) for tumor-specific therapy. Unfortunately, endogenous ROS in the tumor microenvironment (TME) is not enough to achieve effective therapeutic efficacy and cancer cells have adapted to high oxidative stress by upregulating glutathione (GSH) level. Herein, we devised a novel ROS-activable self-immolative prodrug CASDB with both GSH-depletion ability and ROS self-supply competence. Then, an stimuli-responsive nanoplatform integrating CASDB with clinical chemotherapeutics mitoxantrone (MTO) and PLGA was fabricated (denoted as CMPs) through nanoprecipitation method. The CMPs could achieve desired accumulation at tumor tissues through enhanced permeability and retention (EPR) effects. Then the accumulated CMPs could induce tumor cell apoptosis efficiently. Especially, ROS in tumor sites could trigger the immolation of CASDB to generate CA and quinone methide (QM). Then CA and QM cooperatively promoted damage of mitochondria due to oxidative stress and led to cancer cells more sensitive to MTO. Accordingly, MTO could perturb cellular microenvironment of cancer cells then promote the degradation of CASDB. The experiment results demonstrated that CMPs were ideal for desirable synergetic tumor-specific anticancer therapy with negligible systemic toxicity. The half-maximal inhibitory concentrations (IC50) value of CMPs was 6.53 μM, while the IC50 values of MTO was 14.76 μM. And the CMPs group showed the strongest tumor suppressor effect with the tumor sizes increased to 1.2-fold (Control group: 20.6-fold, MTO only: 3.0-fold). This study should be inspirational for designing efficient prodrugs to overcome the handicaps of traditional chemotherapy.

Precise engineering of disulfide bond-bridged prodrug nanoassemblies to balance antitumor efficacy and safety

Prodrug-based nanoassemblies, which combine the merits of prodrug technology and nanocarriers, are regarded as promising platforms for cancer treatment. Notably, the chemical structure of prodrugs is closely associated with antitumor efficacy and safety, and the intrinsic relationships among them need further exploration. Herein, paclitaxel was conjugated with 2-octyldodecan-1-ol through different positions of disulfide bond to construct the prodrug nanoassemblies. Interestingly, the minor differences in chemical structure not only dominated the assembly performance and drug release of nanoassemblies, but also significantly impacted the pharmacokinetics, antitumor efficacy, and safety. It was worth noting that prodrug nanoassemblies with one carbon atom between disulfide bond and ester bond had faster drug release and better antitumor effect, while prodrug nanoassemblies with three carbon atoms between disulfide bond and ester bond possessed moderate antitumor effect and better safety. Our findings illustrated the structure-function relationships of self-assembled prodrugs and provided a promising paradigm for the precise engineering of advanced prodrug nanoplatforms. STATEMENT OF SIGNIFICANCE: 1. The major effects of minor differences in prodrug chemical structure on pharmacodynamics and safety were explored, which had important clinical reference significance and value. 2. The in-depth exploration of structure-function relationships to balance efficacy and safety had important guiding significance for the design of prodrug nanoassemblies.

Reduction-responsive worm-like nanoparticles for synergistic cancer chemo-photodynamic therapy

Chemo-photodynamic therapy shows great potential for cancer treatment. However, the rational integration of chemotherapeutic agents and photosensitizers to construct an intelligent nanoplatform with synergistic therapeutic effect is still a great challenge. In this work, curcumin-loaded reduction-responsive prodrug nanoparticles of new indocyanine green (Cur@IR820-ss-PEG) were developed for synergistic cancer chemo-photodynamic therapy. Cur@IR820-ss-PEG exhibit high drug loading content and special worm-like morphology, contributing to their efficient cellular uptake. Due to the presence of the disulfide bond between IR820 and PEG, Cur@IR820-ss-PEG display reduction responsive drug release behaviors. The efficient cellular uptake and reduction triggered drug release of Cur@IR820-ss-PEG lead to their enhanced in vitro cytotoxicity against 4T1cells as compared to the mixture of IR820 and curcumin (IR820/Cur) under laser irradiation. Besides, Cur@IR820-ss-PEG exhibit prolonged blood half-life time, better tumor accumulation and retention, enhanced tumor hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial cell growth factor (VEGF) suppression effect as compared to IR820/Cur. In vivo antitumor activity study, Cur@IR820-ss-PEG effectively inhibit the tumor angiogenesis, which potentiates the PDT efficacy and leads to the best in vivo antitumor effect of Cur@IR820-ss-PEG. This work provides a novel and relatively simple strategy for synergistic cancer chemo-photodynamic therapy.

Disulfide Bond-Based SN38 Prodrug Nanoassemblies with High Drug Loading and Reduction-Triggered Drug Release for Pancreatic Cancer Therapy

Purpose

Chemotherapy is a significant and effective therapeutic strategy that is frequently utilized in the treatment of cancer. Small molecular prodrug-based nanoassemblies (SMPDNAs) combine the benefits of both prodrugs and nanomedicine into a single nanoassembly with high drug loading, increased stability, and improved biocompatibility.

Methods

In this study, a disulfide bond inserted 7-ethyl-10-hydroxycamptothecin (SN38) prodrug was rationally designed and then used to prepare nanoassemblies (SNSS NAs) that were selectively activated by rich glutathione (GSH) in the tumor site. The characterization of SNSS NAs and the in vitro and in vivo evaluation of their antitumor effect on a pancreatic cancer model were performed.

Results

In vitro findings demonstrated that SNSS NAs exhibited GSH-induced SN38 release and cytotoxicity. SNSS NAs have demonstrated a passive targeting effect on tumor tissues, a superior antitumor effect compared to irinotecan (CPT-11), and satisfactory biocompatibility with double dosage treatment.

Conclusion

The SNSS NAs developed in this study provide a new method for the preparation of SN38-based nano-delivery systems with improved antitumor effect and biosafety.

Dynamic tagging to drive arginine nano-assembly to metabolically potentiate immune checkpoint blockade therapy

L-arginine metabolism is essential for the activation, survival, and effector function of the T lymphocytes and critical in eliminating tumors via T-cell-mediated immunotherapy, such as immune checkpoint blockade (ICB). Unfortunately, efficient delivery of hydrophilic L-arginine to the tumor microenvironment (TME) has met tremendous difficulties because of the limited loading efficacy and rapid diffusion. Inspired by the small-molecule prodrug nanoassemblies with ultrahigh drug-loading, we screen out aromatic aldehydes compounds to be used as dynamic tags to decorate L-arginine (reversible imine). Nano-Arginine (ArgNP, 104 nm) was created based on dynamic tag-mediated self-assembly. Molecular dynamics simulations indicate that the driving force of this self-assembly process is intermolecular hydrogen bonds, π-π stacking, and cation-π interactions. Notably, ArgNP metabolic synergy with anti-PD-L1 antibody (aPDL1) can promote tumor-infiltrating T cells (3.3-fold than aPDL1), resulting in a tumor inhibition ratio of 2.6-fold than aPDL1. Besides, such a strategy efficiently reduces the myeloid-derived suppressor cells, increases the M1-macrophages against the tumor, and induces the production of memory T cells. Furthermore, this synergistic therapy effectively restrains lung metastasis and prolongs mouse survival (60% survival ratio). The study highlights the dynamic tags strategy with facility and advance to deliver L-arginine that can metabolically promote ICB therapy.

Colloidal Polyelectrolyte Complexes from Hyaluronic Acid: Preparation and Biomedical Applications

Hyaluronic acid (HA) is a naturally occurring polysaccharide which has been extensively exploited in biomedical fields owing to its outstanding biocompatibility. Self-assembly of HA and polycations through electrostatic interactions can generate colloidal polyelectrolyte complexes (PECs), which can offer a wide range of applications while being relatively simple to prepare with rapid and "green" processes. The advantages of colloidal HA-based PECs stem from the combined benefits of nanomedicine, green chemistry, and the inherent properties of HA, namely high biocompatibility, biodegradability, and biological targeting capability. Accordingly, colloidal PECs from HA have received increasing attention in the recent years as high-performance materials for biomedical applications. Considering their potential, this review is aimed to provide a comprehensive understanding of colloidal PECs from HA in complex with polycations, from the most fundamental aspects of the preparation process to their various biomedical applications, notably as nanocarriers for delivering small molecule drugs, nucleic acids, peptides, proteins, and bioimaging agents or the construction of multifunctional platforms.

Emerging platinum(0) nanotherapeutics for efficient cancer therapy

Platinum (Pt)-based chemotherapy has been necessary for clinical cancer treatment. However, traditional bivalent drugs are hindered by poor physicochemical properties, severe toxic side effects, and drug resistance. Currently, elemental Pt(0) nanotherapeutics (NTs) have emerged to tackle the dilemma. The inherent acid-responsiveness of Pt(0) NTs could help to improve tumor selectivity and alleviate toxic effects. Moreover, the metal nature of Pt facilitates the great combination of Pt(0) NTs with photothermal and photodynamic therapy and imaging-guided diagnosis. Based on recent important researches, this review provides an updated introduction to Pt(0) NTs. First, the challenges of traditional Pt-based chemotherapy have been outlined. Then, Pt(0) NTs with multiple applications of tumor theranostics have been overviewed. Furthermore, the combinations of Pt(0) NTs with other therapeutical modalities are introduced. Last but not least, we envision the possible challenges and prospects associated with Pt(0) NTs.

Improving cellular uptake and bioavailability of periplocymarin-linoleic acid prodrug by combining PEGylated liposome

Periplocymarin (PPM), a cardiac glycoside isolated from Cortex periplocae, has a strong anti-tumor effect against various cancer cells. However, cardiotoxicity and rapid metabolism hinder its clinical applications. In this study, small molecule prodrug was integrated into PEGylated liposome to improve the efficiency of periplocymarin in vivo. The periplocymarin-linoleic acid (PL) prodrug was constructed by conjugating the linoleic acid with PPM via esterification, which was further facilitated to form PEGylated liposome (PL-Lip) through film dispersion. Compared with PL self-assembling nano-prodrug (PL-SNP), PL-Lip showed better colloid stability, sustained drug release kinetics, and enhanced cellular uptake by tumor cells. Notably, PL-Lip performed better than PPM and PL-SNP in terms of tumor distribution and pharmacokinetics, which include bioavailability and half-life. Altogether, the prodrug PEGylated liposome represents a good strategy and method for long-circulating and tumor-targeting delivery of periplocymarin with enhanced clinical application prospect.