Amphiphilic Drug Conjugates as Nanomedicines for Combined Cancer Therapy

Nanomedicine facilitated cell signaling blockade: difficulties and strategies to overcome glioblastoma

Glioblastoma (GBM) is a highly aggressive and lethal type of brain tumor with complex and diverse molecular signaling pathways involved that are in its development and progression. Despite numerous attempts to develop effective treatments, the survival rate remains low. Therefore, understanding the molecular mechanisms of these pathways can aid in the development of targeted therapies for the treatment of glioblastoma. Nanomedicines have shown potential in targeting and blocking signaling pathways involved in glioblastoma. Nanomedicines can be engineered to specifically target tumor sites, bypass the blood-brain barrier (BBB), and release drugs over an extended period. However, current nanomedicine strategies also face limitations, including poor stability, toxicity, and low therapeutic efficacy. Therefore, novel and advanced nanomedicine-based strategies must be developed for enhanced drug delivery. In this review, we highlight risk factors and chemotherapeutics for the treatment of glioblastoma. Further, we discuss different nanoformulations fabricated using synthetic and natural materials for treatment and diagnosis to selectively target signaling pathways involved in GBM. Furthermore, we discuss current clinical strategies and the role of artificial intelligence in the field of nanomedicine for targeting GBM.

A manual controlled theranostic nanoplatform with real-time photoacoustic quantification of drug release for chemophotothermal therapy

The development of intelligent nanodrug delivery systems that can visually guide the on-demand quantitative control of drug release has received extensive attention. Herein, two chemotherapeutic drugs, gallic acid and 5-fluorouracil, and Fe(III) were selected to prepare nanomedicine GF-Fe via polyphenol-metal self-assembly and infinite coordination of drug-metal. GF-Fe has good biocompatibility, photothermal properties and photoacoustic (PA) signals. When deferoxamine (DFO) was artificially applied and interacted with GF-Fe, GF-Fe began to disassemble, gallic acid and 5-fluorouracil were gradually released, while the PA signal of the nanomedicine decayed synchronously. Based on this, the relationship between the intensity of the PA signal and the drug release amount was established, so as to realize the precise quantitative control of the drug release in real-time under the guidance of PA imaging. Besides, the combined effect of the two therapeutic drugs in combination with photothermal therapy (PTT) can improve the therapeutic effect, resulting in significant superadditiveness. This nanoplatform constructed by facile synthesis provided good clinical translation potential for the implementation of precise multimodal combination therapy strategies for tumors.

The construction of hierarchical assemblies with in situ generation of chemotherapy drugs to enhance the efficacy of chemodynamic therapy for multi-modal anti-tumor treatments

The effectiveness of chemodynamic therapy (CDT) in cancer treatment is limited by insufficient endogenous H2O2 levels in tumor tissue and an increasing ratio of high valence metal ions. To overcome these challenges, a novel nanotherapeutic approach, named GOx-CuCaP-DSF, has been proposed. This approach involves the design of nanotherapeutics that aim to self-supply H2O2 within cancer cells and provide a supplement of low valence metal ions to enhance the performance of CDT. GOx-CuCaP-DSF nanotherapeutics are engineered by incorporating glucose oxidase (GOx) into Ca2+-doped calcium phosphate (CaP) nanoparticles and loading disulfiram (DSF) through surface adsorption. Under the tumor microenvironment, GOx catalyzes the conversion of tumor-overexpressed glucose (Glu) to liberate H2O2. The degradation of CaP further lowers the pH, facilitating the release of Cu2+ ions and DSF. The rapid reaction between Cu2+ and DSF leads to the generation of Cu+, increasing the Cu+/Cu2+ ratio and promoting the Cu+-based Fenton reaction, which enhances the efficiency of CDT. Simultaneously, DSF undergoes conversion to diethyldithiocarbamate acid (ET), forming a copper(II) complex (Cu(II)ET) by strong chelation with Cu ions. This Cu(II)ET complex, a potent chemotherapeutic drug, exhibits a synergistic therapeutic effect in combination with CDT. Moreover, the elevated Cu+ species resulting from DSF reaction promotes the aggregation of toxic mitochondrial proteins, leading to cell cuproptosis. Overall, the strategy of integrating the chemodynamic therapy efficiency of the Fenton reaction with the activation of efficacious cuproptosis using a chemotherapeutic drug presents a promising avenue for enhancing the effectiveness of multi-modal anti-tumor treatments.

Aspirin-Induced Ordering and Faster Dynamics of a Cationic Bilayer for Drug Encapsulation

The lipid dynamics and phase play decisive roles in drug encapsulation and delivery to the intracellular target. Thus, understanding the dynamic and structural alterations of membranes induced by drugs is essential for targeted delivery. To this end, united-atom molecular dynamics simulations of a model bilayer, dioctadecyldimethylammonium bromide (DODAB), are performed in the absence and presence of the usual nonsteroidal anti-inflammatory drug (NSAID), aspirin, at 298, 310, and 345 K. At 298 and 310 K, the bilayers are in the interdigitated two-dimensional square phases, which become rugged in the presence of aspirin, as evident from height fluctuations. At 345 K, the bilayer is in the fluid phase in both the absence and presence of aspirin. Aspirin is preferentially located near the oppositely charged headgroup and creates void space, which leads to an increase in the interdigitation and order parameters. Although the center of mass of lipids experiences structural arrest, they reach the diffusive regime faster and have higher lateral diffusion constants in the presence of aspirin. Results are found to be consistent with recent quasi-elastic neutron scattering studies that reveal that aspirin acts as a plasticizer and enhances lateral diffusion of lipids in both ordered and fluid phases. Different relaxation time scales of the bonds along the alkyl tails of DODAB due to the multitude of lipid motions become faster upon the addition of aspirin. Our results show that aspirin insertion is most favorable at physiological temperature. Thus, the ordered, more stable, and faster DODAB bilayer can be a potential drug carrier for the protected encapsulation of aspirin, followed by targeted and controlled drug release with antibacterial activity in the future.

Preparation and Cytotoxicity Evaluation of Folic Acid-Modified YF8-OA Self-Assembled Lipid Prodrug Nanoparticles

This study aimed to improve the use of YF8, a matrine derivative obtained through chemical transformation of matrine extracted from Sophora alopecuroides. YF8 has demonstrated improved cytotoxicity compared to matrine, but its hydrophobic nature hinders its application. To overcome this, the lipid prodrug YF8-OA was synthesized by linking oleic acid (OA) to YF8 through an ester bond. Although YF8-OA could self-assemble into unique nanostructures in water, it was not sufficiently stable. To enhance the stability of YF8-OA lipid prodrug nanoparticles (LPs), we employed the strategy of PEGylation using DSPE-mPEG₂₀₀₀ or DSPE-mPEG₂₀₀₀ conjugated with folic acid (FA). This resulted in the formation of uniform spherical nanoparticles with greatly improved stability and a maximum drug load capacity upto 58.63%. Cytotoxicity was evaluated in A549, HeLa, and HepG2 cell lines. The results showed that in HeLa cells, the IC₅₀ value of YF8-OA/LPs with FA-modified PEGylation was significantly lower than that of YF8-OA/LPs modified by PEGylation alone. However, no significant enhancement was observed in A549 and HepG2 cells. In conclusion, the lipid prodrug YF8-OA can form nanoparticles in aqueous solution to address its poor water solubility. Modification with FA resulted in further enhanced cytotoxicity, providing a potential avenue for exerting the antitumor activity of matrine analogs.

Target Embolization Combined with Multimodal Thermal Ablation for Solid Tumors by Smart Poly(amino acid)s Nanocomposites

Noninterventional embolization does not require the use of a catheter, and the treatment of solid tumors in combination with thermal ablation can avoid some of the risks of the surgical procedure. Therefore, we developed an efficient tumor microenvironment-gelled nanocomposites with poly [(l-glutamic acid-ran-l-tyrosine)-b-l-serine-b-l-cysteine] (PGTSCs) coated-nanoparticles (Fe₃O₄&Au@PGTSCs), from which the prepared PGTSCs were given possession of pH response to an acidic tumor microenvironment. Fe₃O₄&Au@PGTSC in noninterventional embolization treatment not only achieved the smart targeted medicine delivery but also meshed with noninvasive multimodal thermal ablation therapy and multimodal imaging of solid tumors via intravenous injection. It was worth noting that the results of animal experiments in vivo demonstrated that Fe₃O₄&Au@PGTSCs have specific tumor accumulation and embolization and thermal ablation effects; at 10 days postinjection, only scars were found at the tumor site. After 20 days, the tumors of model mice completely disappeared. This device is easier to treat solid tumors based on the slightly acidic tumor environment.

Modulating tumor-stromal crosstalk via a redox-responsive nanomedicine for combination tumor therapy

Interaction between carcinoma-associated fibroblasts (CAFs) and tumor cells leads to the invasion and metastasis of breast cancer. Herein, we prepared a redox-responsive chondroitin sulfate (CS)-based nanomedicine, in which hydrophobic cabazitaxel (CTX) was conjugated to the backbone of CS via glutathione (GSH)-sensitive dithiomaleimide (DTM) to form an amphipathic CS-DTM-CTX (CDC) conjugate, and dasatinib (DAS) co-assembled with the CDC conjugate to obtain DAS@CDC. After CD44 receptor-mediated internalization by CAFs, the nanomedicine could reverse CAFs to normal fibroblasts, blocking their crosstalk with tumor cells and reducing synthesis of major tumor extracellular matrix proteins, including collagen and fibronectin. Meanwhile, the nanomedicine internalized by tumor cells could effectively inhibit tumor proliferation and metastasis, leading to shrinkage of the tumor volume and inhibition of lung metastasis in a subcutaneous 4T1 tumor model with low side effects. Collectively, the nanomedicine showed a remarkably synergistic therapy effect against breast cancer by modulating tumor-stromal crosstalk.

Ultrasmall porphyrin-silica core-shell dots for enhanced fluorescence imaging-guided cancer photodynamic therapy

Clinically used small-molecular photosensitizers (PSs) for photodynamic therapy (PDT) share similar disadvantages, such as the lack of selectivity towards cancer cells, short blood circulation time, life-threatening phototoxicity, and low physiological solubility. To overcome such limitations, the present study capitalizes on the synthesis of ultra-small hydrophilic porphyrin-based silica nanoparticles (core-shell porphyrin-silica dots; PSDs) to enhance the treatment outcomes of cancer via PDT. These ultra-small PSDs, with a hydrodynamic diameter less than 7 nm, have an excellent aqueous solubility in water (porphyrin; TPPS3-NH2) and enhanced tumor accumulation therefore exhibiting enhanced fluorescence imaging-guided PDT in breast cancer cells. Besides ultra-small size, such PSDs also displayed an excellent biocompatibility and negligible dark cytotoxicity in vitro. Moreover, PSDs were also found to be stable in other physiological solutions as a function of time. The fluorescence imaging of porphyrin revealed a prolonged residence time of PSDs in tumor regions, reduced accumulation in vital organs, and rapid renal clearance upon intravenous injection. The in vivo study further revealed reduced tumor growth in 4T1 tumor-bearing bulb mice after laser irradiation explaining the excellent photodynamic therapeutic efficacy of ultra-small PSDs. Thus, ultrasmall hydrophilic PSDs combined with excellent imaging-guided therapeutic abilities and renal clearance behavior represent a promising platform for cancer imaging and therapy.

Insights into stimuli-responsive diselenide bonds utilized in drug delivery systems for cancer therapy

Due to the complexity and particularity of cancer cell microenvironments, redox responsive drug delivery systems (DDSs) for cancer therapy have been extensively explored. Compared with widely reported cancer treatment systems based on disulfide bonds, diselenide bonds have better redox properties and greater anticancer efficiency. In this review, the significance and application of diselenide bonds in DDSs are summarized, and the stimulation sensitivity of diselenide bonds is comprehensively reported. The potential and prospects for the application of diselenide bonds in next-generation anticancer drug treatment systems are extensively discussed.

Self-assembly of a 5-fluorouracil and camptothecin dual drug dipeptide conjugate

Nano-formulated, combinatory therapeutics that control the spatiotemporal aspects of drug release have potential to overcome many of the challenges faced in cancer therapy. Herein, we describe a peptide nanotube functionalized with two anticancer drugs, 5-fluoruracil (5-FU) and camptothecin (CPT). The nanotube was formed via peptide self-assembly, which positioned 5-FU on the surface at the aqueous interface; whereas, CPT was sequestered within the hydrophobic walls. Thus, two different release profiles were observed: rapid release of 5-FU, followed by slower, sustained production of CPT. This profile emerged from the rapid hydrolytic cleavage of 5-FU at the aqueous/nanotube interface, which produced a smaller nanotube comprised of the peptide fragment.

Carrier-free prodrug nanoparticles based on lonidamine and cisplatin for synergistic treatment of breast cancer

Herein, we combined a derivative of cisplatin (CP) and the chemosensitizer lonidamine (LND) to design an amphiphilic prodrug, in which the ratio of LND to cisplatin was fixed at 2:1. Diaminedichlorodihydroxyplatinum (DH-CP) is a hydrophilic cisplatin derivative. Due to its appropriate amphiphilicity, this prodrug could self-assemble into stable nanoparticles (denoted as LNP-NPs). Under the action of excessive glutathione (GSH) in tumor cells, DH-CP could be reduced to cytotoxic cisplatin. In addition, the released LND could inhibit the metabolic process of tumor cells, and improving the sensitivity of tumor cells to cisplatin. In vitro studies demonstrated that LNP-NPs displayed significantly cytotoxicity on breast cancer cells, and the cell viability after co-incubation for 48 h (CP 16 μg/mL) were 18.77% (MCF-7) and 20.01% (EMT6), respectively. LNP-NPs could also significantly inhibit the growth of MCF-7 tumor-like spheroids, which were realized through the high coordination and cooperation between CP and LND. Therefore, the carrier-free drug delivery system based on LND and DH-CP is expected to achieve a good synergistic anti-tumor effect.

Carrier-Free Nanomedicine for Cancer Immunotherapy

With the rapid development of nanotechnology, carrier-based nano-drug delivery systems (DDSs) have been widely studied due to their advantages in optimizing pharmacokinetic and distribution profiles. However, despite those merits, some carrier-related limitations, such as low drug-loading capacity, systematic toxicity and unclear metabolism, usually prevent their further clinical transformation. Carrier-free nanomedicines with non-therapeutic excipients, are considered as an excellent paradigm to overcome these obstacles, owing to their superiority in improving both drug delivery efficacy and safety concern. In recent years, carrier-free nanomedicines have opened new horizons for cancer immunotherapy, and have already made outstanding progress. Herein, in this review, we are focusing on making an integrated and exhaustive overview of lately reports about them. Firstly, the major synthetic strategies of carrier-free nanomedicines are introduced, such as nanocrystals, prodrug-, amphiphilic drug-drug conjugates (ADDCs)-, polymer-drug conjugates-, and peptide-drug conjugates (PepDCs)-assembled nanomedicines. Afterwards, the typical applications of carrier-free nanomedicines in cancer immunotherapy are well-discussed, including cancer vaccines, cytokine therapy, enhancing T-cell checkpoint inhibition, as well as modulating tumor microenvironment (TME). After that, both the advantages and the potential challenges, as well as the future prospects of carrier-free nanomedicines in cancer immunotherapy, were discussed. And we believe that it would be of great potential practiced and reference value to the relative fields.

Fabrication of pH/Redox Dual-Responsive Mixed Polyprodrug Micelles for Improving Cancer Chemotherapy

In this work, we prepared pH/redox dual-responsive mixed polyprodrug micelles (MPPMs), which were co-assembled from two polyprodrugs, namely, poly(ethylene glycol) methyl ether-b-poly (β-amino esters) conjugated with doxorubicin (DOX) via redox-sensitive disulfide bonds (mPEG-b-PAE-ss-DOX) and poly(ethylene glycol) methyl ether-b-poly (β-amino esters) conjugated with DOX via pH-sensitive cis-aconityl bonds (mPEG-b-PAE-cis-DOX) for effective anticancer drug delivery with enhanced therapeutic efficacy. The particle size of MPPMs was about 125 nm with low polydispersity index, indicating the reasonable size and uniform dispersion. The particle size, zeta-potential, and critical micelle concentration (CMC) of MPPMs at different mass ratios of the two kinds of polyprodrugs were dependent on pH value and glutathione (GSH) level, suggesting the pH and redox responsiveness. The drug release profiles in vitro of MPPMs at different conditions were further studied, showing the pH—and redox-triggered drug release mechanism. Confocal microscopy study demonstrated that MPPMs can effectively deliver doxorubicin molecules into MDA-MB-231 cells. Cytotoxicity assay in vitro proved that MPPMs possessed high toxic effect against tumor cells including A549 and MDA-MB-231. The results of in vivo experiments demonstrated that MPPMs were able to effectively inhibit the tumor growth with reduced side effect, leading to enhanced survival rate of tumor-bearing mice. Taken together, these findings revealed that this pH/redox dual-responsive MPPMs could be a potential nanomedicine for cancer chemotherapy. Furthermore, it could be a straightforward way to fabricate the multifunctional system basing on single stimuli-responsive polyprodrugs.

Complementing Cancer Photodynamic Therapy with Ferroptosis through Iron Oxide Loaded Porphyrin-Grafted Lipid Nanoparticles

Nanomaterials that combine multimodality imaging and therapeutic functions within a single nanoplatform have drawn extensive attention for molecular medicines and biological applications. Herein, we report a theranostic nanoplatform based on a relatively smaller (<20 nm) iron oxide loaded porphyrin-grafted lipid nanoparticles (Fe₃O₄@PGL NPs). The amphiphilic PGL easily self-assembled on the hydrophobic exterior surface of ultrasmall Fe₃O₄ NPs, resulting in a final ultrasmall Fe₃O₄@PGL NPs with diameter of ∼10 nm. The excellent self-assembling nature of the as-synthesized PGL NPs facilitated a higher loading of porphyrins, showed a negligible dark toxicity, and demonstrated an excellent photodynamic effect against HT-29 cancer cells in vitro. The in vivo experimental results further confirmed that Fe₃O₄@PGL NPs were ideally qualified for both the fluorescence and magnetic resonance (MR) imaging guided nanoplatforms to track the biodistribution and therapeutic responses of NPs as well as to simultaneously trigger the generation of highly cytotoxic reactive oxygen species (ROS) necessary for excellent photodynamic therapy (PDT). After recording convincing therapeutic responses, we further evaluated the ability of Fe₃O₄@PGL NPs/Fe₃O₄@Lipid NPs for ferroptosis therapy (FT) via tumor microenvironment (TME) modulation for improved anticancer activity. We hypothesized that tumor-associated macrophages (TAMs) could significantly improve the efficacy of FT by accelerating the Fenton reaction in vitro. In our results, the Fe ions released in vitro directly contributed to the Fenton reaction, whereas the presence of RAW 264.7 macrophages further accelerated the ROS generation as observed by the fluorescence imaging. The significant increase in the ROS during the coincubation of NPs, endocytosed by HT-29 cells and RAW264.7 cells, further induced increased cellular toxicity of cancer cells.

Smart-Polypeptide-Coated Mesoporous Fe3O4 Nanoparticles: Non-Interventional Target-Embolization/Thermal Ablation and Multimodal Imaging Combination Theranostics for Solid Tumors

Tumor theranostics hold great potential for personalized medicine in the future, and transcatheter arterial embolization (TAE) is an important clinical treatment for unresectable or hypervascular tumors. In order to break the limitation, simplify the procedure of TAE, and achieve ideal combinatorial theranostic capability, here, a kind of triblock-polypeptide-coated perfluoropentane-loaded mesoporous Fe₃O₄ nanocomposites (PFP-m-Fe₃O₄@PGTTCs) were prepared for non-interventional target-embolization, magnetic hyperthermia, and multimodal imaging combination theranostics of solid tumors. The results of systematic animal experiments by H22-tumor-bearing mice and VX2-tumor-bearing rabbits in vivo indicated that PFP-m-Fe₃O₄@PGTTC-6.3 has specific tumor accumulation and embolization effects. The tumors' growth has been inhibited and the tumors disappeared 4 weeks and ≤15 days post-injection with embolization and magnetic hyperthermia combination therapy, respectively. The results also showed an excellent effect of magnetic resonance/ultrasound/SPECT multimodal imaging. This pH-responsive non-interventional embolization combinatorial theranostics system provides a novel embolization and multifunctional theranostic candidate for solid tumors.

Reversing tumor multidrug resistance with a catalytically active covalent organic framework

We report here a catalytically active nano covalent organic framework [COF(Fe)] with high drug loading capacity for reversing tumor multidrug resistance (MDR). The Fe catalytic sites in COF(Fe) could convert intracellular overexpressed H₂O₂ into highly reactive ˙OH to induce oxidation stress and down-regulate MDR protein. Therefore, COF(Fe) could enhance the intracellular drug accumulation to overcome MDR, which was demonstrated both in vitro and in vivo.

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

The antitumor efficiency and clinical translation of traditional nanomedicines is mainly restricted by low drug loading, complex preparation technology, and potential toxicity caused by the overused carrier materials. In recent decades, small-molecule prodrug nanoassemblies (SMP-NAs), which are formed by the self-assembly of prodrugs themselves, have been widely investigated with distinct advantages of ultrahigh drug-loading and negligible excipients-trigged adverse reaction. Benefited from the simple preparation process, SMP-NAs are widely used for chemotherapy, phototherapy, immunotherapy, and tumor diagnosis. In addition, combination therapy based on the accurate co-delivery behavior of SMP-NAs can effectively address the challenges of tumor heterogeneity and multidrug resistance. Recent trends in SMP-NAs are outlined, and the corresponding self-assembly mechanisms are discussed in detail. Besides, the smart stimuli-responsive SMP-NAs and the combination therapy based on SMP-NAs are summarized, with special emphasis on the structure-function relationships. Finally, the outlooks and potential challenges of SMP-NAs in cancer therapy are highlighted.

Dimeric artesunate-choline conjugate micelles coated with hyaluronic acid as a stable, safe and potent alternative anti-malarial injection of artesunate

Artesunate (ARS) is the only artemisinin-based intravenous drug approved for treatment of malaria in the clinic. ARS is rapidly metabolized in vivo to short lived (∼30-45 min) but fast acting, dihydroartemisinin (DHA). The short half-life of DHA necessitates multiple dose administration to circumvent the risk of recrudescence and development of artemisinin resistance. In this work, we report a stable, safe and potent alternative artemisinin-based injectable nanocomplex consisting of dimeric artesunate-choline conjugate (dACC) micelles coated with hyaluronic acid (HA). Firstly, dACC was synthesized by one-step esterification of two artesunate molecules with 3-(dimethylamino)-1,2-propanediol followed by quaternization. After that, dACC was self-assembled into cationic nanomicelles and further coated with anionic small molecular weight HA. The HA-coated dACC nanocomplex (dACC/HA nanocomplex) has a narrow size distribution of about 30 nm. Hemolytic toxicity and cytotoxicity studies revealed a favorable bio-safety profile. Finally, in vitro and in vivo studies showed the dACC/HA nanocomplex possess superior safety and antimalarial efficacy compared to ARS. Taken together, the dACC/HA nanocomplex is a promising injectable alternative to the traditional clinically used artesunate.

Enhancing Cancer Immunotherapeutic Efficacy with Sonotheranostic Strategies

Immunotherapy has revolutionized the modality for establishing a firm immune response and immunological memory. However, intrinsic limitations of conventional low responsive poor T cell infiltration and immune related adverse effects urge the coupling of cancer nanomedicines with immunotherapy for boosting antitumor response under ultrasound (US) sensitization to mimic dose-limiting toxicities for safe and effective therapy against advanced cancer. US is composed of high-frequency sound waves that mediate targeted spatiotemporal control over release and internalization of the drug. The unconventional US triggered immunogenic nanoengineered arena assists the limited immunogenic dose, limiting toxicities and efficacies. In this Review, we discuss current prospects of enhanced immunotherapy using nanomedicine under US. We highlight how nanotechnology designs and incorporates nanomedicines for the reprogramming of systematic immunity in the tumor microenvironment. We also emphasize the mechanical and biological potential of US, encompassing sonosensitizer activation for enhanced immunotherapeutic efficacies. Finally, the smartly converging combinational platform of US stimulated cancer nanomedicines for amending immunotherapy is summarized. This Review will widen scientists' ability to explore and understand the limiting factors for combating cancer in a precisely customized way.

Reduction-Sensitive Dextran-Paclitaxel Polymer-Drug Conjugate: Synthesis, Self-Assembly into Nanoparticles, and In Vitro Anticancer Efficacy

Delivery systems that can encapsulate a precise amount of drug and offer a spatiotemporally controlled drug release are being actively sought for safe yet effective cancer therapy. Compared to polymer nanoparticle (NP)-based delivery systems that rely on physical drug encapsulation, NPs derived from stimuli-sensitive covalent polymer-drug conjugates (PDCs) have emerged as promising alternatives offering precise control over drug dosage and spatiotemporal drug release. Herein, we report a reduction-sensitive PDC "Dex-SS-PTXL" synthesized by conjugating dextran and paclitaxel (PTXL) through a disulfide bond-bearing linker. The synthesized Dex-SS-PTXL PDC with a precise degree of substitution in terms of the percentage of repeat units of dextran covalently conjugated to PTXL (27 ± 0.6%) and the amount of drug carried by the PDC (39 ± 1.4 wt %) was found to self-assemble into spherical NPs with an average size of 110 ± 34 nm and a ζ-potential of -14.09 ± 8 mV. The reduction-sensitive Dex-SS-PTXL NPs were found to release PTXL exclusively in response to the reducing agent concentration reflective of the intracellular reducing environment of the tumor cells. Challenging BT-549 and MCF-7 cells with Dex-SS-PTXL NPs revealed significant cytotoxicity, while the IC₅₀ values and the mode of action (mitotic arrest) of Dex-SS-PTXL NPs were found to be comparable to those of free PTXL, highlighting the active nature of the intracellularly released drug. The developed PDC with its unique ability to self-assemble into NPs and stimuli-responsive drug release can enhance the success of the NP-based drug delivery systems during clinical translation.

Carrier-free prodrug nanoparticles based on dasatinib and cisplatin for efficient antitumor in vivo

Carrier-free drug self-delivery systems consisting of amphiphilic drug-drug conjugate (ADDC) with well-defined structure and nanoscale features have drawn much attention in tumor drug delivery. Herein, we report a simple and effective strategy to prepare ADDC using derivatives of cisplatin (CP) and dasatinib (DAS), which further self-assembled to form reduction-responsive nanoparticles (CP-DDA NPs). DAS was modified with succinic anhydride and then connected with CP derivative by ester bonds. The size, micromorphology and in vitro drug release of CP-DDA NPs were characterized. The biocompatibility and bioactivity of these carrier-free nanoparticles were then investigated by HepG2 cells and H22-tumor bearing mice. In vitro and in vivo experiments proved that CP-DDA NPs had excellent anti-tumor activity and significantly reduced toxicities. This study provides a new strategy to design the carrier-free nanomedicine composed of CP and DAS for synergistic tumor treatment.

Self-assembled ternary hybrid nanodrugs for overcoming tumor resistance and metastasis

Traditional chemotherapy exhibits a certain therapeutic effect toward malignant cancer, but easily induce tumor multidrug resistance (MDR), thereby resulting in the progress of tumor recurrence or metastasis. In this work, we deigned ternary hybrid nanodrugs (PEI/DOX@CXB-NPs) to simultaneously combat against tumor MDR and metastasis. In vitro results demonstrate this hybrid nanodrugs could efficiently increase cellular uptake at pH 6.8 by the charge reversal, break lysosomal sequestration by the proton sponge effect and trigger drugs release by intracellular GSH, eventually leading to higher drugs accumulation and cell-killing in drug-sensitive/resistant cells. In vivo evaluation revealed that this nanodrugs could significantly inhibit MDR tumor growth and simultaneously prevent A549 tumor liver/lung metastasis owing to the specifically drugs accumulation. Mechanism studies further verified that hybrid nanodrugs were capable of down-regulating the expression of MDR or metastasis-associated proteins, lead to the enhanced anti-MDR and anti-metastasis effect. As a result, the multiple combination strategy provided an option for effective cancer treatment, which could be potentially extended to other therapeutic agents or further use in clinical test.

Natural bioactive molecules: An alternative approach to the treatment and control of glioblastoma multiforme

Glioblastoma multiforme is one of the most deadly malignant tumors, with more than 10,000 cases recorded annually in the United States. Various clinical analyses and studies show that certain chronic diseases, including cancer, interact between cell-reactive radicals rise and pathogenesis. Reactive oxygen and nitrogenous sources include endogenous (physiological processes), and exogenous sources contain reactive oxygen and nitrogen (xenobiotic interaction). The cellular oxidation/reduction shifts to oxidative stress when the regulation mechanisms of antioxidants are surpassed, and this raises the ability to damage cellular lipids, proteins, and nucleic acids. OBJECTIVE: This review is focused on how phytochemicals play crucial role against glioblastoma multiforme and to combat these, bioactive molecules and their derivatives are either used alone, in combination with anticancer drugs or as nanomedicine formulations for better cancer theranostics over the conventional approach. CONCLUSION: Bioactive molecules found in seeds, vegetables, and fruits have antioxidant, anti-inflammatory, and anticancer properties that may help cancer survivors feel better throughout chemotherapy or treatment. However, incorporating them into the nanocarrier-based drug delivery for the treatment of GBMs, which could be a promising therapeutic strategy for this tumor entity, increasing targeting effectiveness, increasing bioavailability, and reducing side effects with this target-specificity, drug internalization into cells is significantly improved, and off-target organ aggregation is reduced.

Prospects of Delivering Natural Compounds by Polymer-Drug Conjugates in Cancer Therapeutics

Synthetic chemotherapeutics have played a crucial role in minimizing mostly palliative symptoms associated with cancer; however, they have also created other problems such as system toxicity due to a lack of specificity. This has led to the development of polymer-drug conjugates amongst other novel drug delivery systems. Most of the formulations designed using delivery systems consist of synthetic drugs and face issues such as drug resistance, which has already rendered drugs such as antibiotics ineffective. This is further exacerbated by toxicity due to long term use. Given these problems and the fact that conjugation of synthetic compounds to polymers has been relatively slow with no formulation on the market after a decade of extensive studies, the focus has shifted to using this platform with medicinal plant extracts to improve solubility, specificity and increase drug release of medicinal and herbal bioactives. In recent years, various plant extracts such as flavonoids, tannins and terpenoids have been studied extensively using this approach. The success of formulations developed using novel drug-delivery systems is highly dependent on the tumour microenvironment especially on the enhanced permeability and retention effect. As a result, the compromised lymphatic network and 'leaky' vasculature exhibited by tumour cells act as a guiding principle in the delivering of these formulations. This review focuses on the state of the polymer-drug conjugates and their exploration with natural compounds, the progress and difficulties thus far, and future directions concerning cancer treatment.

Cannabidiol-dihydroartemisinin conjugates for ameliorating neuroinflammation with reduced cytotoxicity

Cannabidiol (CBD) and dihydroartemisinin (DHA) can alleviate neuroinflammatory responses. However, they show cytotoxicity, which severely limits their therapeutic windows. Therefore, there is a great need to develop neuroprotective agents with improved safety. Drug-drug conjugate is an emerging approach for enhancing therapeutic index. Herein, the development, synthesis, and the pharmacological characterization of CBD-DHA conjugates were performed. Meanwhile, the combination of CBD and DHA as separate entities was also quantitatively analyzed for direct comparison with CBD-DHA conjugates. In this study, BV-2 microglial cell line was used to mimic primary microglia and the effects of CBD, DHA, the combination of CBD and DHA, as well as CBD-DHA conjugates on LPS-activated signaling molecules and pro-inflammatory factors were assessed. The interaction of CBD and DHA in inhibiting LPS-induced nitric oxide (NO) production was found to be additive. In contrast, DHA was found to synergize with CBD in inhibiting BV-2 cellular viability which implies that the combination of CBD and DHA amplifies their cytotoxicity. CBD-DHA conjugate C3D eliminated the cytotoxicity associated with single CBD/DHA use without significantly compromising the anti-neuroinflammation activity. C3D was more potent than C2D and C4D in inhibiting LPS-induced NO and mRNAs of iNOS and IL-1β, which implies that the linker length is critical for CBD-DHA conjugates' anti-inflammatory activities. Further signaling characterizations showed that C3D inhibited LPS-induced NF-κB but not MAPKs activation in BV-2 cells, therefore blocking LPS-induced neuroinflammation. This work provides a good example that conjugated drug-drug approach may improve the therapeutic index by increasing the maximum tolerated concentration/dose compared to traditional combination strategy.

Cyanine conjugates in cancer theranostics

Cyanine is a meritorious fluorogenic core for the construction of fluorescent probes and its phototherapeutic potential has been enthusiastically explored as well. Alternatively, the covalent conjugation of cyanine with other potent therapeutic agents not only boosts its therapeutic efficacy but also broadens its therapeutic modality. Herein, we summarize miscellaneous cyanine-therapeutic agent conjugates in cancer theranostics from literature published between 2014 and 2020. The application scenarios of such theranostic cyanine conjugates covered common cancer therapeutic modalities, including chemotherapy, phototherapy and targeted therapy. Besides, cyanine conjugates that serve as nanocarriers for drug delivery are introduced as well. In an additional section, we analyze the potential of these conjugates for clinical translation. Overall, this review is aimed to stimulate research interest in exploring unattempted therapeutic agents and novel conjugation strategies and hopefully, accelerate clinical translation in this field.

Photosensitizer Nanoparticles Boost Photodynamic Therapy for Pancreatic Cancer Treatment

Patients with pancreatic cancer (PCa) have a poor prognosis apart from the few suitable for surgery. Photodynamic therapy (PDT) is a minimally invasive treatment modality whose efficacy and safety in treating unresectable localized PCa have been corroborated in clinic. Yet, it suffers from certain limitations during clinical exploitation, including insufficient photosensitizers (PSs) delivery, tumor-oxygenation dependency, and treatment escape of aggressive tumors. To overcome these obstacles, an increasing number of researchers are currently on a quest to develop photosensitizer nanoparticles (NPs) by the use of a variety of nanocarrier systems to improve cellular uptake and biodistribution of photosensitizers. Encapsulation of PSs with NPs endows them significantly higher accumulation within PCa tumors due to the increased solubility and stability in blood circulation. A number of approaches have been explored to produce NPs co-delivering multi-agents affording PDT-based synergistic therapies for improved response rates and durability of response after treatment. This review provides an overview of available data regarding the design, methodology, and oncological outcome of the innovative NPs-based PDT of PCa.

Key considerations in designing CRISPR/Cas9-carrying nanoparticles for therapeutic genome editing

CRISPR-Cas9, the breakthrough genome-editing technology, has emerged as a promising tool to prevent and cure various diseases. The efficient genome editing technology strongly relies on the specific and effective delivery of CRISPR/Cas9 cargos. However, the lack of a safe, specific, and efficient non-viral delivery system for in vivo genome editing remains a major limit for its clinical translation. In this review, we will first briefly introduce the working mechanism of CRISPR/Cas9 and the patterns of CRISPR/Cas9 delivery. Furthermore, the physiological obstacles for the delivery process in vivo are elaborated. Finally, the key considerations will be deeply discussed in designing non-viral nanovectors for therapeutic CRISPR/Cas9 delivery in vivo, including the effective encapsulation of large-size macromolecules, targeting specific tissues and cells, efficient endosomal escape and safety concerns of the vector systems, in the hope of inviting more comprehensive studies on the development of safe, specific, and efficient non-viral nanovectors for delivering a CRISPR/Cas9 system.

Carrier-free nanodrugs for safe and effective cancer treatment

Clinical applications of many anti-cancer drugs are restricted due to their hydrophobic nature, requiring use of harmful organic solvents for administration, and poor selectivity and pharmacokinetics resulting in off-target toxicity and inefficient therapies. A wide variety of carrier-based nanoparticles have been developed to tackle these issues, but such strategies often fail to encapsulate drug efficiently and require significant amounts of inorganic and/or organic nanocarriers which may cause toxicity problems in the long term. Preparation of nano-formulations for the delivery of water insoluble drugs without using carriers is thus desired, requiring elegantly designed strategies for products with high quality, stability and performance. These strategies include simple self-assembly or involving chemical modifications via coupling drugs together or conjugating them with various functional molecules such as lipids, carbohydrates and photosensitizers. During nanodrugs synthesis, insertion of redox-responsive linkers and tumor targeting ligands endows them with additional characteristics like on-target delivery, and conjugation with immunotherapeutic reagents enhances immune response alongside therapeutic efficacy. This review aims to summarize the methods of making carrier-free nanodrugs from hydrophobic drug molecules, evaluating their performance, and discussing the advantages, challenges, and future development of these strategies.

New Insights Into Targeting Membrane Lipids for Cancer Therapy

Modulation of membrane lipid composition and organization is currently developing as an effective therapeutic strategy against a wide range of diseases, including cancer. This field, known as membrane-lipid therapy, has risen from new discoveries on the complex organization of lipids and between lipids and proteins in the plasma membranes. Membrane microdomains present in the membrane of all eukaryotic cells, known as lipid rafts, have been recognized as an important concentrating platform for protein receptors involved in the regulation of intracellular signaling, apoptosis, redox balance and immune response. The difference in lipid composition between the cellular membranes of healthy cells and tumor cells allows for the development of novel therapies based on targeting membrane lipids in cancer cells to increase sensitivity to chemotherapeutic agents and consequently defeat multidrug resistance. In the current manuscript strategies based on influencing cholesterol/sphingolipids content will be presented together with innovative ones, more focused in changing biophysical properties of the membrane bilayer without affecting the composition of its constituents.

Kinetic stability-driven cytotoxicity of small-molecule prodrug nanoassemblies

Nanoassemblies (NAs) of small-molecule lipophilic prodrugs have been widely investigated for efficient drug delivery in cancer therapy, but their kinetic stability has not attracted sufficient attention in the past studies. Herein, we reported that kinetic stability has a great influence on the drug release from the NAs of lipophilic prodrugs in physiologically relevant media. Based on the co-assembled FRET nanosystems of two lipophilic fluorescent prodrugs, we demonstrated that NAs constructed by lipophilic prodrugs containing shorter alkyl chains or those with higher unsaturated degrees displayed poorer kinetic stability, which further resulted in remarkably faster drug release in mouse plasma and various tissue homogenates. More importantly, these kinetically unstable NAs also induced rapid intracellular drug release, resulting in much more potent cytotoxicity. These findings highlight the crucial role of kinetic stability in determining the drug release from the NAs of lipophilic prodrugs, which would effectively guide their rational designs for cancer therapy.

Dimeric prodrug-based nanomedicines for cancer therapy

With the rapid development of conjugation chemistry and biomedical nanotechnology, prodrug-based nanosystems (PNS) have emerged as promising drug delivery nanoplatforms. Dimeric prodrug, as an emerging branch of prodrug, has been widely investigated by covalently conjugating two same or different drug molecules. In recent years, great progress has been made in dimeric prodrug-based nanosystems (DPNS) for cancer therapy. Many advantages offered by DPNS have significantly facilitated the delivery efficiency of anticancer drugs, such as high drug loading capacity, favorable pharmacokinetics, tumor stimuli-sensitive drug release and facile combination theranostics. Given the rapid developments in this field, we here outline the latest updates of DPNS in cancer treatment, focusing on dimeric prodrug-encapsulated nanosystems, dimeric prodrug-nanoassemblies and tumor stimuli-responsive DPNS. Moreover, the design principle, advantages and challenges of DPNS for clinical cancer therapy are also highlighted.

Evaluation of a GSH-targeting prodrug via a sulfonamide-induced "integrative" platform for selective cancer therapy

A sulfonamide-appended gemcitabine prodrug was newly produced. The prodrug was shown to efficiently distinguish GSH from cysteine and homocysteine. Upon reaction of this prodrug with GSH, which is relatively abundant in tumor cells, sulfonyl group cleavage occurred as well as active release of the drug GMC and a concomitant increase in the innate fluorescence intensity. As a proof of concept, colocalization experiments were carried out; these experiments demonstrated that the probe LHX resulted in, via receptor-mediated endocytosis, significantly improved therapeutic efficacy and few side effects. Thus, these results indicated the theranostic agent to be a promising "integrative" platform for efficient cancer therapy. The agent can be activated in real time, and not only be selectively monitored and localized by specific tumour cells, but also undergo cascaded cleavage to induce both a fluorogenic response and release of an active cytotoxic drug.

Targeted Prodrug-Based Self-Assembled Nanoparticles for Cancer Therapy

Background

Targeted prodrug has various applications as drug formulation for tumor therapy. Therefore, amphoteric small-molecule prodrug combined with nanoscale characteristics for the self-assembly of the nano-drug delivery system (DDS) is a highly interesting research topic.

Methods and Results

In this study, we developed a prodrug self-assembled nanoplatform, 2-glucosamine-fluorescein-5(6)-isothiocyanate-glutamic acid-paclitaxel (2DA-FITC-PTX NPs) by integration of targeted small molecule and nano-DDS with regular structure and perfect targeting ability. 2-glucosamine (DA) and paclitaxel were conjugated as the targeted ligand and anti-tumor chemotherapy drug by amino acid group. 2-DA molecular structure can enhance the targeting ability of prodrug-based 2DA-FITC-PTX NPs and prolong retention time, thereby reducing the toxicity of normal cell/tissue. The fluorescent dye FITC or near-infrared fluorescent dye ICG in prodrug-based DDS was attractive for in vivo optical imaging to study the behavior of 2DA-FITC-PTX NPs. In vitro and in vivo results proved that 2DA-FITC-PTX NPs exhibited excellent targeting ability, anticancer activity, and weak side effects.

Conclusion

This work demonstrates a new combination of nanomaterials for chemotherapy and may promote prodrug-based DDS clinical applications in the future.

Fibronectin-targeted dual-acting micelles for combination therapy of metastatic breast cancer

Stage IV breast cancer, which has a high risk of invasion, often develops into metastases in distant organs, especially in the lung, and this could threaten the lives of women. Thus, the development of more advanced therapeutics that can efficiently target metastatic foci is crucial. In this study, we built an dual-acting therapeutic strategy using micelles with high stability functionalized with fibronectin-targeting CREKA peptides encapsulating two slightly soluble chemotherapy agents in water, doxorubicin (D) and vinorelbine (V), which we termed C-DVM. We found that small C-DVM micelles could efficiently codeliver drugs into 4T1 cells and disrupt microtubule structures. C-DVM also exhibited a powerful ability to eradicate and inhibit invasion of 4T1 cells. Moreover, an in vivo pharmacokinetics study showed that C-DVM increased the drug circulation half-life and led to increased enrichment of drugs in lung metastatic foci after 24 h. Moreover, dual-acting C-DVM treatment led to 90% inhibition of metastatic foci development and reduced invasion of metastases. C-DVM could potentially be used as a targeted treatment for metastasis and represents a new approach with higher therapeutic efficacy than conventional chemotherapy for stage IV breast cancer that could be used in the future.

Glutathione-responsive disassembly of disulfide dicyanine for tumor imaging with reduction in background signal intensity

Near-infrared (NIR) fluorescence imaging has been proved as an effective modality in identifying the tumor border and distinguishing the tumor cells from healthy tissue during the oncological surgery. Developing NIR fluorescent probes with high tumor to background (T/B) signal is essential for the complete debulking of the tumor, which will prolong the survival rate of tumor patients. However, the nonspecific binding and "always-on" properties of the conventional fluorescent probes leads to high background signals and poor specificity. Method: To address this problem, glutathione (GSH)-responsive, two disulfide-bonded dicyanine dyes (ss-diCy5 and ss-diNH800CW) were synthesized. As synthesized dyes are quenched under normal physiological conditions, however, once reached to the tumor site, these dyes are capable of emitting strong fluorescence signals primarily because of the cleavage of the disulfide bond in the tumor microenvironment with high GSH concentration. Besides, the GSH-responsive behavior of these dyes was monitored using the UV-vis and fluorescence spectroscopy. The diagnostic accuracy of the aforementioned dyes was also tested both in tumor cells and 4T1-bearing mice. Results: The fluorescence signal intensity of disulfide dicyanine dyes was quenched up to 89% compared to the mono cyanine dyes, thus providing a very low fluorescence background. However, when the disulfide dicyanine dye reaches the tumor site, the dicyanine is cleaved by GSH into two mono-dyes with high fluorescence strength, thus producing strong fluorescent signals upon excitation. The fluorescent signal of the dicyanine was enhanced by up to 27-fold after interacting with the GSH solution. In vivo xenografts tumor studies further revealed that the fluorescence signals of aforementioned dyes can be quickly recovered in the solid tumor. Conclusion: In summary, the disulfide dicyanines dyes can provide a promising platform for specific tumor-activatable fluorescence imaging with improved T/B value.

Synergistically Enhanced Inhibitory Effects of Pullulan Nanoparticle-Mediated Co-Delivery of Lovastatin and Doxorubicin to Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) is a subtype of breast cancer that is prone to drug resistance and difficult to treat. In this study, we grafted water-soluble pullulan with lovastatin (LV) to develop a novel amphiphilic conjugate, pullulan-encapsulated LV (PLV). The PLV conjugate was synthesized with three different ratios of pullulan to LV and characterized by Fourier transform infrared (FTIR). The degree of substitution (DS) of LV in terms of molar ratio was 7.87%, 3.58%, and 3.06% for PLV (1/2), PLV (1/3), and PLV (1/4), respectively, by proton NMR analysis. We selected the PLV (1/2) conjugate to prepare doxorubicin (DXR)-loaded PLV nanoparticles (PLV/DXR NPs) because of its superior properties. The average size and zeta potential for PLV (1/2) NPs were 177.6 nm and - 11.66 mV, respectively, determined by dynamic light scattering, and those for PLV/DXR NPs were 225.6 nm and - 10.51 mV, respectively. In vitro drug release profiling showed that PLV/DXR NPs sustainably released DXR within 72 h, which was more robust at pH 5.4 (97.90%) than pH 7.4 (76.15%). In the cytotoxicity study, PLV/DXR NPs showed greater inhibition of proliferation of TNBC MDA-MB-231 than non-TNBC MDA-MB-453 cells (IC₅₀ 0.60 vs 11.05 μM). FITC-loaded PLV/DXR NPs were prepared to investigate cellular uptake: both cell lines showed a time-dependent uptake of NPs, but the number of NPs entering MDA-MB-231 cells was greater than that entering the MDA-MB-453 cells. Pullulan-based NP co-delivery of LV and DXR could efficiently inhibit TNBC cells, which may help in designing a powerful drug delivery system for treating TNBC.

Manganese(iii)-chelated porphyrin microbubbles for enhanced ultrasound/MR bimodal tumor imaging through ultrasound-mediated micro-to-nano conversion

Manganese(iii)-chelated porphyrin microbubbles (MnP-MBs) were fabricated by self-assembly from a Mn-chelated porphyrin lipid followed by encapsulating perfluoropropane-an inert gas. The obtained MnP-MBs exhibited enhanced ultrasound imaging ability after intravenous injection. Under the guidance of ultrasound imaging, MnP-MBs could be converted into nanoparticles in situ with local tumor ultrasound disruption, achieving rapid tumor MRI contrast enhancement within 30 min at a very low Mn injection dose of 0.09 mg (1.65 μmol) per kg.

Porphyrin-Based Nanomedicines for Cancer Treatment

As unique molecules with both therapeutic and diagnostic properties, porphyrin derivatives have been extensively employed for cancer treatment. Porphyrins not only show powerful phototherapeutic effects (photodynamic and photothermal therapies), but also exhibit excellent imaging capacities, such as near-infrared fluorescent imaging (NIRFI), magnetic resonance imaging (MRI), photoacoustic imaging (PAI), positron emission tomography (PET), and single-photon emission computed tomography (SPECT). In order to take advantage of their robust phototherapeutic effects and excellent imaging capacities, porphyrins can be used to create nanomedicines with effective therapeutic and precise diagnostic properties for cancer treatment. In this Review, we summarize porphyrin-based nanomedicines which have been developed recently, including porphyrin-based liposomes, micelles, polymeric nanoparticles, peptide nanoparticles, and small-molecule nanoassemblies, and their applications on cancer therapy and diagnosis. The outlook and limitation of porphyrin-based nanomedicines are also reviewed.