A Near-Infrared Laser-Triggered Size-Shrinkable Nanosystem with In Situ Drug Release for Deep Tumor Penetration

The application of bacteria-nanomaterial hybrids in antitumor therapy

Adverse effects and multidrug resistance remain significant obstacles in conventional cancer therapy. Nanomedicines, with their intrinsic properties such as nano-sized dimensions and tunable surface characteristics, have the potential to mitigate the side effects of traditional cancer treatments. While nanomaterials have been widely applied in cancer treatment, challenges such as low targeting efficiency and poor tumor penetration persist. Recent research has shown that anaerobic bacteria exhibit high selectivity for primary tumors and metastatic cancers, offering good safety and superior tumor penetration capabilities. This suggests that combining nanomaterials with bacteria could complement their respective limitations, opening vast potential applications in cancer therapy. The use of bacteria in combination with nanomaterials for anticancer treatments, including chemotherapy, radiotherapy, and photothermal/photodynamic therapy, has contributed to the rapid development of the field of bacterial oncology treatments. This review explores the mechanisms of bacterial tumor targeting and summarizes strategies for synthesizing bacterial-nanomaterial and their application in cancer therapy. The combination of bacterial-nanomaterial hybrids with modern therapeutic approaches represents a promising avenue for future cancer treatment research, with the potential to improve treatment outcomes for cancer patients.

Near-infrared Light-Triggered Size-Shrinkable theranostic nanomicelles for effective tumor targeting and regression

Most nanomedicines with suitable sizes (normally 100-200 nm) exhibit favorable accumulation in the periphery of tumors but hardly penetrate into deep tumors. Effective penetration of nanomedicines requires smaller sizes (less than 30 nm) to overcome the elevated tumor interstitial fluid pressure. Moreover, integrating an efficient diagnostic agent in the nanomedicines is in high demand for precision theranostics of tumors. To this end, a near-infrared light (NIR) -triggered size-shrinkable micelle system (Fe3O4@AuNFs/DOX-M) coloaded antitumor drug doxorubicin (DOX) and biomodal imaging agent magnetic gold nanoflower (Fe3O4@AuNFs) was developed to achieve efficient theranostic of tumors. Upon the accumulation of Fe3O4@AuNFs/DOX-M in the tumor periphery, a NIR laser was irradiated near the tumor sites, and the loaded Fe3O4@Au NFs could convert the light energy to heat, which triggered the cleavage of DOX-M to the ultra-small micelles (∼5 nm), thus realizing the deep penetration of micelles and on-demand drug release. Moreover, Fe3O4@AuNFs in the micelles could also be used as CT/MRI dual-modal contrast agent to "visualize" the tumor. Up to 92.6 % of tumor inhibition was achieved for the developed Fe3O4@AuNFs/DOX-M under NIR irradiation. This versatile micelle system provided a promising drug carrier platform realizing efficient tumor dual-modal diagnosis and photothermal-chemotherapy integration.

Size Switchable Self-Assembled Iron Oxide Aggregations Loaded with Doxorubicin for Deep Penetration and Enhanced Chemotherapy of Cancer

Iron oxide nanoparticles (Fe3O4 NPs) have been reported to be a promising agent for cancer therapy due to their outstanding ability in catalyzing the Fenton reaction and causing peroxidation. Generally, particles with size of hundreds of nanometers exhibit enhanced accumulation in tumor due to the enhanced permeation and retention effect. However, the large size hinders penetration within the dense collagen matrix. Here, we propose a multistage system to realize pH-responsive size switch for efficient drug delivery. In this system, ultrasmall Fe3O4 (∼4 nm) NPs are simultaneously modified with hydrophilic mPEG and hydrophobic N,N-dibutylethylenediamine (DBE) to form pH-responsive self-assembled iron oxide aggregations (SIOA). In the acidic tumor microenvironment, the protonation of DBE makes it transit from the hydrophobic to hydrophilic state, causing the disassembly of the SIOA and the release of loaded doxorubicin. The multistage Fe3O4 NPs demonstrate enhanced accumulation and efficient diffusion within the tumor, holding a promise for drug delivery and cancer therapy.

Material and Design Toolkit for Drug Delivery: State of the Art, Trends, and Challenges

The nanomaterial and related toolkit have promising applications for improving human health and well-being. Nanobased drug delivery systems use nanoscale materials as carriers to deliver therapeutic agents in a targeted and controlled manner, and they have shown potential to address issues associated with conventional drug delivery systems. They offer benefits for treating various illnesses by encapsulating or conjugating biological agents, chemotherapeutic drugs, and immunotherapeutic agents. The potential applications of this technology are vast; however, significant challenges exist to overcome such as safety issues, toxicity, efficacy, and insufficient capacity. This article discusses the latest developments in drug delivery systems, including drug release mechanisms, material toolkits, related design molecules, and parameters. The concluding section examines the limitations and provides insights into future possibilities.

Synergistic Approaches in the Design and Applications of UCST Polymers

This review summarizes recent progress in the synergistic design strategy for thermoresponsive polymers possessing an upper critical solution temperature (UCST) in aqueous systems. To achieve precise control of the responsive behavior of the UCST polymers, their molecular design can benefit from a synergistic effect of hydrogen bonding with other interactions or modification of the chemical structures. The combination of UCST behavior with other stimuli-responsive properties of the polymers may yield new functional materials with potential applications such as sensors, actuators, and controlled release devices. The advances in this area provide insight or inspiration into the understanding and design of functional UCST polymers for a wide range of applications.

Escherichia coli Nissle 1917-driven microrobots for effective tumor targeted drug delivery and tumor regression

Potent tumor regression remains challenging due to the lack of effective targeted drug delivery into deep tumors as well as the reduced susceptibility of cancer cells to anticancer agents in hypoxic environments. Bacteria-driven drug-delivery systems are promising carriers in overcoming targeting and diffusion limits that are inaccessible for conventional antitumor drugs. In this study, probiotic facultative anaerobe Escherichia coli Nissle 1917 (EcN) was functionalized and formed self-propelled microrobots to actively deliver therapeutic drug and photosensitizer to the deep hypoxic regions of tumors. Doxorubicin (Dox) was firstly modified with cis-aconityl anhydride (CA) and terminal thiol-decorated hydrazone derivative (Hyd-SH) through dual pH-sensitive amide and imine bonds, respectively. The functionalized CA-Dox-Hyd-SH was further coordinated with photosensitizer gold nanorods (AuNRs) and then conjugated to the surface of EcN. The resulting microrobots (EcN-Dox-Au) inherited the mobility characteristics and bioactivity of native EcN. Upon the irradiation of NIR laser, the microrobots exhibited enhanced tumor accumulation and penetration into the deep hypoxia tumor site. Strikingly, after 21 days of treatment with EcN-Dox-Au formulations, complete tumor regression was achieved without relapse for at least 53 days. This self-propelled strategy utilizing bacteria-driven microrobots provides a promising paradigm for enhancing drug penetration and elevating chemosensitivity, resulting in a superior antitumor effect. STATEMENT OF SIGNIFICANCE: Self-propelled Escherichia coli Nissle 1917 (EcN) - mediated microrobots are functionalized to co-deliver therapeutic drugs and photosensitizers to the deep tumor site. Anti-tumor drug doxorubicin (Dox) was modified through dual pH-sensitive bonds on both terminals and then linked with EcN and photosensitizer gold nanorods (AuNRs) to realize tumor microenvironment acidic pH-responsive drug release. Upon irradiation with a NIR laser near the tumor site, AuNRs produced a photothermal effect which realized the superficial tumor thermal ablation and increased the permeability of the tumor cell membrane to facilitate the penetration of microrobots. Moreover, the deep penetration of microrobots also enhanced the susceptibility of the cancer cells to Dox, and realized the complete tumor regression in the established breast cancer-bearing mice without recurrence using a lower dose of drug regimen.

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.

Flexible bioelectronic innovation for personalized health management

With the vigorous development of intelligent medical care and interdisciplinary science, innovative flexible bioelectronics (FBEs) are emerging in health monitoring, disease diagnosis and treatment, and even cancer therapy. This work comments on the recent progress of FBEs in personalized health management, emphasizing its innovative role in cancer therapy. Future perspectives on the challenges and opportunities for the next-generation innovative FBEs are also proposed.

Transformable nanodrugs for overcoming the biological barriers in the tumor environment during drug delivery

Drug delivery systems have been studied massively with explosive growth in the last few decades. However, challenges such as biological barriers are still obstructing the delivery efficiency of nanomedicines. Reports have shown that the physicochemical properties, such as the morphologies of nanodrugs, could highly affect their biodistribution and bioavailability. Therefore, transformable nanodrugs that take advantage of different sizes and shapes allow for overcoming multiple biological barriers, providing promising prospects for drug delivery. This review aims to present an overview of the most recent developments of transformable nanodrugs in this emerging field. First, the design principles and transformation mechanisms which serve as guidelines for smart nanodrugs are summarized. Afterward, their applications in overcoming biological barriers, including the bloodstream, intratumoral pressure, cellular membrane, endosomal wrapping, and nuclear membrane, are highlighted. Finally, discussions on the current developments and future perspectives of transformable nanodrugs are given.

Folate modified dual pH/reduction-responsive mixed micelles assembled using FA-PEG-PDEAEMA and PEG-SS-PCL for doxorubicin delivery

Aiming at achieving the concurrent performances of high loading, well controlled release and active targeted delivery, folate (FA) modified dual pH/reduction-responsive mixed polymeric micelles were rationally assembled using FA-PEG-PDEAEMA and PEG-SS-PCL by dissipative particle dynamics (DPD) simulations. The optimized polymers PEG₁₁₂-PDEAEMA₄₀, FA-PEG₁₁₂-PDEAEMA₄₀, and PEG₁₁₂-SS-PCL₇₀ were synthesized and characterized using ¹H NMR, FT-IR and GPC, and their mixed micelles were applied for doxorubicin (DOX) delivery. The drug loading capacity (LC) and encapsulation efficiency (EE) values of the MIX1 (FA-PEG₁₁₂-PDEAEMA₄₀/PEG₁₁₂-SS-PCL₇₀) at a DOX/polymer feeding ratio of 15 mg/30 mg were 20.22% and 50.69%, which were higher than those of single polymer micelles and MIX2 (PEG₁₁₂-PDEAEMA₄₀/PEG₁₁₂-SS-PCL₇₀). Particle size distributions, mesoscopic morphologies, DPD simulations and in vitro drug release profiles all confirmed the well-controlled release performance of the DOX-loaded micelles formed by MIX1: slow DOX release with a cumulative release of 20.46% in the neutral environment and accelerated release with a cumulative release of 74.20% at pH 5.0 + 10 mM DTT within 120 h, which were similar to those of MIX2. Cytotoxicity assay found that both MIX1 and MIX2 blank micelles were biocompatible, and a superior inhibitory effect of the FA-modified DOX-loaded micelles MIX1 on HepG2 cells was found compared to that of free DOX and non-FA-modified DOX-loaded micelles MIX2. All of these confirmed the superiority of MIX1 micelles with high loading capacity, well controlled release, and enhanced inhibitory effects on HepG2 cells, which might be a prospective candidate for anticancer drug delivery.

Gold nanorods-loaded chitosan-based nanomedicine platform enabling an effective tumor regression in vivo

The clinical utility of 7-ethyl-10-hydroxycamptothecin (SN-38) is hampered by its low water solubility and reduced bioactivity at neutral or alkaline conditions. The rational design of an effective drug delivery system that can significantly enhance the therapeutic index of SN-38 and achieve complete tumor regression still remains a challenge. Herein, chitosan-based hybrid nanoparticles system co-loading with chemotherapeutic drug SN-38 and gold nanorods (AuNRs) was engineered for effective combinational photothermal-chemotherapy. To increase the solubility of SN-38, soluble polymeric prodrug poly (l-glutamic acid)-SN38 (l-PGA-SN38) was firstly synthesized and then complexed with chitosan to form stable nanomedicine via a mild and facile way without using any organic solvent or surfactant. Upon introducing AuNRs into chitosan-based nanomedicine by coordination interaction between the amine group of chitosan and AuNRs, the hybrid nanoparticles exhibited distinct synergistic therapeutic effect compared with single chemotherapy or photothermal treatment in vitro and in vivo. Almost complete tumor regression was achieved after 21-day treatment of the developed hybrid nanoparticles and showed no recurrence for at least 60 days.

Bacterial outer membrane vesicles-based therapeutic platform eradicates triple-negative breast tumor by combinational photodynamic/chemo-/immunotherapy

Bacterial outer membrane vesicles (OMVs) are potent immuno-stimulating agents and have the potentials to be bioengineered as platforms for antitumor nanomedicine. In this study, OMVs are demonstrated as promising antitumor therapeutics. OMVs can lead to beneficial M2-to-M1 polarization of macrophages and induce pyroptosis to enhance antitumor immunity, but the therapeutic window of OMVs is narrow for its toxicity. We propose a bioengineering strategy to enhance the tumor-targeting ability of OMVs by macrophage-mediated delivery and improve the antitumor efficacy by co-loading of photosensitizer chlorin e6 (Ce6) and chemotherapeutic drug doxorubicin (DOX) into OMVs as a therapeutic platform. We demonstrate that systemic injection of the DOX/Ce6-OMVs@M therapeutic platform, providing combinational photodynamic/chemo-/immunotherapy, eradicates triple-negative breast tumors in mice without side effects. Importantly, this strategy also effectively prevents tumor metastasis to the lung. This OMVs-based strategy with bioengineering may serve as a powerful therapeutic platform for a synergic antitumor therapy.

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Bacterial outer membrane vesicles (OMVs) are bioengineered for combinational tumor photodynamic/chemo-/immunotherapy.

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The therapeutic platform eradicates the tumor and prevents lung metastasis in mice with improved safety.

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OMVs showed antitumor immunity by inducing M2-to-M1 polarization of macrophages and pyroptosis of tumor cells.

Advancements in redox-sensitive micelles as nanotheranostics: A new horizon in cancer management

World Health Organisation (WHO) delineated cancer as one of the foremost reasons for mortality with 10 million deaths in the year 2020. Early diagnosis and effective drug delivery are of utmost importance in cancer management. The entrapment of both bio-imaging dyes and drugs will open novel avenues in the area of tumor theranostics. Elevated levels of reactive oxygen species (ROS) and glutathione (GSH) are the characteristic features of the tumor microenvironment (TME). Researchers have taken advantage of these specific TME features in recent years to develop micelle-based theranostic nanosystems. This review focuses on the advantages of redox-sensitive micelles (RSMs) and supramolecular self-assemblies for tumor theranostics. Key chemical linkers employed for the tumor-specific release of the cargo have been discussed. In vitro characterisation techniques used for the characterization of RSMs have been deliberated. Potential bottlenecks that may present themselves in the bench-to-bedside translation of this technology and the regulatory considerations have been deliberated.

Next-generation engineered nanogold for multimodal cancer therapy and imaging: a clinical perspectives

Cancer is one of the significant threats to human life. Although various latest technologies are currently available to treat cancer, it still accounts for millions of death each year worldwide. Thus, creating a need for more developed and novel technologies to combat this deadly condition. Nanoparticles-based cancer therapeutics have offered a promising approach to treat cancer effectively while minimizing adverse events. Among various nanoparticles, nanogold (AuNPs) are biocompatible and have proved their efficiency in treating cancer because they can reach tumors via enhanced permeability and retention effect. The size and shape of the AuNPs are responsible for their diverse therapeutic behavior. Thus, to modulate their therapeutic values, the AuNPs can be synthesized in various shapes, such as spheres, cages, flowers, shells, prisms, rods, clusters, etc. Also, attaching AuNPs with single or multiple targeting agents can facilitate the active targeting of AuNPs to the tumor tissue. The AuNPs have been much explored for photothermal therapy (PTT) to treat cancer. In addition to PTT, AuNPs-based nanoplatforms have been investigated for combinational multimodal therapies in the last few years, including photodynamic therapy, chemotherapy, radiotherapy, immunotherapy, etc., to ablate cancer cells. Thus, the present review focuses on the recent advancements in the functionalization of AuNPs-based nanoconstructs for cancer imaging and therapy using combinatorial multimodal approaches to treat various cancers.

Gold-Polymer Nanocomposites for Future Therapeutic and Tissue Engineering Applications

Gold nanoparticles (AuNPs) have been extensively investigated for their use in various biomedical applications. Owing to their biocompatibility, simple surface modifications, and electrical and unique optical properties, AuNPs are considered promising nanomaterials for use in in vitro disease diagnosis, in vivo imaging, drug delivery, and tissue engineering applications. The functionality of AuNPs may be further expanded by producing hybrid nanocomposites with polymers that provide additional functions, responsiveness, and improved biocompatibility. Polymers may deliver large quantities of drugs or genes in therapeutic applications. A polymer alters the surface charges of AuNPs to improve or modulate cellular uptake efficiency and their biodistribution in the body. Furthermore, designing the functionality of nanocomposites to respond to an endo- or exogenous stimulus, such as pH, enzymes, or light, may facilitate the development of novel therapeutic applications. In this review, we focus on the recent progress in the use of AuNPs and Au-polymer nanocomposites in therapeutic applications such as drug or gene delivery, photothermal therapy, and tissue engineering.

Emerging strategies based on nanomaterials for ionizing radiation-optimized drug treatment of cancer

Drug-radiotherapy is a common and effective combinational treatment for cancer. This study aimed to explore the ionizing radiation-optimized drug treatment based on nanomaterials so as to improve the synergistic efficacy of drug-radiotherapy against cancer and limit the adverse effect on healthy organs. In this review, these emerging strategies were divided into four parts. First, the delivery of the drug-loaded nanoparticles was optimized owing to the strengthened passive targeting process, active targeting process, and cell targeting process of nanoparticles after ionizing radiation exposure. Second, nanomaterials were designed to respond to the ionizing radiation, thus leading to the release of the loading drugs controllably. Third, radiation-activated pro-drugs were loaded onto nanoparticles for radiation-triggered drug therapy. In particular, nontoxic nanoparticles with radiosensitization capability and innocuous radio-dynamic contrast agents can be considered as radiation-activated drugs, which were discussed in this review. Fourth, according to the various synergetic mechanisms, radiotherapy could improve the drug response of cancer, obtaining optimized drug-radiotherapy. Finally, relative suggestions were provided to further optimize these aforementioned strategies. Therefore, a novel topic was selected and the emerging strategies in this region were discussed, aiming to stimulate the inspiration for the development of ionizing radiation-optimized drug treatment based on nanomaterials.