O-carboxymethyl chitosan based pH/hypoxia-responsive micelles relieve hypoxia and induce ROS in tumor microenvironment

Recent progress in stimuli-responsive polymeric micelles for targeted delivery of functional nanoparticles

Stimuli-responsive polymeric micelles have emerged as a revolutionary approach for enhancing the in vivo stability, biocompatibility, and targeted delivery of functional nanoparticles (FNPs) in biomedicine. This article comprehensively reviews the preparation methods of these polymer micelles, detailing the innovative strategies employed to introduce stimulus responsiveness and surface modifications essential for precise targeting. We delve into the breakthroughs in utilizing these micelles to selectively deliver various FNPs including magnetic nanoparticles, upconversion nanoparticles, gold nanoparticles, and quantum dots, highlighting their transformative impact in the biomedical realm. Concluding, we present an insight into the current research landscape, addressing the challenges at hand, and envisioning the future trajectory in this burgeoning domain. Join us as we navigate the exciting confluence of polymer science and nanotechnology in reshaping biomedical solutions.

O-carboxymethyl chitosan in biomedicine: A review

O-carboxymethyl chitosan (O-CMC) is a chitosan derivative produced through the substitution of hydroxyl (-OH) functional groups in glucosamine units with carboxymethyl (-CH2COOH) substituents, effectively addressing the inherent solubility issues of chitosan in aqueous solutions. O-CMC has garnered significant interest due to its enhanced solubility, elevated viscosity, minimal toxicity, and advantageous biocompatibility properties. Furthermore, O-CMC demonstrates antibacterial, antifungal, and antioxidant characteristics, rendering it a promising candidate for various biomedical uses such as wound healing, tissue engineering, anti-tumor therapies, biosensors, and bioimaging. Additionally, O-CMC is well-suited for the fabrication of nanoparticles, hydrogels, films, microcapsules, and tablets, offering opportunities for effective drug delivery systems. This review outlines the distinctive features of O-CMC, offers analyses of advancements and future potential based on current research, examines significant obstacles for clinical implementation, and foresees its ongoing significant impacts in the realm of biomedicine.

Hyaluronic acid/dextran-based polymeric micelles co-delivering ursolic acid and doxorubicin to mitochondria for potentiating chemotherapy in MDR cancer

Cancer multidrug resistance (MDR) dramatically hindered the efficiency of standard chemotherapy. Mitochondria are highly involved in the occurrence and development of MDR; thus, inducing its malfunction will be an appealing strategy to treat MDR tumors. In this paper, a natural polysaccharides-based nanoplatform (TDTD@UA/HA micelles) with cell and mitochondria dual-targeting ability was facilely fabricated to co-deliver ursolic acid (UA) and doxorubicin (DOX) for combinatorial MDR therapy. TDTD@UA/HA micelles featured a spherical morphology, narrow size distribution (∼140 nm), as well as favorable drug co-loading capacity (DOX: 8.41 %, UA: 9.06 %). After hyaluronic acid (HA)-mediated endocytosis, the lysosomal hyaluronidase promoted the degradation of HA layer and then the positive triphenylphosphine groups were exposed, which significantly enhanced the mitochondria-accumulation of nano micelles. Subsequently, DOX and UA were specifically released into mitochondria under the trigger of endogenous reactive oxygen species (ROS), followed by severe mitochondrial destruction through generating ROS, exhausting mitochondrial membrane potential, and blocking energy supply, etc.; ultimately contributing to the susceptibility restoration of MCF-7/ADR cells to chemotherapeutic agents. Importantly, TDTD@UA/HA micelles performed potent anticancer efficacy without distinct toxicity on the MDR tumor-bearing nude mice model. Overall, the versatile nanomedicine represented a new therapeutic paradigm and held great promise in overcoming MDR-related cancer.

pH-Responsive Amphiphilic Triblock Fluoropolymers as Assemble Oxygen Nanoshuttles for Enhancing PDT against Hypoxic Tumor

Photodynamic therapy (PDT) is a cancer treatment strategy that utilizes photosensitizers to convert oxygen within tumors into reactive singlet oxygen (1O2) to lyse tumor cells. Nevertheless, pre-existing tumor hypoxia and oxygen consumption during PDT can lead to an insufficient oxygen supply, potentially reducing the photodynamic efficacy. In response to this issue, we have devised a pH-responsive amphiphilic triblock fluorinated polymer (PDP) using copper-mediated RDRP. This polymer, composed of poly(ethylene glycol) methyl ether acrylate, 2-(diethylamino)ethyl methacrylate, and (perfluorooctyl)ethyl acrylate, self-assembles in an aqueous environment. Oxygen, chlorine e6 (Ce6), and doxorubicin (DOX) can be codelivered efficiently by PDP. The incorporation of perfluorocarbon into the formulation enhances the oxygen-carrying capacity of PDP, consequently extending the lifetime of 1O2. This increased lifetime, in turn, amplifies the PDT effect and escalates the cellular cytotoxicity. Compared with PDT alone, PDP@Ce6-DOX-O2 NPs demonstrated significant inhibition of tumor growth. This study proposes a novel strategy for enhancing the efficacy of PDT.

Marine biomaterials in biomedical nano/micro-systems

Marine resources in unique marine environments provide abundant, cost-effective natural biomaterials with distinct structures, compositions, and biological activities compared to terrestrial species. These marine-derived raw materials, including polysaccharides, natural protein components, fatty acids, and marine minerals, etc., have shown great potential in preparing, stabilizing, or modifying multifunctional nano-/micro-systems and are widely applied in drug delivery, theragnostic, tissue engineering, etc. This review provides a comprehensive summary of the most current marine biomaterial-based nano-/micro-systems developed over the past three years, primarily focusing on therapeutic delivery studies and highlighting their potential to cure a variety of diseases. Specifically, we first provided a detailed introduction to the physicochemical characteristics and biological activities of natural marine biocomponents in their raw state. Furthermore, the assembly processes, potential functionalities of each building block, and a thorough evaluation of the pharmacokinetics and pharmacodynamics of advanced marine biomaterial-based systems and their effects on molecular pathophysiological processes were fully elucidated. Finally, a list of unresolved issues and pivotal challenges of marine-derived biomaterials applications, such as standardized distinction of raw materials, long-term biosafety in vivo, the feasibility of scale-up, etc., was presented. This review is expected to serve as a roadmap for fundamental research and facilitate the rational design of marine biomaterials for diverse emerging applications.

Stimuli-responsive probes for amplification-based imaging of miRNAs in living cells

MicroRNAs (miRNAs) have emerged as important biomarkers in biomedicine and bioimaging due to their roles in various physiological and pathological processes. Real-time and in situ monitoring of dynamic fluctuation of miRNAs in living cells is crucial for understanding these processes. However, current miRNA imaging probes still have some limitations, including the lack of effective amplification methods for low abundance miRNAs bioanalysis and uncontrollable activation, leading to background signals and potential false-positive results. Therefore, researchers have been integrating activatable devices with miRNA amplification techniques to design stimuli-responsive nanoprobes for "on-demand" and precise imaging of miRNAs in living cells. In this review, we summarize recent advances of stimuli-responsive probes for the amplification-based imaging of miRNAs in living cells and discuss the future challenges and opportunities in this field, aiming to provide valuable insights for accurate disease diagnosis and monitoring.

Polysaccharide-based tumor microenvironment-responsive drug delivery systems for cancer therapy

The biochemical indicators of tumor microenvironment (TME) that are different from normal tissues provide the possibility for constructing intelligent drug delivery systems (DDSs). Polysaccharides with good biocompatibility, biodegradability, and unique biological properties are ideal materials for constructing DDSs. Nanogels, micelles, organic-inorganic nanocomposites, hydrogels, and microneedles (MNs) are common polysaccharide-based DDSs. Polysaccharide-based DDSs enable precise control of drug delivery and release processes by incorporating TME-specific biochemical indicators. The classification and design strategies of polysaccharide-based TME-responsive DDSs are comprehensively reviewed. The advantages and challenges of current polysaccharide-based DDSs are summarized and the future directions of development are foreseen. The polysaccharide-based TME-responsive DDSs are expected to provide new strategies and solutions for cancer therapy and make important contributions to the realization of precision medicine.

Construction of multi-program responsive vitamin E succinate-chitosan-histidine nanocarrier and its response strategy in tumor therapy

Multifunctional drug delivery carriers have emerged as a promising cancer drug delivery strategy. Here, we developed a vitamin E succinate-chitosan-histidine (VCH) multi-program responsive drug carrier. The structure was characterized by FT-IR and 1H NMR spectrum, and the DLS and SEM results showed typical nanostructures. The drug loading content was 21.0 % and the corresponding encapsulation efficiency was 66.6 %. The UV-vis and fluorescence spectra demonstrated the existence of the π-π stacking interaction between DOX and VCH. Drug release experiments implied good pH sensitivity and sustained-release effect. The DOX/VCH nanoparticles could be efficiently taken up by HepG2 cancer cells and the tumor inhibition rate was up to 56.27 %. The DOX/VCH reduced the tumor volume and weight efficiently with a TIR of 45.81 %. The histological analysis results showed that DOX/VCH could effectively inhibit tumor growth and proliferation, and there was no damage to normal organs. VCH nanocarriers could combine the advantages of VES, histidine and chitosan to achieve pH sensitivity and P-gp inhibition, and effectively improve the drug solubility, targeting and lysosomal escape. Through the program response of different micro-environment, the newly developed polymeric micelles could successfully be utilized as a multi-program responsive nanocarrier system for the treatment of cancers.

Tumor Therapy Strategies Based on Microenvironment-Specific Responsive Nanomaterials

The tumor microenvironment (TME) is a complex and variable region characterized by hypoxia, low pH, high redox status, overexpression of enzymes, and high-adenosine triphosphate concentrations. In recent years, with the continuous in-depth study of nanomaterials, more and more TME-specific response nanomaterials are used for tumor treatment. However, the complexity of the TME causes different types of responses with various strategies and mechanisms of action. Aiming to systematically demonstrate the recent advances in research on TME-responsive nanomaterials, this work summarizes the characteristics of TME and outlines the strategies of different TME responses. Representative reaction types are illustrated and their merits and demerits are analyzed. Finally, forward-looking views on TME-response strategies for nanomaterials are presented. It is envisaged that such emerging strategies for the treatment of cancer are expected to exhibit dramatic trans-clinical capabilities, demonstrating the extensive potential for the diagnosis and therapy of cancer.

Polysaccharide-Based Stimulus-Responsive Nanomedicines for Combination Cancer Immunotherapy

Cancer immunotherapy is a promising antitumor approach, whereas nontherapeutic side effects, tumor microenvironment (TME) intricacy, and low tumor immunogenicity limit its therapeutic efficacy. In recent years, combination immunotherapy with other therapies has been proven to considerably increase antitumor efficacy. However, achieving codelivery of the drugs to the tumor site remains a major challenge. Stimulus-responsive nanodelivery systems show controlled drug delivery and precise drug release. Polysaccharides, a family of potential biomaterials, are widely used in the development of stimulus-responsive nanomedicines due to their unique physicochemical properties, biocompatibility, and modifiability. Here, the antitumor activity of polysaccharides and several combined immunotherapy strategies (e.g., immunotherapy combined with chemotherapy, photodynamic therapy, or photothermal therapy) are summarized. More importantly, the recent progress of polysaccharide-based stimulus-responsive nanomedicines for combination cancer immunotherapy is discussed, with the focus on construction of nanomedicine, targeted delivery, drug release, and enhanced antitumor effects. Finally, the limitations and application prospects of this new field are discussed.

Combined chemo and photo therapy of programmable prodrug carriers to overcome delivery barriers against nasopharyngeal carcinoma

Indocyanine green (ICG) has been employed in medical diagnostics due to its superior photophysical characteristics. However, these advantages are offset by its quick body clearance and inferior photo-stability. In this work, programmable prodrug carriers for chemotherapy/PDT/PTT against nasopharyngeal carcinoma (NPC) were created in order to increase photo-stability and get around biochemical hurdles. The programmable prodrug carriers (PEG-PLA@DIT-PAMAM) that proactively penetrated deeply into NPC tumors and produced the deep phototherapy and selective drug release under laser irradiation was created by dendrimer-DOX/ICG/TPP (DIT-PAMAM) and PEGylated poly (α-lipoic acid) (PLA) copolymer. Long circulation times and minimal toxicity to mammalian cells are two benefits of PEG-coated carriers. The overexpressed GSH on the tumor cell or vascular endothelial cell of the NPC disintegrated the PEG-g-PLA chains and released the DIT-PAMAM nanoparticles after the carriers had reached the NPC tumor periphery. Small, positively charged DIT-PAMAM nanoparticles may penetrate tumors effectively and remain inside tumor for an extended period of time. In addition, the induced ROS cleaved the thioketal linkers for both DOX and nanoparticles and product hyperthermia (PTT) to kill cancer cells under laser irradiation, facilitating faster diffusion of nanoparticles and more effective tumor penetration with a programmable publication of DOX. The programmable prodrug carries showed high photo-stability high photo-stability, which enabled very effective PDT, PTT, and tumor-specific DOX release. With the goal of combining the effects of chemotherapy, PDT, and PTT against NPC, this research showed the great efficacy of programmable prodrug carriers.

Manipulate tumor hypoxia for improved photodynamic therapy using nanomaterials

Due to its low adverse effects, minimal invasiveness, and outstanding patient compliance, photodynamic therapy (PDT) has drawn a great deal of interest, which is achieved through incomplete reduction of O₂ by a photosensitizer under light illumination that produces amounts of reactive oxygen species (ROS). However, tumor hypoxia significantly hinders the therapeutic effect of PDT so that tumor cells cannot be eliminated, which results in tumor cells proliferating, invading, and metastasizing. Additionally, O₂ consumption during PDT exacerbates hypoxia in tumors, leading to several adverse events after PDT treatment. In recent years, various investigations have focused on conquering or using tumor hypoxia by nanomaterials to amplify PDT efficacy, which is summarized in this review. This comprehensive review's objective is to present novel viewpoints on the advancement of oxygenation nanomaterials in this promising field, which is motivated by hypoxia-associated anti-tumor therapy.

Hydrogel systems for targeted cancer therapy

When hydrogel materials with excellent biocompatibility and biodegradability are used as excellent new drug carriers in the treatment of cancer, they confer the following three advantages. First, hydrogel materials can be used as a precise and controlled drug release systems, which can continuously and sequentially release chemotherapeutic drugs, radionuclides, immunosuppressants, hyperthermia agents, phototherapy agents and other substances and are widely used in the treatment of cancer through radiotherapy, chemotherapy, immunotherapy, hyperthermia, photodynamic therapy and photothermal therapy. Second, hydrogel materials have multiple sizes and multiple delivery routes, which can be targeted to different locations and types of cancer. This greatly improves the targeting of drugs, thereby reducing the dose of drugs and improving treatment effectiveness. Finally, hydrogel can intelligently respond to environmental changes according to internal and external environmental stimuli so that anti-cancer active substances can be remotely controlled and released on demand. Combining the abovementioned advantages, hydrogel materials have transformed into a hit in the field of cancer treatment, bringing hope to further increase the survival rate and quality of life of patients with cancer.