Recent advances and applications of nitroreductase activable agents for tumor theranostic

Nitroreductase activable agents offer a personalized and targeted approach to cancer theranostics by selectively activating prodrugs within the tumor microenvironment. These agents enable non-invasive tumor imaging, image-guided drug delivery, and real-time treatment monitoring. By leveraging the enzymatic action of tumor-specific nitroreductase enzymes, cytotoxic drugs are delivered directly to cancer cells while minimizing systemic toxicity. This review highlights the key features, mechanisms of action, diagnostic applications, therapeutic potentials, and future directions of nitroreductase activable agents for tumor theranostics. Integration with imaging modalities, advanced drug delivery systems, immunotherapy combinations, and theranostic biomarkers shows promise for optimizing treatment outcomes and improving patient survival in oncology. Continued research and innovation in this field are crucial for advancing novel theranostic strategies and enhancing patient care. Nitroreductase activable agents represent a promising avenue for personalized cancer therapy and have the potential to transform cancer diagnosis and treatment approaches.

[12]aneN3-modified camptothecin and PEGylated AIEgens co-assembly into core-shell nanoparticles with ROS/NTR dual-response for enhanced cancer therapy

A novel dual-responsive nanoparticle (NP) system was aimed to be developed for the co-delivery of camptothecin (CPT) and plasmid encoding TNF-related apoptosis-inducing ligand (pTRAIL) DNA in cancer therapy. The combination of the prodrug CPT and the nucleic acid condensing di-(triazole-[12]aneN3) unit with 4-nitrobenzyl ester through alkyl chains resulted in three nitroreductase (NTR) responsive amphiphiles, CNN1-CNN3 (with 5, 8, and 11 carbon chains, respectively). Among them, CNN2 was the most effective in inhibiting the proliferation of HeLa cells in the presence of fusogenic lipid DOPE. The NPs composed of CNN2, pDNA, and DOPE were further co-assembled with ROS-responsive thioketal-linked amphiphilic polymer (TTP) to afford the core-shell NPs (CNN2-DT/pDNA) with an average size of 118 nm, which exhibited high drug-loading capacity, excellent serum tolerance, and good biocompatibility. In the presence of ROS, NTR, and NADH, the core-shell NPs were decomposed, leading to the efficient release of 80% CPT and abundant pDNA. The self-assembly and delivery process of CNN2-DT NPs and DNA were clearly observed through the AIE fluorescent imaging. In vitro and in vivo results demonstrated that the CNN2-DT/pTRAIL NPs synergistically promoted 68% apoptosis of tumor cells and inhibited tumor growth with negligible toxic side effects. This study showed that the combination of prodrug and nucleic acid through dual-responsive core-shell NPs provide a spatially and temporally-controlled strategy for cancer therapy.

Responsive shape-shifting nanoarchitectonics and its application in tumor diagnosis and therapy

Nanodrug delivery system has a great application in the treatment of solid tumors by virtue of EPR effect, though its success in clinics is still limited by its poor extravasation, small intratumoral accumulation, and weak tumor penetration. The shape of nanoparticles (NPs) greatly affects their circulation time, flow behavior, intratumoral amassing, cell internalization as well as tumor tissue penetration. Generally, short nanorods and 100-200 nm spherical nanocarriers possess nice circulation behaviors, nanorods and nanofibers with a large aspect ratio (AR) cumulate well at tumor sites, and tiny nanospheres/disks (< 50 nm) and short nanorods with a low AR achieve a favorable tumor tissue penetration. The AR and surface evenness of NPs also tune their cell contact, cell ingestion, and drug accumulation at tumor sites. Therefore, adopting stimulus-responsive shape-switching (namely, shape-shifting nanoarchitectonics) can not only ensure a good circulation and extravasation for NPs, but also and more importantly, promote their amassing, retention, and penetration in tumor tissues to maximize therapeutic efficacy. Here we review the recently developed shape-switching nanoarchitectonics of antitumoral NPs based on stimulus-responsiveness, demonstrate how successful they are in tumor shrinking and elimination, and provide new ideas for the optimization of anticancer nanotherapeutics.

Mucus-penetrating nonviral gene vaccine processed in the epithelium for inducing advanced vaginal mucosal immune responses

Establishment of vaginal immune defenses at the mucosal interface layer through gene vaccines promise to prevent infectious diseases among females. Mucosal barriers composed of a flowing mucus hydrogel and tightly conjugated epithelial cells (ECs), which represent the main technical difficulties for vaccine development, reside in the harsh, acidic human vaginal environment. Different from frequently employed viral vectors, two types of nonviral nanocarriers were designed to concurrently overcome the barriers and induce immune responses. Differing design concepts include the charge-reversal property (DRLS) to mimic a virus that uses any cells as factories, as well as the addition of a hyaluronic acid coating (HA/RLS) to directly target dendritic cells (DCs). With a suitable size and electrostatic neutrality, these two nanoparticles penetrate a mucus hydrogel with similar diffusivity. The DRLS system expressed a higher level of the carried human papillomavirus type 16 L1 gene compared to HA/RLS in vivo. Therefore it induced more robust mucosal, cellular, and humoral immune responses. Moreover, the DLRS applied to intravaginal immunization induced high IgA levels compared with intramuscularly injected DNA (naked), indicating timely protection against pathogens at the mucus layer. These findings also offer important approaches for the design and fabrication of nonviral gene vaccines in other mucosal systems.

Stimuli-Responsive Aggregation-Induced Emission (AIE)-Active Polymers for Biomedical Applications

At high concentration or in the aggregated state, most of the traditional luminophores suffer from the general aggregation-caused quenching (ACQ) effect, which significantly limits their biomedical applications. On the contrary, a few fluorophores exhibit an aggregation-induced emission (AIE) feature which is just the opposite of ACQ. The luminophores with aggregation-induced emission (AIEgens) have exhibited noteworthy advantages to get tunable emission, excellent photostability, and biocompatibility. Incorporating AIEgens into polymer design has yielded diversified polymer systems with fascinating photophysical characteristics. Again, stimuli-responsive polymers are capable of undergoing chemical and/or physical property changes on receiving signals from single or multiple stimuli. The combination of the AIE property and stimuli responses in a single polymer platform provides a feasible and effective strategy for the development of smart polymers with promising biomedical applications. Herein, the advancements in stimuli-responsive polymers with AIE characteristics for biomedical applications are summarized. AIE-active polymers are first categorized into conventional π-π conjugated and nonconventional fluorophore systems and then subdivided based on various stimuli, such as pH, redox, enzyme, reactive oxygen species (ROS), and temperature. In each section, the design strategies of the smart polymers and their biomedical applications, including bioimaging, cancer theranostics, gene delivery, and antimicrobial examples, are introduced. The current challenges and future perspectives of this field are also stated at the end of this review article.

Macromolecular conjugated cyanine fluorophore nanoparticles for tumor-responsive photo nanotheranostics

For photothermal therapy (PTT), the improved targeting can decrease the dosage and promote the therapeutic function of photothermal agents, which would effectively improve the antitumor effect. The tumor microenvironment (TME) and cells are targets in designing intelligent and responsive theranostics. However, most of these schemes have been limited to the traditional visible and first near-infrared (NIR-I) regions, eager to expand to the second near-infrared (NIR-II) window. We designed and synthesized a polyethylene glycol conjugated and disulfide-modified macromolecule fluorophore (MPSS). MPSS could self-assemble into core-shell micelles in an aqueous solution (MPSS-NPS), while the small molecule probes were in a high aggregation arrangement inside the nanoparticle. The pronounced aggregation quenching (ACQ) effect caused them to the "sleeping" state. After entering the tumor cells, the disulfide bonds in MPSS-NPS broke in response to a high concentration of glutathione (GSH) in TME, and the molecule probes were released. The highly aggregated state was effectively alleviated, resulting in distinct absorption enhancement in the near-infrared region. Therefore, the fluorescence signal was recovered, and the photothermal performance was triggered. In vitro and in vivo studies reveal that the Nano-system is efficient for the smart NIR-II fluorescence imaging-guided PTT, even at a low dosage and density of irradiation.

Small molecule based fluorescent chemosensors for imaging the microenvironment within specific cellular regions

The microenvironment (local environment), including viscosity, temperature, polarity, hypoxia, and acidic-basic status (pH), plays indispensable roles in cellular processes. Significantly, organelles require an appropriate microenvironment to perform their specific physiological functions, and disruption of the microenvironmental homeostasis could lead to malfunctions of organelles, resulting in disorder and disease development. Consequently, monitoring the microenvironment within specific organelles is vital to understand organelle-related physiopathology. Over the past few years, many fluorescent probes have been developed to help reveal variations in the microenvironment within specific cellular regions. Given that a comprehensive understanding of the microenvironment in a particular cellular region is of great significance for further exploration of life events, a thorough summary of this topic is urgently required. However, there has not been a comprehensive and critical review published recently on small-molecule fluorescent chemosensors for the cellular microenvironment. With this review, we summarize the recent progress since 2015 towards small-molecule based fluorescent probes for imaging the microenvironment within specific cellular regions, including the mitochondria, lysosomes, lipid drops, endoplasmic reticulum, golgi, nucleus, cytoplasmic matrix and cell membrane. Further classifications at the suborganelle level, according to detection of microenvironmental factors by probes, including polarity, viscosity, temperature, pH and hypoxia, are presented. Notably, in each category, design principles, chemical synthesis, recognition mechanism, fluorescent signals, and bio-imaging applications are summarized and compared. In addition, the limitations of the current microenvironment-sensitive probes are analyzed and the prospects for future developments are outlined. In a nutshell, this review comprehensively summarizes and highlights recent progress towards small molecule based fluorescent probes for sensing and imaging the microenvironment within specific cellular regions since 2015. We anticipate that this summary will facilitate a deeper understanding of the topic and encourage research directed towards the development of probes for the detection of cellular microenvironments.

Gemini Lipopeptide Bearing an Ultrashort Peptide for Enhanced Transfection Efficiency and Cancer-Cell-Specific Cytotoxicity

Cationic gemini lipopeptides are a relatively new class of amphiphilic compounds to be used for gene delivery. Through the possibility of incorporating short peptides with cell-penetrating functionalities, these lipopeptides may be advantageous over traditional cationic lipids. Herein, we report the design, synthesis, and application of a novel cationic gemini lipopeptide for gene delivery. An ultrashort peptide, containing four amino acids, arginine-cysteine-cysteine-arginine, serves as a cationic head group, and two α-tocopherol moieties act as hydrophobic anchoring groups. The new lipopeptide (ATTA) is incorporated into the conventional liposomes, containing 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and 1,2-dioleoyl-sn-glycerol-3-phosphoethanolamine (DOPE), at different molar ratios. The formulated liposomes are characterized and screened for better transfection efficiency. Transfection activity in multiple human cell lines from cancerous and noncancerous origins indicates that the inclusion of an optimal ratio of ATTA in the liposomes substantially enhances the transfection efficiency, superior to that of a traditional liposome, DOTAP-DOPE. Cytotoxicity of ATTA-containing formulations against multiple cell lines indicates potentially distinct activity between cancer and noncancer cell lines. Furthermore, lipoplexes of the ATTA-containing formulations with anticancer therapeutic gene, plasmid encoding tumor necrosis factor-related apoptosis-inducing ligand (pTRAIL), induce obviously more cytotoxicity than conventional formulations. The results indicate that arginine-rich cationic lipopeptide appears to be a promising ingredient in gene delivery vector formulations to enhance transfection efficiency and cell-selective cytotoxicity.

Delivery of siHIF-1α to Reconstruct Tumor Normoxic Microenvironment for Effective Chemotherapeutic and Photodynamic Anticancer Treatments

The tumor hypoxic microenvironment not only induces genetic and epigenetic changes in tumor cells, immature vessels formation for oxygen demand, but also compromises the efficiency of therapeutic interventions. On the other hand, conventional therapeutic approaches which kill tumor cells or destroy tumor blood vessels to block nutrition and oxygen supply usually facilitate even harsher microenvironment. Thus, simultaneously relieving the strained response of tumor cells and blood vessels represents a promising strategy to reverse the adverse tumor hypoxic microenvironment. In the present study, an integrated amphiphilic system (RSCD) is designed based on Angiotensin II receptor blocker candesartan for siRNA delivery against the hypoxia-inducible factor-1 alpha (HIF-1α), aiming at both vascular and cellular "relaxation" to reconstruct a tumor normoxic microenvironment. Both in vitro and in vivo studies have confirmed that the hypoxia-inducible HIF-1α expression is down-regulated by 70% and vascular growth is inhibited by 60%. The "relaxation" therapy enables neovascularization with more complete and organized structures to obviously increase the oxygen level inside tumor, which results in a 50% growth inhibition. Moreover, reconstruction of tumor microenvironment enhances tumor-targeted drug delivery, and significantly improves the chemotherapeutic and photodynamic anticancer treatments.

Polymeric nano-carriers for on-demand delivery of genes via specific responses to stimuli

Polymeric nano-carriers have been developed as a most capable and feasible technology platform for gene therapy. As vehicles, polymeric nano-carriers are obliged to possess high gene loading capability, low immunogenicity, safety, and the ability to transfer various genetic materials into specific sites of target cells to express therapeutic proteins or block a process of gene expression. To this end, various types of polymeric nano-carriers have been prepared to release genes in response to stimuli such as pH, redox, enzymes, light and temperature. These stimulus-responsive nano-carriers exhibit high gene transfection efficiency and low cytotoxicity. In particular, dual- and multi-stimulus-responsive polymeric nano-carriers can respond to a combination of signals. Markedly, these combined responses take place either simultaneously or in a sequential manner. These dual-stimulus-responsive polymeric nano-carriers can control gene delivery with high gene transfection both in vitro and in vivo. In this review paper, we highlight the recent exciting developments in stimulus-responsive polymeric nano-carriers for gene delivery applications.

Nitroreductase-responsive polymeric micelles based on 4-nitrobenzyl and AIE moieties for intracellular doxorubicin release

An amphiphilic polymer TNP demonstrated the formation of a nitroreductase-responsive DOX delivery nanoplatform with high sensitivity and selectivity.

A parallel and cascade control system: magnetofection of miR125b for synergistic tumor-association macrophage polarization regulation and tumor cell suppression in breast cancer treatment

Polarization regulation of tumor-association macrophages (TAMs) is a promising treatment method for tumors, but aiming at TAMs alone shows unsatisfactory therapeutic efficiency. Therefore, we designed a parallel and cascade control system for both macrophage polarization and tumor cell inhibition. The system is composed of cationic lipopeptides with an arginine-rich periphery (RLS) and anionic magnetic nanoparticles (MNPs) for fleet transfection of miR-125b. Based on the highly efficient magnetofection, miR-125b successfully shows a parallel effect on both M1, promoting polarization by targeting interferon regulatory factor 4 (IRF4) in macrophages, and tumor cell inhibition, by targeting ETS proto-oncogene 1 and cyclin- J. The cascading effect on M1-associated genes is upregulated by up to two orders of magnitude, while M2-associated genes are downregulated. Meanwhile, MNPs also have an effect on the TAM polarization and 4T1 tumor cell inhibition via inflammatory related gene expression and Fenton reaction. Further mimicking the co-culture of RAW264.7 and 4T1 cells in vitro confirmed the synergistic therapy effect. In the treatment of orthotopic breast cancer in mice, considerable M1 macrophage polarization was observed in the RM125b treated group, showing distinct tumor-suppressive effects, with a tumor weight reduction of 60% and tumor metastasis suppression of 50%.

Cascaded bio-responsive delivery of eNOS gene and ZNF580 gene to collaboratively treat hindlimb ischemia via pro-angiogenesis and anti-inflammation

The cascaded, bio-responsively delivered eNOS gene and ZNF₅₈₀ gene overcome transfection bottlenecks and collaboratively exert anti-ischemic function via promoting angiogenesis and alleviating inflammation.