Effect of Cationic Charge Density on Transcytosis of Polyethylenimine

Developing bioinspired delivery systems for enhanced tumor penetration of macromolecular drugs

Macromolecular drugs, such as proteins and nucleic acids, play a pivotal role in treating refractory diseases and hold significant promise in the growing pharmaceutical market. However, without efficient delivery systems, macromolecular drugs are highly susceptible to rapid biodegradation or systemic clearance, underscoring the need for advanced delivery strategies for clinical translation. A major challenge lies in their limited tissue penetration due to large molecular weight and size, which has recently garnered significant attention as it often leads to therapeutic failure or the emergence of resistance. In this review, we first outline the biological barriers limiting macromolecular tissue penetration, then explore the inherent permeation mechanisms of biomacromolecules in biological systems. We then highlight delivery strategies aimed at enhancing the tissue penetration of macromolecular therapeutics, with a particular focus on tissue-adaptive and tissue-remodeling delivery platforms. Finally, we provide a concise perspective on future research directions in deep tissue penetration for biomacromolecules. This review offers a comprehensive summary of recent advancements and presents critical insights into optimizing the therapeutic efficacy of macromolecular drugs.

Transcytosis: an effective mechanism to enhance nanoparticle extravasation and infiltration through biological barriers

Nanoparticles (NPs)1have been explored as drugs carriers for treating tumors and central nervous system (CNS)2diseases and for oral administration. However, they lack satisfactory clinical efficacy due to poor extravasation and infiltration through biological barriers to target tissues. Most clinical antitumor NPs have been designed based on enhanced permeability and retention effects which are insufficient and heterogeneous in human tumors. The tight junctions33TJs: tight junctionsof the blood-brain barrier44BBB: blood-brain barrierand the small intestinal epithelium severely impede NPs from being transported into the CNS and blood circulation, respectively. By contrast, transcytosis enables NPs to bypass these physiological barriers and enhances their infiltration into target tissues by active transport. Here, we systematically review the mechanisms and putative application of NP transcytosis for targeting tumor and CNS tissues, explore oral NP administration, and propose future research directions in the field of NP transcytosis.

Strategies for intravesical drug delivery: From bladder physiological barriers and potential transport mechanisms

Intravesical drug delivery (IDD), as a noninvasive, local pathway of administration, has great clinical significance for bladder diseases, especially bladder cancer. Despite the many advantages of IDD such as enhanced focal drug exposure and avoidance of systemic adverse drug reactions, the effectiveness of drug delivery is greatly challenged by the physiological barriers of the bladder. In this review, the routes and barriers encountered in IDD are first discussed, and attention is paid to the potential internal/mucosal retention and absorption-transport mechanisms of drugs. On this basis, the avoidance, overcoming and utilization of the "three barriers" is further emphasized, and current design and fabrication strategies for intravesical drug delivery systems (IDDSs) are described mainly from the perspectives of constructing drug reservoirs, enhancing permeability and targeting, with the hope of providing systematic understanding and inspirations for the research of novel IDDSs and their treatment of bladder diseases.

Stimulus-Responsive Nanodelivery and Release Systems for Cancer Gene Therapy: Efficacy Improvement Strategies

Introduction of exogenous genes into target cells to overcome various tumor diseases caused by genetic defects or abnormalities and gene therapy, a new treatment method, provides a promising strategy for tumor treatment. Over the past decade, gene therapy has made exciting progress; however, it still faces the challenge of low nucleic acid delivery and release efficiencies. The emergence of nonviral vectors, primarily nanodelivery and release systems (NDRS), has resulted in a historic breakthrough in the application of gene therapy. NDRS, especially stimulus-responsive NDRS that can respond in a timely manner to changes in the internal and external microenvironment (eg, low pH, high concentration of glutathione/reactive oxygen species, overexpressed enzymes, temperature, light, ultrasound, and magnetic field), has shown excellent loading and release advantages in the precision and efficiency of tumor gene therapy and has been widely applied. The only disadvantage is that poor transfection efficiency limits the in-depth application of gene therapy in clinical practice, owing to the presence of biological barriers in the body. Therefore, this review first introduces the development history of gene therapy, the current obstacles faced by gene delivery, strategies to overcome these obstacles, and conventional vectors, and then focuses on the latest research progress in various stimulus-responsive NDRS for improving gene delivery efficiency. Finally, the future challenges and prospects that stimulus-responsive NDRS may face in clinical application and transformation are discussed to provide references for enhancing in-depth research on tumor gene therapy.

Smart Nanoassembly Enabling Activatable NIR Fluorescence and ROS Generation with Enhanced Tumor Penetration for Imaging-Guided Photodynamic Therapy

Fluorescence imaging-guided photodynamic therapy (FIG-PDT) holds promise for cancer treatment, yet challenges persist in poor imaging quality, phototoxicity, and insufficient anti-tumor effect. Herein, a novel nanoplatform, LipoHPM, designed to address these challenges, is reported. This approach employs an acid-sensitive amine linker to connect a biotin-modified hydrophilic polymer (BiotinPEG) with a new hydrophobic photosensitizer (MBA), forming OFF-state BiotinPEG-MBA (PM) micelles via an aggregation-caused quenching (ACQ) effect. These micelles are then co-loaded with the tumor penetration enhancer hydralazine (HDZ) into pH-sensitive liposomes (LipoHPM). Leveraging the ACQ effect, LipoHPM is silent in both fluorescence and reactive oxygen species (ROS) generation during blood circulation but restores both properties upon disassembly. Following intravenous injection in tumor-bearing mice, LipoHPM actively targets tumor cells overexpressing biotin-receptors, contributing to enhanced tumor accumulation. Upon cellular internalization, LipoHPM disassembles within lysosomes, releasing HDZ to enhance tumor penetration and inhibit tumor metastasis. Concurrently, the micelles activate fluorescence for tumor imaging and boost the production of both type-I and type-II ROS for tumor eradication. Therefore, the smart LipoHPM synergistically integrates near-infrared emission, activatable tumor imaging, robust ROS generation, efficient anti-tumor and anti-metastasis activity, successfully overcoming limitations of conventional photosensitizers and establishing itself as a promising nanoplatform for potent FIG-PDT applications.

Effect of biophysical properties of tumor extracellular matrix on intratumoral fate of nanoparticles: Implications on the design of nanomedicine

Nanomedicine has a profound impact on various research domains including drug delivery, diagnostics, theranostics, and regenerative medicine. Nevertheless, the clinical translation of nanomedicines for solid cancer remains limited due to the abundant physiological and pathological barriers in tumor that hinder the intratumoral penetration and distribution of these nanomedicines. In this article, we review the dynamic remodeling of tumor extracellular matrix during the tumor progression, discuss the impact of biophysical obstacles within tumors on the penetration and distribution of nanomedicines within the solid tumor and collect innovative approaches to surmount these obstacles for improving the penetration and accumulation of nanomedicines in tumor. Furthermore, we dissect the challenges and opportunities of the respective approaches, and propose potential avenues for future investigations. The purpose of this review is to provide a perspective guideline on how to effectively enhance the penetration of nanomedicines within tumors using promising methods.

High-Throughput Screening of Surface Engineered Cyanine Nanodots for Active Transport of Therapeutic Antibodies into Solid Tumor

The successful delivery of therapeutic biomacromolecules into solid tumor holds great challenge due to their high resistance to penetrate through the complex tumor microenvironments. Here, active-transporting nanoparticles are harnessed to efficiently deliver biomacromolecular drugs into solid tumors through cell transcytosis. A series of molecularly precise cyanine 5-cored polylysine G5 dendrimers (Cy5 nanodots) with different peripheral amino acids (G5-AA) is prepared. The capability of these positively charged nanodots to induce cell endocytosis, exocytosis, and transcytosis is evaluated via fluorescence-based high-throughput screen. The optimized nanodots (G5-R) are conjugated with αPD-L1 (a therapeutic monoclonal antibody binding to programmed-death ligand 1) (αPD-L1-G5-R) to demonstrate the nanoparticle-mediated tumor active transport. The αPD-L1-G5-R can greatly enhance the tumor-penetration capability through adsorption-mediated transcytosis (AMT). The effectiveness of αPD-L1-G5-R is tested in treating mice bearing partially resected CT26 tumors, mimicking the local immunotherapy of residual tumors post-surgery in clinic. The αPD-L1-G5-R embedded in fibrin gel can efficiently mediate tumor cell transcytosis, and deliver αPD-L1 throughout the tumor, thereby enhancing immune checkpoint blockade, reducing tumor recurrence, and significantly prolonging the survival time. The active-transporting nanodots are promising platforms for efficient tumor delivery of therapeutic biomacromolecules.

Enhancing anti-tumor therapy with agmatine-cholesterol conjugate liposomes: in vitro and in vivo evidence

In this study, we synthesized a novel compound, agmatine-cholesterol conjugate (AG-Chol), to enhance the anti-tumor activity of drug-loaded liposomes. We replaced cholesterol with AG-Chol in preparing doxorubicin hydrochloride (DOX) liposomes by using an active loading method for DOX. We assessed the physical and chemical properties of the resulting AG-Liposomes and evaluated their efficacy in vitro and in vivo. The results showed that AG-Liposomes were stable with high encapsulation efficiency. Compared with the control liposomes, AG-Liposomes exhibited a slower drug release rate in the release medium at pH 6.8. The in vitro cell experiments demonstrated that AG-Liposomes had higher tumor cell uptake rate, stronger migration inhibition rate, higher apoptosis rate, better anti-clonogenic ability, and higher lysosome escape ability than the control liposomes. In vivo distribution results demonstrate that liposomes prepared with AG-Chol instead of cholesterol can significantly enhance their tumor targeting abilities and reduce their distribution to non-targeted sites. In vivo tumor suppression experiments showed that AG-Liposomes had a higher tumor suppression rate than the control liposomes without causing apparent toxicity to normal tissues, as evidenced by histological staining. Therefore, substituting cholesterol with AG-Chol in the preparation of liposomes can result in enhanced lysosome escape, improved tumor targeting, and increased efficacy of anti-tumor drugs.

Nose-to-brain delivery of nanotherapeutics: Transport mechanisms and applications

The blood-brain barrier presents a key limitation to the administration of therapeutic molecules for the treatment of brain disease. While drugs administered orally or intravenously must cross this barrier to reach brain targets, the unique anatomical structure of the olfactory system provides a route to deliver drugs directly to the brain. Entering the brain via receptor, carrier, and adsorption-mediated transcytosis in the nasal olfactory and trigeminal regions has the potential to increase drug delivery. In this review, we introduce the physiological and anatomical structures of the nasal cavity, and summarize the possible modes of transport and the relevant receptors and carriers in the nose-to-brain pathway. Additionally, we provide examples of nanotherapeutics developed for intranasal drug delivery to the brain. Further development of nanoparticles that can be applied to intranasal delivery systems promises to improve drug efficacy and reduce drug resistance and adverse effects by increasing molecular access to the brain. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease.

Functionalized Nanomaterials Capable of Crossing the Blood-Brain Barrier

The blood-brain barrier (BBB) is a specialized semipermeable structure that highly regulates exchanges between the central nervous system parenchyma and blood vessels. Thus, the BBB also prevents the passage of various forms of therapeutic agents, nanocarriers, and their cargos. Recently, many multidisciplinary studies focus on developing cargo-loaded nanoparticles (NPs) to overcome these challenges, which are emerging as safe and effective vehicles in neurotheranostics. In this Review, first we introduce the anatomical structure and physiological functions of the BBB. Second, we present the endogenous and exogenous transport mechanisms by which NPs cross the BBB. We report various forms of nanomaterials, carriers, and their cargos, with their detailed BBB uptake and permeability characteristics. Third, we describe the effect of regulating the size, shape, charge, and surface ligands of NPs that affect their BBB permeability, which can be exploited to enhance and promote neurotheranostics. We classify typical functionalized nanomaterials developed for BBB crossing. Fourth, we provide a comprehensive review of the recent progress in developing functional polymeric nanomaterials for applications in multimodal bioimaging, therapeutics, and drug delivery. Finally, we conclude by discussing existing challenges, directions, and future perspectives in employing functionalized nanomaterials for BBB crossing.

Recent advances in nano/micro systems for improved circulation stability, enhanced tumor targeting, penetration, and intracellular drug delivery: a review

In recent years, nanoparticles (NPs) have been extensively developed as drug carriers to overcome the limitations of cancer therapeutics. However, there are several biological barriers to nanomedicines, which include the lack of stability in circulation, limited target specificity, low penetration into tumors and insufficient cellular uptake, restricting the active targeting toward tumors of nanomedicines. To address these challenges, a variety of promising strategies were developed recently, as they can be designed to improve NP accumulation and penetration in tumor tissues, circulation stability, tumor targeting, and intracellular uptake. In this Review, we summarized nanomaterials developed in recent three years that could be utilized to improve drug delivery for cancer treatments.

GSH/pH dual response drug delivery system for photothermal enhanced gene-immunotherapy

Breast cancer has emerged as a leading cause of mortality among women. Photothermal therapy represents a recent therapeutic modality for eradicating localized tumors, albeit hindered by its limited penetration into tumor tissues. Recognizing the potential of photothermal therapy to induce immunogenic cell death in tumor cells, we explored a gene delivery approach utilizing small interfering RNA targeting programmed death ligand 1 (PD-L1), abbreviated as siPD-L1, to bolster the anti-tumor immune response elicited by this therapy. Nonetheless, the suboptimal release efficiency and inherent instability of RNA molecules have posed challenges to their therapeutic efficacy. In this study, we designed a glutathione (GSH)/pH-responsive micelle system, employing biocompatible and low-toxicity polyethyleneimine in conjunction with structurally robust pluronic P123, to encapsulate both indocyanine green (ICG) and siPD-L1 for precise targeting in breast cancer treatment. The resulting PSP/ICG/siPD-L1 nanocarrier demonstrated admirable biocompatibility and stability. Upon internalization into tumor cells, this nanocarrier exhibited rapid release of both ICG and siPD-L1, responding to the acidic tumor microenvironment and GSH conditions. The inclusion of siPD-L1 effectively downregulated the expression of PD-L1 on the tumor cell surface, thereby impeding tumor growth. Additionally, ICG demonstrated a photothermal effect when exposed to near-infrared light. Both in vitro and in vivo investigations substantiated the nanocarrier's efficacy against tumor cells, culminating in the complete ablation of 4T1 tumors in situ. Consequently, PSP/ICG/siPD-L1 emerges as a promising nanocarrier candidate for augmenting anti-tumor immunity through the synergistic combination of photothermal therapy and gene-based intervention.

Surface chemistry mediates the tumor entrance of nanoparticles probed using single-molecule dual-imaging nanodots

The active transport of nanoparticles into solid tumors through transcytosis has been recognized as a promising way to enhance tumor accumulation and penetration, but the effect of the physicochemical properties of nanoparticles remains unclear. Herein, we develop a type of single-molecule dual imaging nanodot by divergent growth of perylenediimide (PDI)-dye-cored polylysine dendrimers and internal orthogonal conjugation of Gd(III)-based macrocyclic probes for fluorescence imaging and magnetic resonance imaging (MRI) of surface chemistry-dependent tumor entrance. The MRI and fluorescence imaging show that sixth-generation nanodots with acetylated (G6-Ac) and oligo ethylene glycol (G6-OEG) surfaces exhibit similar high tumor accumulation but different intratumor distribution. Cellular uptake and transport experiments suggest that G6-Ac nanodots have lower lysosomal entrapment (61% vs. 83%) and a higher exocytotic rate (47% vs. 29%) than G6-OEG. Therefore, G6-Ac is more likely to undergo intercellular transport through cell transcytosis, and is able to reach a tumor area distant from blood vessels, while G6-OEG mainly enters the tumor through enhanced permeability and retention (EPR) effect-based passive transport, and is not able to deliver to distant tumor areas. This study suggests that it is possible to boost the tumor entrance of nanoparticles by engineering surface chemistry for active transport.

Tumor Abnormality-Oriented Nanomedicine Design

Anticancer nanomedicines have been proven effective in mitigating the side effects of chemotherapeutic drugs. However, challenges remain in augmenting their therapeutic efficacy. Nanomedicines responsive to the pathological abnormalities in the tumor microenvironment (TME) are expected to overcome the biological limitations of conventional nanomedicines, enhance the therapeutic efficacies, and further reduce the side effects. This Review aims to quantitate the various pathological abnormalities in the TME, which may serve as unique endogenous stimuli for the design of stimuli-responsive nanomedicines, and to provide a broad and objective perspective on the current understanding of stimuli-responsive nanomedicines for cancer treatment. We dissect the typical transport process and barriers of cancer drug delivery, highlight the key design principles of stimuli-responsive nanomedicines designed to tackle the series of barriers in the typical drug delivery process, and discuss the "all-into-one" and "one-for-all" strategies for integrating the needed properties for nanomedicines. Ultimately, we provide insight into the challenges and future perspectives toward the clinical translation of stimuli-responsive nanomedicines.

Understanding How Cationic Polymers' Properties Inform Toxic or Immunogenic Responses via Parametric Analysis

Cationic polymers are widely used materials in diverse biotechnologies. Subtle variations in these polymers' properties can change them from exceptional delivery agents to toxic inflammatory hazards. Conventional screening strategies optimize for function in a specific application rather than observing how underlying polymer-cell interactions emerge from polymers' properties. An alternative approach is to map basic underlying responses, such as immunogenicity or toxicity, as a function of basic physicochemical parameters to inform the design of materials for a breadth of applications. To demonstrate the potential of this approach, we synthesized 107 polymers varied in charge, hydrophobicity, and molecular weight. We then screened this library for cytotoxic behavior and immunogenic responses to map how these physicochemical properties inform polymer-cell interactions. We identify three compositional regions of interest and use confocal microscopy to uncover the mechanisms behind the observed responses. Finally, immunogenic activity is confirmed in vivo. Highly cationic polymers disrupted the cellular plasma membrane to induce a toxic phenotype, while high molecular weight, hydrophobic polymers were uptaken by active transport to induce NLRP3 inflammasome activation, an immunogenic phenotype. Tertiary amine- and triethylene glycol-containing polymers did not invoke immunogenic or toxic responses. The framework described herein allows for the systematic characterization of new cationic materials with different physicochemical properties for applications ranging from drug and gene delivery to antimicrobial coatings and tissue scaffolds.

Extracellular Vesicles Facilitate the Transportation of Nanoparticles within and between Cells for Enhanced Tumor Therapy

The interaction between nanoparticles and cells is closely associated with the therapeutic effects of nanomedicine. Nanoparticles could be transported among cells, but the process-related mechanism remains to be further explored. In this study, it was found that endocytosed cationic polymer nanoparticles (cNPs) could be excreted in an extracellular vesicle (EV)-coated form (cNP@EVs). It was deduced that cNPs may pass through early endosomes, multivesicular bodies (MVBs), and autophagic MVBs within cells. Moreover, a high level of autophagy facilitated the exocytosis process. Since EVs were the effective vehicles for conveying biological information and substances, cNP@EVs were proved to be efficient forms for the intercellular transportation of nanoparticles and have the potential as efficient biomimetic drug delivery systems. These properties endowed cNP@EVs with deep penetration and enhanced antitumor activity. Our findings provided a proof-of-concept for understanding the transfer process of nanoparticles among cells and may help us to further utilize EV-mediated transportation of nanoparticles, therefore, expanding its clinical application.

Role of Micelle Size in Cell Transcytosis-Based Tumor Extravasation, Infiltration, and Treatment Efficacy

Transcytosis-based active transport of cancer nanomedicine has shown great promise for enhancing its tumor extravasation and infiltration and antitumor activity, but how the key nanoproperties of nanomedicine, particularly particle size, influence the transcytosis remains unknown. Herein, we used a transcytosis-inducing polymer, poly[2-(N-oxide-N,N-diethylamino)ethyl methacrylate] (OPDEA), and fabricated stable OPDEA-based micelles with different sizes (30, 70, and 140 nm in diameter) from its amphiphilic block copolymer, OPDEA-block-polystyrene (OPDEA-PS). The study of the micelle size effects on cell transcytosis, tumor extravasation, and infiltration showed that the smallest micelles (30 nm) had the fastest transcytosis and, thus, the most efficient tumor extravasation and infiltration. So, the 7-ethyl-10-hydroxyl camptothecin (SN38)-conjugated OPDEA micelles of 30 nm had much enhanced antitumor activity compared with the 140 nm micelles. These results are instructive for the design of active cancer nanomedicine.

Mechanisms and strategies to enhance penetration during intravesical drug therapy for bladder cancer

Bladder cancer (BCa) is one of the most prevalent cancers worldwide. The effectiveness of intravesical therapy for bladder cancer, however, is limited due to the short dwell time and the presence of permeation barriers. Considering the histopathological features of BCa, the permeation barriers for drugs to transport across consist of a mucus layer and a nether tumor physiological barrier. Mucoadhesive delivery systems or mucus-penetrating delivery systems are developed to enhance their retention in or penetration across the mucus layer, but delivery systems that are capable of mucoadhesion-to-mucopenetration transition are more efficient to deliver drugs across the mucus layer. For the tumor physiological barrier, delivery systems mainly rely on four types of penetration mechanisms to cross it. This review summarizes the classical and latest approaches to intravesical drug delivery systems to penetrate BCa.

Polyethyleneimine-based immunoadjuvants for designing cancer vaccines

Despite extensive efforts to improve the effectiveness of cancer vaccines, the lack of immunogenicity remains an issue. Adjuvants are required to enhance the immunogenicity of antigens and activate the immune response. However, only a few adjuvants with acceptable toxicity have sufficient potency for use in cancer vaccines, necessitating the discovery of potent adjuvants. The most well-known cationic polymer polyethyleneimine (PEI) acts as a carrier for delivering antigens, and as an immunoadjuvant for enhancing the innate and adaptive immunity. In this review, we have summarized PEI-based adjuvants and discussed how to improve and boost the immune response to vaccines. We further focused on PEI-based adjuvants in cancer vaccines. Finally, we have proposed the potential challenges and future issues of PEI-based adjuvants to elicit the effectiveness of cancer vaccines.

The role of imaging in targeted delivery of nanomedicine for cancer therapy

Nanomedicines overcome the pharmacokinetic limitations of traditional drug formulations and have promising prospect in cancer treatment. However, nanomedicine delivery in vivo is still facing challenges from the complex physiological environment. For the purpose of effective tumor therapy, they should be designed to guarantee the five features principle, including long blood circulation, efficient tumor accumulation, deep matrix penetration, enhanced cell internalization and accurate drug release. To ensure the excellent performance of the designed nanomedicine, it would be better to monitor the drug delivery process as well as the therapeutic effects by real-time imaging. In this review, we summarize strategies in developing nanomedicines for efficiently meeting the five features of drug delivery, and the role of several imaging modalities (fluorescent imaging (FL), magnetic resonance imaging (MRI), computed tomography (CT), photoacoustic imaging (PAI), positron emission tomography (PET), and electron microscopy) in tracing drug delivery and therapeutic effect in vivo based on five features principle.

Transcytosis-enabled active extravasation of tumor nanomedicine

Extravasation is the first step for nanomedicines in circulation to reach targeted solid tumors. Traditional nanomedicines have been designed to extravasate into tumor interstitium through the interendothelial gaps previously assumed rich in tumor blood vessels, i.e., the enhanced permeability and retention (EPR) effect. While the EPR effect has been validated in animal xenograft tumor models, accumulating evidence implies that the EPR effect is very limited and highly heterogeneous in human tumors, leading to highly unpredictable and inefficient extravasation and thus limited therapeutic efficacy of nanomedicines, including those approved in clinics. Enabling EPR-independent extravasation is the key to develop new generation of nanomedicine with enhanced efficacy. Transcytosis of tumor endothelial cells can confer nanomedicines to actively extravasate into solid tumors without relying on the EPR effect. Here, we review and prospectthe development of transcytosis-inducing nanomedicines, in hope of providing instructive insights for design of nanomedicines that can undergo selective transcellular transport across tumor endothelial cells, and thus inspiring the development of next-generation nanomedicines for clinical translation.

Biomedical polymers: synthesis, properties, and applications

Biomedical polymers have been extensively developed for promising applications in a lot of biomedical fields, such as therapeutic medicine delivery, disease detection and diagnosis, biosensing, regenerative medicine, and disease treatment. In this review, we summarize the most recent advances in the synthesis and application of biomedical polymers, and discuss the comprehensive understanding of their property-function relationship for corresponding biomedical applications. In particular, a few burgeoning bioactive polymers, such as peptide/biomembrane/microorganism/cell-based biomedical polymers, are also introduced and highlighted as the emerging biomaterials for cancer precision therapy. Furthermore, the foreseeable challenges and outlook of the development of more efficient, healthier and safer biomedical polymers are discussed. We wish this systemic and comprehensive review on highlighting frontier progress of biomedical polymers could inspire and promote new breakthrough in fundamental research and clinical translation.