Mucus Penetrating and Cell-Binding Polyzwitterionic Micelles as Potent Oral Nanomedicine for Cancer Drug Delivery

Self-nanomicellizing solid dispersion: A promising platform for oral drug delivery

Amorphous solid dispersion (ASD) has been widely used to enhance the oral bioavailability of water-insoluble drugs for oral delivery because of its advantages of enhancing solubility and dissolution rate. However, the problems related to drug recrystallization after drug dissolution in media or body fluid have constrained its application. Recently, a self-nanomicellizing solid dispersion (SNMSD) has been developed by incorporating self-micellizing polymers as carriers to settle the problems, markedly improving the ability of supersaturation maintenance and enhancing the oral bioavailability of drug. Spontaneous formation and stability of the self-nanomicelle (SNM) have been proved to be the key to supersaturation maintenance of SNMSD system. This offers a novel research direction for maintaining supersaturation and enhancing the bioavailability of ASDs. To delve into the advantages of SNMSDs, we provide a concise review introducing the formation mechanism, characterization methods and stability of SNMs, emphasizing the advantages of SNMSDs for oral drug delivery facilitated by SNM formation, and discussing relevant research prospects.

Brain gliomas: Diagnostic and therapeutic issues and the prospects of drug-targeted nano-delivery technology

Glioma is the most common intracranial malignant tumor, with severe difficulty in treatment and a low patient survival rate. Due to the heterogeneity and invasiveness of tumors, lack of personalized clinical treatment design, and physiological barriers, it is often difficult to accurately distinguish gliomas, which dramatically affects the subsequent diagnosis, imaging treatment, and prognosis. Fortunately, nano-delivery systems have demonstrated unprecedented capabilities in diagnosing and treating gliomas in recent years. They have been modified and surface modified to efficiently traverse BBB/BBTB, target lesion sites, and intelligently release therapeutic or contrast agents, thereby achieving precise imaging and treatment. In this review, we focus on nano-delivery systems. Firstly, we provide an overview of the standard and emerging diagnostic and treatment technologies for glioma in clinical practice. After induction and analysis, we focus on summarizing the delivery methods of drug delivery systems, the design of nanoparticles, and their new advances in glioma imaging and treatment in recent years. Finally, we discussed the prospects and potential challenges of drug-delivery systems in diagnosing and treating glioma.

Nanodrugs based on co-delivery strategies to combat cisplatin resistance

Cisplatin (CDDP), as a broad-spectrum anticancer drug, is able to bind to DNA and inhibit cell division. Despite the widespread use of cisplatin since its discovery, cisplatin resistance developed during prolonged chemotherapy, similar to other small molecule chemotherapeutic agents, severely limits its clinical application. Cisplatin resistance in cancer cells is mainly caused by three reasons: DNA repair, decreased cisplatin uptake/increased efflux, and cisplatin inactivation. In earlier combination therapies, the emergence of multidrug resistance (MDR) in cancer cells prevented the achievement of the desired therapeutic effect even with the accurate combination of two chemotherapeutic drugs. Therefore, combination therapy using nanocarriers for co-delivery of drugs is considered to be ideal for alleviating cisplatin resistance and reducing cisplatin-related toxicity in cancer cells. This article provides an overview of the design of cisplatin nano-drugs used to combat cancer cell resistance, elucidates the mechanisms of action of cisplatin and the pathways through which cancer cells develop resistance, and finally discusses the design of drugs and related carriers that can synergistically reduce cancer resistance when combined with cisplatin.

The mechanical mechanism of angiotensin II induced activation of hepatic stellate cells promoting portal hypertension

In the development of chronic liver disease, the hepatic stellate cell (HSC) plays a pivotal role in increasing intrahepatic vascular resistance (IHVR) and inducing portal hypertension (PH) in cirrhosis. Our research demonstrated that HSC contraction, prompted by angiotensin II (Ang II), significantly contributed to the elevation of type I collagen (COL1A1) expression. This increase was intimately associated with enhanced cell tension and YAP nuclear translocation, mediated through α-smooth muscle actin (α-SMA) expression, microfilaments (MF) polymerization, and stress fibers (SF) assembly. Further investigation revealed that the Rho/ROCK signaling pathway regulated MF polymerization and SF assembly by facilitating the phosphorylation of cofilin and MLC, while Ca2+ chiefly governed SF assembly via MLC. Inhibiting α-SMA-MF-SF assembly changed Ang II-induced cell contraction, YAP nuclear translocation, and COL1A1 expression, findings corroborated in cirrhotic mice models. Overall, our study offers insights into mitigating IHVR and PH through cell mechanics, heralding potential breakthroughs.

Modulating Intracellular Dynamics for Optimized Intracellular Release and Transcytosis Equilibrium

Active transcytosis-mediated nanomedicine transport presents considerable potential in overcoming diverse delivery barriers, thereby facilitating tumor accumulation and penetration. Nevertheless, the persistent challenge lies in achieving a nuanced equilibrium between intracellular interception for drug release and transcytosis for tumor penetration. In this study, a comprehensive exploration is conducted involving a series of polyglutamine-paclitaxel conjugates featuring distinct hydrophilic/hydrophobic ratios (HHR) and tertiary amine-oxide proportions (TP) (OPGA-PTX). The screening process, meticulously focused on delineating their subcellular distribution, transcytosis capability, and tumor penetration, unveils a particularly promising candidate denoted as OPPX, characterized by an HHR of 10:1 and a TP of 100%. OPPX, distinguished by its rapid cellular internalization through multiple endocytic pathways, selectively engages in trafficking to the Golgi apparatus for transcytosis to facilitate accumulation within and penetration throughout tumor tissues and simultaneously sorted to lysosomes for cathepsin B-activated drug release. This study not only identifies OPPX as an exemplary nanomedicine but also underscores the feasibility of modulating subcellular distribution to optimize the active transport capabilities and intracellular release mechanisms of nanomedicines, providing an alternative approach to designing efficient anticancer nanomedicines.

Inhalable metal-organic framework-mediated cuproptosis combined with PD-L1 checkpoint blockade for lung metastasis synergistic immunotherapy

Cuproptosis shows enormous application prospects in lung metastasis treatment. However, the glycolysis, Cu+ efflux mechanisms, and insufficient lung drug accumulation severely restrict cuproptosis efficacy. Herein, an inhalable poly (2-(N-oxide-N,N-diethylamino)ethyl methacrylate) (OPDEA)-coated copper-based metal-organic framework encapsulating pyruvate dehydrogenase kinase 1 siRNA (siPDK) is constructed for mediating cuproptosis and subsequently promoting lung metastasis immunotherapy, namely OMP. After inhalation, OMP shows highly efficient lung accumulation and long-term retention, ascribing to the OPDEA-mediated pulmonary mucosa penetration. Within tumor cells, OMP is degraded to release Cu2+ under acidic condition, which will be reduced to toxic Cu+ to induce cuproptosis under glutathione (GSH) regulation. Meanwhile, siPDK released from OMP inhibits intracellular glycolysis and adenosine-5'-triphosphate (ATP) production, then blocking the Cu+ efflux protein ATP7B, thereby rendering tumor cells more sensitive to OMP-mediated cuproptosis. Moreover, OMP-mediated cuproptosis triggers immunogenic cell death (ICD) to promote dendritic cells (DCs) maturation and CD8+ T cells infiltration. Notably, OMP-induced cuproptosis up-regulates membrane-associated programmed cell death-ligand 1 (PD-L1) expression and induces soluble PD-L1 secretion, and thus synergizes with anti-PD-L1 antibodies (aPD-L1) to reprogram immunosuppressive tumor microenvironment, finally yielding improved immunotherapy efficacy. Overall, OMP may serve as an efficient inhalable nanoplatform and afford preferable efficacy against lung metastasis through inducing cuproptosis and combining with aPD-L1.

Physiological Barriers and Strategies of Lipid-Based Nanoparticles for Nucleic Acid Drug Delivery

Lipid-based nanoparticles (LBNPs) are currently the most promising vehicles for nucleic acid drug (NAD) delivery. Although their clinical applications have achieved success, the NAD delivery efficiency and safety are still unsatisfactory, which are, to a large extent, due to the existence of multi-level physiological barriers in vivo. It is important to elucidate the interactions between these barriers and LBNPs, which will guide more rational design of efficient NAD vehicles with low adverse effects and facilitate broader applications of nucleic acid therapeutics. This review describes the obstacles and challenges of biological barriers to NAD delivery at systemic, organ, sub-organ, cellular, and subcellular levels. The strategies to overcome these barriers are comprehensively reviewed, mainly including physically/chemically engineering LBNPs and directly modifying physiological barriers by auxiliary treatments. Then the potentials and challenges for successful translation of these preclinical studies into the clinic are discussed. In the end, a forward look at the strategies on manipulating protein corona (PC) is addressed, which may pull off the trick of overcoming those physiological barriers and significantly improve the efficacy and safety of LBNP-based NADs delivery.

Medicinal Chemistry of Drugs with N-Oxide Functionalities

Molecules with N-oxide functionalities are omnipresent in nature and play an important role in Medicinal Chemistry. They are synthetic or biosynthetic intermediates, prodrugs, drugs, or polymers for applications in drug development and surface engineering. Typically, the N-oxide group is critical for biomedical applications of these molecules. It may provide water solubility or decrease membrane permeability or immunogenicity. In other cases, the N-oxide has a special redox reactivity which is important for drug targeting and/or cytotoxicity. Many of the underlying mechanisms have only recently been discovered, and the number of applications of N-oxides in the healthcare field is rapidly growing. This Perspective article gives a short summary of the properties of N-oxides and their synthesis. It also provides a discussion of current applications of N-oxides in the biomedical field and explains the basic molecular mechanisms responsible for their biological activity.

Enhanced curcumin transportation across epithelial barrier by mucus-permeable soy protein nanoparticles-mediated dual transcytosis pathways

Nanocarrier-delivered bioactive compounds are highly desirable for their improved stability and applicability, but their bioavailability is still limited due to the strong mucus and epithelial cell barriers. Herein, a series of self-assembled soy protein nanoparticles (SPNPs) with different mucus permeabilities were prepared and their delivery efficiency upon Curcumin (Cur) encapsulation was evaluated. Results demonstrated that the formed SPNPs-Cur exhibited high compatibility and cellular antioxidant accessibility. Besides, SPNPs enhanced the cellular uptake and transmembrane permeation of Cur, especially promoted the transportation of proto-Cur in addition to Cur metabolites. The SPNPs with the rapid mucus diffusion capacity presented more efficient transcytosis across the Caco-2 cell monolayer, which was mediated by a combination of paracellular and transcellular pathways. This work verified that mucus-permeable soy protein nanoparticles could be a promising delivery system for improving the bioavailability of bioactive compounds.

Protein Coronas Derived from Mucus Act as Both Spear and Shield to Regulate Transferrin Functionalized Nanoparticle Transcellular Transport in Enterocytes

The epithelial mucosa is a key biological barrier faced by gastrointestinal, intraoral, intranasal, ocular, and vaginal drug delivery. Ligand-modified nanoparticles demonstrate excellent ability on this process, but their efficacy is diminished by the formation of protein coronas (PCs) when they interact with biological matrices. PCs are broadly implicated in affecting the fate of NPs in vivo and in vitro, yet few studies have investigated PCs formed during interactions of NPs with the epithelial mucosa, especially mucus. In this study, we constructed transferrin modified NPs (Tf-NPs) as a model and explored the mechanisms and effects that epithelial mucosa had on PCs formation and the subsequent impact on the transcellular transport of Tf-NPs. In mucus-secreting cells, Tf-NPs adsorbed more proteins from the mucus layers, which masked, displaced, and dampened the active targeting effects of Tf-NPs, thereby weakening endocytosis and transcellular transport efficiencies. In mucus-free cells, Tf-NPs adsorbed more proteins during intracellular trafficking, which enhanced transcytosis related functions. Inspired by soft coronas and artificial biomimetic membranes, we used mucin as an "active PC" to precoat Tf-NPs (M@Tf-NPs), which limited the negative impacts of "passive PCs" formed during interface with the epithelial mucosa and improved favorable routes of endocytosis. M@Tf-NPs adsorbed more proteins associated with endoplasmic reticulum-Golgi functions, prompting enhanced intracellular transport and exocytosis. In summary, mucus shielded against the absorption of Tf-NPs, but also could be employed as a spear to break through the epithelial mucosa barrier. These findings offer a theoretical foundation and design platform to enhance the efficiency of oral-administered nanomedicines.

Ursodeoxycholic Acid-Decorated Zwitterionic Nanoparticles for Orally Liver-Targeted Close-Looped Insulin Delivery

Oral insulin therapies targeting the liver and further simulating close-looped secretion face significant challenges due to multiple trans-epithelial barriers. Herein, ursodeoxycholic acid (UDCA)-decorated zwitterionic nanoparticles (NPs) (UC-CMs@ins) are designed to overcome these barriers, target the liver, and respond to glycemia, thereby achieving oral one-time-per-day therapy. UC-CMs@ins show excellent mucus permeability through the introduction of zwitterion (carboxy betaine, CB). Furthermore, UC-CMs@ins possess superior cellular internalization via proton-assisted amino acid transporter 1 (PAT1, CB-receptor) and apical sodium-dependent bile acid transporter (ASBT, UDCA-receptor) pathways. Moreover, UC-CMs@ins exhibit excellent endolysosomal escape ability and improve the basolateral release of insulin into the bloodstream via the ileal bile acid-binding protein and the heteromeric organic solute transporter (OSTα- OSTβ) routes compared with non-UDCA-decorated C-CMs@ins. Therefore, CB and UDCA jointly overcome mucus and intestinal barriers. Additionally, UC-CMs@ins prevent insulin degradation in the gastrointestinal tract for crosslinked structure, improve insulin accumulation in the liver for UDCA introduction, and effectively regulate glycemia for "closed-loop" glucose control. Surprisingly, oral ingestion of UC-CMs@ins shows a superior effect on glycemia (≈22 h, normoglycemia) and improves postprandial glycemic levels in diabetic mice, illustrating the enormous potential of the prepared NPs as a platform for oral insulin administration in diabetes treatment.

Generation of a Hydrophobic Protrusion on Nanoparticles to Improve the Membrane-Anchoring Ability and Cellular Internalization

Controlling the nanoparticle-cell membrane interaction to achieve easy and fast membrane anchoring and cellular internalization is of great importance in a variety of biomedical applications. Here we report a simple and versatile strategy to maneuver the nanoparticle-cell membrane interaction by creating a tunable hydrophobic protrusion on Janus particles through swelling-induced symmetry breaking. When the Janus particle contacts cell membrane, the protrusion will induce membrane wrapping, leading the particles to docking to the membrane, followed by drawing the whole particles into the cell. The efficiencies of both membrane anchoring and cellular internalization can be promoted by optimizing the size of the protrusion. In vitro, the Janus particles can quickly anchor to the cell membrane in 1 h and be internalized within 24 h, regardless of the types of cells involved. In vivo, the Janus particles can effectively anchor to the brain and skin tissues to provide a high retention in these tissues after intracerebroventricular, intrahippocampal, or subcutaneous injection. This strategy involving the creation of a hydrophobic protrusion on Janus particles to tune the cell-membrane interaction holds great potential in nanoparticle-based biomedical applications.

Recent advances in oral insulin delivery technologies

With the rise in diabetes mellitus cases worldwide, oral delivery of insulin is preferred over subcutaneous insulin administration due to its good patient compliance and non-invasiveness, simplicity, and versatility. However, oral insulin delivery is hampered by various gastrointestinal barriers that result in low drug bioavailability and insufficient therapeutic efficiency. Numerous strategies have been developed to overcome these barriers and increase the bioavailability of oral insulin. Yet, no commercial oral insulin product is available to address all clinical hurdles because of various substantial obstacles related to the structural organization and physiological function of the gastrointestinal tract. Herein, we discussed the significant physiological barriers (including chemical, enzymatic, and physical barriers) that hinder the transportation and absorption of orally delivered insulin. Then, we showcased recent significant and innovative advances in oral insulin delivery technologies. Finally, we concluded the review with remarks on future perspectives on oral insulin delivery technologies and potential challenges for forthcoming clinical translation of oral insulin delivery technologies.

Oral Nanomedicine: Challenges and Opportunities

Compared to injection administration, oral administration is free of discomfort, wound infection, and complications and has a higher compliance rate for patients with diverse diseases. However, oral administration reduces the bioavailability of medicines, especially biologics (e.g., peptides, proteins, and antibodies), due to harsh gastrointestinal biological barriers. In this context, the development and prosperity of nanotechnology have helped improve the bioactivity and oral availability of oral medicines. On this basis, first, the biological barriers to oral administration are discussed, and then oral nanomedicine based on organic and inorganic nanomaterials and their biomedical applications in diverse diseases are reviewed. Finally, the challenges and potential opportunities in the future development of oral nanomedicine, which may provide a vital reference for the eventual clinical transformation and standardized production of oral nanomedicine, are put forward.

Recent advances in zwitterionic nanoscale drug delivery systems to overcome biological barriers

Nanoscale drug delivery systems (nDDS) have been employed widely in enhancing the therapeutic efficacy of drugs against diseases with reduced side effects. Although several nDDS have been successfully approved for clinical use up to now, biological barriers between the administration site and the target site hinder the wider clinical adoption of nDDS in disease treatment. Polyethylene glycol (PEG)-modification (or PEGylation) has been regarded as the gold standard for stabilising nDDS in complex biological environment. However, the accelerated blood clearance (ABC) of PEGylated nDDS after repeated injections becomes great challenges for their clinical applications. Zwitterionic polymer, a novel family of anti-fouling materials, have evolved as an alternative to PEG due to their super-hydrophilicity and biocompatibility. Zwitterionic nDDS could avoid the generation of ABC phenomenon and exhibit longer blood circulation time than the PEGylated analogues. More impressively, zwitterionic nDDS have recently been shown to overcome multiple biological barriers such as nonspecific organ distribution, pressure gradients, impermeable cell membranes and lysosomal degradation without the need of any complex chemical modifications. The realization of overcoming multiple biological barriers by zwitterionic nDDS may simplify the current overly complex design of nDDS, which could facilitate their better clinical translation. Herein, we summarise the recent progress of zwitterionic nDDS at overcoming various biological barriers and analyse their underlying mechanisms. Finally, prospects and challenges are introduced to guide the rational design of zwitterionic nDDS for disease treatment.

An Oral Nanomedicine Elicits In Situ Vaccination Effect against Colorectal Cancer

Oral administration is the most preferred approach for treating colon diseases, and in situ vaccination has emerged as a promising cancer therapeutic strategy. However, the lack of effective drug delivery platforms hampered the application of in situ vaccination strategy in oral treatment of colorectal cancer (CRC). Here, we construct an oral core-shell nanomedicine by preparing a silk fibroin-based dual sonosensitizer (chlorin e6, Ce6)- and immunoadjuvant (imiquimod, R837)-loaded nanoparticle as the core, with its surface coated with plant-extracted lipids and pluronic F127 (p127). The resultant nanomedicines (Ce6/R837@Lp127NPs) maintain stability during their passage through the gastrointestinal tract and exert improved locomotor activities under ultrasound irradiation, achieving efficient colonic mucus infiltration and specific tumor penetration. Thereafter, Ce6/R837@Lp127NPs induce immunogenic death of colorectal tumor cells by sonodynamic treatment, and the generated neoantigens in the presence of R837 serve as a potent in situ vaccine. By integrating with immune checkpoint blockades, the combined treatment modality inhibits orthotopic tumors, eradicates distant tumors, and modulates intestinal microbiota. As the first oral in situ vaccination, this work spotlights a robust oral nanoplatform for producing a personalized vaccine against CRC.

Amplified Targeted Drug Delivery Independent of Target Number through Alternative Administration of Two Matched Nanoparticles

Targeting nanoparticles (NPs) based on the specific binding of ligands with molecular targets provides a promising tool for tissue-selective drug delivery. However, the number of molecular targets on the cell surface is limited, hindering the number of NPs that can bind and, thus, limiting the therapeutic outcome. Although several strategies have been developed to enhance drug delivery, such as enhancing drug loading and circulation time or increasing the enhanced permeability and retention effect of nanocarriers, none have resolved this issue. Herein, we designed a simple method for amplified and targeted drug delivery using two matched NPs. One NP was aptamer-functionalized to specifically bind to target cells, while the other was aptamer-complementary DNA-functionalized to specifically bind to aptamer-NPs. Alternate administration of the two matched NPs enables their continuous accumulation in the disease site despite their limited molecular targets. As a proof of concept, the method was tested in a breast cancer model and significantly enhanced chemotherapy of tumor cells in vitro and in vivo. The potential applications of this method in a brain injury model were also demonstrated. Overall, the study describes a method for amplified targeted drug delivery independent of the target number.

Hyaluronic acid/inulin-based nanocrystals with an optimized ratio of indigo and indirubin for combined ulcerative colitis therapy via immune and intestinal flora regulation

Indigo (IND) and indirubin (INB) have demonstrated a synergistic effect in treating ulcerative colitis at a ratio of 7.5:1. However, the colon mucus layer, a critical physiological barrier against external threats, is also a biological barrier, limiting the potential for effective drug delivery to the lamina propria for regulating inflammatory cells. Inspired by the potential of Hyaluronic acid (HA), to enhance cellular uptake by inflammatory cells, and Pluronic® F127 (F127), known for overcoming the mucus barrier, this study innovatively developed INB/IND nanosuspensions by co-modifying with F127 and HA. Moreover, inulin serves a dual purpose as a spray protective agent and a regulator of intestinal flora. Therefore, it was incorporated into INB/IND nanosuspensions for subsequent spray drying, resulting in the preparation of INB/IND nanocrystals (INB/IND-NC). The mucus penetration of INB/IND-NC was 24.30 times that of the control group. Besides, INB/IND-NC exhibited enhanced cellular uptake properties proximately twice that of Raw INB/IND. Importantly, INB/IND-NC exhibited improved therapeutic efficacy in DSS-induced mice by regulating the expression of cytokines, regulating immune responses via downregulating the expression of macrophages, neutrophils, and dendritic cells and maintaining intestinal flora homeostasis. Our study provides a new perspective for applying natural products for treating inflammatory diseases.

Cell-Selective Binding Zwitterionic Polymeric Micelles Boost the Delivery Efficiency of Antibiotics

Effective accumulation and penetration of antibiotics in the biofilm are critical issues for bacterial infection treatment. Red blood cells (RBCs) have been widely utilized to hitchhike nanocarriers for drug delivery. It is vital and challenging to find a nanocarrier with an appropriate affinity toward RBCs and bacteria for selective hitchhiking and release that determines the drug delivery efficiency and specificity. Herein, we report a zwitterionic polymer poly(2-(N-oxide-N,N-diethylamino)ethyl methacrylate) (OPDEA)-based micelle, which can hitchhike on RBCs in blood and preferentially release in the infection site. We found that OPDEA could bind to the RBCs cell membrane via phospholipid-related affinity and transfer to Gram-positive bacteria due to nearly an order of magnitude stronger interaction with the bacteria cell wall. The zwitterionic surface and cell-wall affinity of OPDEA-based micelles also promote their penetration in biofilm. The clarithromycin-loaded OPDEA micelles show efficient drug delivery into the infection site, resulting in excellent therapeutic performance in both peritonitis and pneumonia models by intravenous or spray administration. This simple RBC-selective hitchhiking and releasing antibiotic delivery system provides a promising strategy for the design of antibacterial nanomedicines.

Antifouling Properties of Amine-Oxide-Containing Zwitterionic Polymers

Biofouling due to nonspecific proteins or cells on the material surfaces is a major challenge in a range of applications such as biosensors, medical devices, and implants. Even though poly(ethylene glycol) (PEG) has become the most widely used stealth material in medical and pharmaceutical products, the number of reported cases of PEG-triggered rare allergic responses continues to increase in the past decades. Herein, a new type of antifouling material poly(amine oxide) (PAO) has been evaluated as an alternative to overcome nonspecific foulant adsorption and impart comparable biocompatibility. Alkyl-substituted PAO containing diethyl, dibutyl, and dihexyl substituents are prepared, and their solution properties are studied. Photoreactive copolymers containing benzophenone as the photo-cross-linker are prepared by reversible addition-fragmentation chain-transfer polymerization and fully characterized by gel permeation chromatography and dynamic light scattering. Then, these water-soluble polymers are anchored onto a silicon wafer with the aid of UV irradiation. By evaluating the fouling resistance properties of these modified surfaces against various types of foulants, protein adsorption and bacterial attachment assays show that the cross-linked PAO-modified surface can efficiently inhibit biofouling. Furthermore, human blood cell adhesion experiments demonstrate that our PAO polymer could be used as a novel surface modifier for biomedical devices.

Biodegradable polyester-based nano drug delivery system in cancer chemotherapy: a review of recent progress (2021-2023)

Cancer presents a formidable threat to human health, with the majority of cases currently lacking a complete cure. Frequently, chemotherapy drugs are required to impede its progression. However, these drugs frequently suffer from drawbacks such as poor selectivity, limited water solubility, low bioavailability, and a propensity for causing organ toxicity. Consequently, a concerted effort has been made to seek improved drug delivery systems. Nano-drug delivery systems based on biodegradable polyesters have emerged as a subject of widespread interest in this pursuit. Extensive research has demonstrated their potential for offering high bioavailability, effective encapsulation, controlled release, and minimal toxicity. Notably, poly (ε-caprolactone) (PCL), poly (lactic-co-glycolic acid) (PLGA), and polylactic acid (PLA) have gained prominence as the most widely utilized options as carriers of the nano drug delivery system. This paper comprehensively reviews recent research on these materials as nano-carriers for delivering chemotherapeutic drugs, summarizing their latest advancements, acknowledging their limitations, and forecasting future research directions.

Betaine-Based and Polyguanidine-Inserted Zwitterionic Micelle as a Promising Platform to Conquer the Intestinal Mucosal Barrier

Developing nanocarriers for oral drug delivery is often hampered by the dilemma of balancing mucus permeation and epithelium absorption, since huge differences in surface properties are required for sequentially overcoming these two processes. Inspired by mucus-penetrating viruses that universally possess a dense charge distribution with equal opposite charges on their surfaces, we rationally designed and constructed a poly(carboxybetaine)-based and polyguanidine-inserted cationic micelle platform (hybrid micelle) for oral drug delivery. The optimized hybrid micelle exhibited a great capacity for sequentially overcoming the mucus and villi barriers. It was demonstrated that a longer zwitterionic chain was favorable for mucus diffusion for hybrid micelles but not conducive to cellular uptake. In addition, the significantly enhanced internalization absorption of hybrid micelles was attributed to the synergistic effect of polyguanidine and proton-assisted amine acid transporter 1 (PAT1). Moreover, the retrograde pathway was mainly involved in the intracellular transport of hybrid micelles and transcytosis delivery. Furthermore, the prominent intestinal mucosa absorption in situ and in vivo liver distribution of the oral hybrid micelle were both detected. The results of this study indicated that the hybrid micelles were capable of conquering the intestinal mucosal barrier, having a great potential for oral application of drugs with poor oral bioavailability.

Hyaluronic Acid-Conjugated Fluorescent Probe-Shielded Polydopamine Nanomedicines for Targeted Imaging and Chemotherapy of Bladder Cancer

Bladder cancer is one of the most common malignancies in the urinary system, with high risk of recurrence and progression. However, the difficulty in detecting small tumor lesions and the lack of selectivity of intravesical treatment seriously affect the prognosis of patients with bladder cancer. In the present work, a nanoparticle-based delivery system with tumor targeting, high biocompatibility, simple preparation, and the ability to synergize imaging and therapy was fabricated. Specifically, this nanosystem consisted of the core of doxorubicin (DOX)-loaded polydopamine nanoparticles (PDD NPs) and the shell of hyaluronic acid (HA)-conjugated IR780 (HA-IR780). The HA-IR780-covered PDD NPs (HR-PDD NPs) demonstrated tumor targeting and visualization both in vitro and in vivo with properties of promoted cancer cell endocytosis and lysosomal escape, efficiently delivering drugs to the target site and exerting a killing effect on tumor cells. Encouragingly, intravesical instillation of HR-PDD NPs improved drug retention in the bladder and promoted its accumulation in tumor tissue, resulting in better tumor proliferation inhibition and apoptosis in an orthotopic bladder cancer model in rats. This study provides a promising strategy for the diagnosis and therapy of bladder cancer.

Bioinspired fine-tuning of the mechanical rigidity of SNEDDS for the efficient crossing of multiple gastrointestinal barriers

Nanoproperties, such as size, charge, and rigidity, have been demonstrated to be crucial for nanovehicles to overcome numerous gastrointestinal obstacles. However, the facile approach of modifying the rigidity of nanovehicles remains scarce, limiting understanding of how rigidity impacts their oral delivery. Inspired by the fact that cellular phospholipid content regulates plasma membrane rigidity, the rigidity of self-nanoemulsifiying drug delivery system (SNEDDS) could be fine-tuned via phosphocholine content while their size and zeta potential remain unchanged, using insulin as a model drug. Notably, soft SNEDDS exerted longer gastrointestinal transit time, higher drug release rate, stronger gastrointestinal stability and relatively lower mucus permeation but superior epithelial transcytosis than their hard counterparts in a macropinocytosis-dependent manner. The rigidity-related enhanced transcytosis was attributed to improved endocytosis, lysosome escape capability and exocytosis. Rats with type 1 diabetes exhibited greater oral insulin absorption and blood glucose lowering effect with soft SNEDDS. This study demonstrated the regulatory role of phospholipids in nanovehicle rigidity, which could help develop mechanically optimized nanomedicines in the future.

Nano-enabled colorectal cancer therapy

Colorectal cancer (CRC), one of the most common and deadliest diseases worldwide, poses a great health threat and social burden. The clinical treatments of CRC encompassing surgery, chemotherapy, and radiotherapy are challenged with toxicity, therapy resistance, and recurrence. In the past two decades, targeted therapy and immunotherapy have greatly improved the therapeutic benefits of CRC patients but they still suffer from drug resistance and low response rates. Very recently, gut microbiota regulation has exhibited a great potential in preventing and treating CRC, as well as in modulating the efficacy and toxicity of chemotherapy and immunotherapy. In this review, we provide a cutting-edge summary of nanomedicine-based treatment in colorectal cancer, highlighting the recent progress of oral and systemic tumor-targeting and/or tumor-activatable drug delivery systems as well as novel therapeutic strategies against CRC, including nano-sensitizing immunotherapy, anti-inflammation, gut microbiota modulation therapy, etc. Finally, the recent endeavors to address therapy resistance, metastasis, and recurrence in CRC were discussed. We hope this review could offer insight into the design and development of nanomedicines for CRC and beyond.

Deep-penetration functionalized cuttlefish ink nanoparticles for combating wound infections with synergetic photothermal-immunologic therapy

The challenge of wound infections post-surgery and open trauma caused by multidrug-resistant bacteria poses a constant threat to clinical treatment. As a promising antimicrobial treatment, photothermal therapy can effectively resolve the problem of drug resistance in conventional antibiotic antimicrobial therapy. Here, we report a deep-penetration functionalized cuttlefish ink nanoparticle (CINP) for photothermal and immunological therapy of wound infections. CINP is decorated with zwitterionic polymer (ZP, namely sulfobetaine methacrylate-methacrylate copolymer) to form CINP@ZP nanoparticles. Natural CINP is found to not only exhibit photothermal destruction of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli), but also trigger macrophages-related innate immunity and enhance their antibacterial functions. The ZP coating on the surface of CINP enables nanoparticles to penetrate into deeply infected wound environment. In addition, CINP@ZP is further integrated into the thermosensitive Pluronic F127 gel (CINP@ZP-F127). After in situ spraying gel, CINP@ZP-F127 is also documented notable antibacterial effects in mice wound models infected with MRSA and E. coli. Collectively, this approach combining of photothermal therapy with immunotherapy can promote delivery efficiency of nanoparticles to the deep foci of infective wounds, and effectively eliminate wound infections.

Chain-extension in hyperbranched polymers alters tissue distribution and cytotoxicity profiles in orthotopic models of triple negative breast cancers

The therapeutic efficacy of nanomedicines is highly dependent on their access to target sites in the body, and this in turn is markedly affected by their size, shape and transport properties in tissue. Although there have been many studies in this area, the ability to design nanomaterials with optimal physicochemical properties for in vivo efficacy remains a significant challenge. In particular, it is often difficult to quantify the detailed effects of cancer drug delivery systems in vivo as tumour volume reduction, a commonly reported marker of efficacy, does not always correlate with cytotoxicity in tumour tissue. Here, we studied the behaviour in vivo of two specific poly(2-hydroxypropyl methacrylamide) (pHPMA) pro-drugs, with hyperbranched and chain-extended branched architectures, redox-responsive backbone components, and pH-sensitive linkers to the anti-cancer drug doxorubicin. Evaluation of the biodistribution of these polymers following systemic injection indicated differences in the circulation time and organ distribution of the two polymers, despite their very similar hydrodynamic radii (∼10 and 15 nm) and architectures. In addition, both polymers showed improved tumour accumulation in orthotopic triple-negative breast cancers in mice, and decreased accumulation in healthy tissue, as compared to free doxorubicin, even though neither polymer-doxorubicin pro-drug decreased overall tumour volume as much as the free drug under the dosing regimens selected. However, the results of histopathological examinations by haematoxylin and eosin, and TUNEL staining indicated a higher population of apoptotic cells in the tumours for both polymer pro-drug treatments, and in turn a lower population of apoptotic cells in the heart, liver and spleen, as compared to free doxorubicin treatment. These data suggest that the penetration of these polymer pro-drugs was enhanced in tumour tissue relative to free doxorubicin, and that the combination of size, architecture, bioresponsive backbone and drug linker degradation yielded greater efficacy for the polymers as measured by biomarkers than that of tumour volume. We suggest therefore that the effects of nanomedicines may be different at various length scales relative to small molecule free drugs, and that penetration into tumour tissue for some nanomedicines may not be as problematic as prior reports have suggested. Furthermore, the data indicate that dual-responsive crosslinked polymer-prodrugs in this study may be effective nanomedicines for breast cancer chemotherapy, and that endpoints beyond tumour volume reduction can be valuable in selecting candidates for pre-clinical trials.

Butyrate Modification Promotes Intestinal Absorption and Hepatic Cancer Cells Targeting of Ferroptosis Inducer Loaded Nanoparticle for Enhanced Hepatocellular Carcinoma Therapy

Sorafenib is an oral-administered first-line drug for hepatocellular carcinoma (HCC) treatment. However, the therapeutic efficacy of sorafenib is relatively low. Here, an oral delivery platform that increases sorafenib uptake by HCC and induces potent ferroptosis is designed. This platform is butyrate-modified nanoparticles separately encapsulated with sorafenib and salinomycin. The multifunctional ligand butyrate interacts with monocarboxylate transporter 1 (MCT-1) to facilitate transcytosis. Specifically, MCT-1 is differentially expressed on the apical and basolateral sides of the intestine, highly expressed on the surface of HCC cells but lowly expressed on normal hepatocytes. After oral administration, this platform is revealed to boost transepithelial transport effectively and continuously in the intestine, drug accumulation in the liver, and HCC cell uptake. Following drug release in cancer cells, sorafenib depletes glutathione peroxidase 4 and glutathione, consequently initiating ferroptosis. Meanwhile, salinomycin enhances intracellular iron and lipid peroxidation, thereby accelerating ferroptosis. In vivo experiments performed on the orthotopic HCC model demonstrate that this combination strategy induces pronounced ferroptosis damage and ignites a robust systemic immune response, leading to the effective elimination of tumors and establishment of systemic immune memory. This work provides a proof-of-concept demonstration that an oral delivery strategy for ferroptosis inducers may be beneficial for HCC treatment.

Kinetically Controlled Star Copolymer Self-Assembly for Rapid Fabrication of Nanoparticles with High Encapsulation Capacity

Rapid and scalable self-assembly of an amphiphilic 21-arm star copolymer, (polystyrene-block-polyethylene glycol)21 [(PS-b-PEG)21 ] in aqueous solution has been performed by reverse solvent exchange procedure. Transmission electron microscope (TEM) and nanoparticle tracking analysis (NTA) reveal the formation of nanoparticles with narrow size distribution. Further investigation indicates a kinetically controlled self-assembly mechanism of the copolymers, in which the star topology of the amphiphilic copolymer and deep quenching condition by reverse solvent exchange are key to accelerate intrachain contraction of the copolymer during phase separation. When interchain contraction dominant over interchain association, nanoparticles with low aggregation number could be formed. Thanks to the high hydrophobic contents of the (PS-b-PEG)21 polymers, the resulted nanoparticles could encapsulate a high capacity of hydrophobic cargo up to 19.84 %. The kinetically controlled star copolymer self-assembly process reported here provides a platform for the rapid and scalable fabrication of nanoparticle with high drug loading capacity (LC), which may find broad range of applications in, for example drug delivery, nanopesticide.

Self-assembled nanoformulations of paclitaxel for enhanced cancer theranostics

Chemotherapy has occupied the critical position in cancer therapy, especially towards the post-operative, advanced, recurrent, and metastatic tumors. Paclitaxel (PTX)-based formulations have been widely used in clinical practice, while the therapeutic effect is far from satisfied due to off-target toxicity and drug resistance. The caseless multi-components make the preparation technology complicated and aggravate the concerns with the excipients-associated toxicity. The self-assembled PTX nanoparticles possess a high drug content and could incorporate various functional molecules for enhancing the therapeutic index. In this work, we summarize the self-assembly strategy for diverse nanodrugs of PTX. Then, the advancement of nanodrugs for tumor therapy, especially emphasis on mono-chemotherapy, combinational therapy, and theranostics, have been outlined. Finally, the challenges and potential improvements have been briefly spotlighted.

Versatile flexible micelles integrating mucosal penetration and intestinal targeting for effectively oral delivery of paclitaxel

The extremely low bioavailability of oral paclitaxel (PTX) mainly due to the complicated gastrointestinal environment, the obstruction of intestinal mucus layer and epithelium barrier. Thus, it is of great significance to construct a coordinative delivery system which can overcome multiple intestinal physicochemical obstacles simultaneously. In this work, a high-density PEGylation-based glycocholic acid-decorated micelles (PTX@GNPs) was constructed by a novel polymer, 9-Fluorenylmethoxycarbonyl-polyethylene glycocholic acid (Fmoc-PEG-GCA). The Fmoc motif in this polymer could encapsulate PTX via π‒π stacking to form the core of micelles, and the low molecular weight and non-long hydrophobic chain of Fmoc ensures the high-density of PEG. Based on this versatile and flexible carriers, PTX@GNPs possess mucus trapping escape ability due to the flexible PEG, and excellent intestine epithelium targeting attributed to the high affinity of GCA with apical sodium-dependent bile acid transporter. The in vitro and in vivo results showed that this oral micelle could enhance oral bioavailability of PTX, and exhibited similar antitumor efficacy to Taxol injection via intravenous route. In addition, oral PTX@GNPs administered with lower dosage within shorter interval could increase in vivo retention time of PTX, which supposed to remodel immune microenvironment and enhance oral chemotherapy efficacy by synergistic effect.

Recent progress of micro/nanomotors to overcome physiological barriers in the gastrointestinal tract

Oral administration is a convenient administration route for gastrointestinal disease therapy with good patient compliance. But the nonspecific distribution of the oral drugs may cause serious side effects. In recent years, oral drug delivery systems (ODDS) have been applied to deliver the drugs to the gastrointestinal disease sites with decreased side effects. However, the delivery efficiency of ODDS is tremendously limited by physiological barriers in the gastrointestinal sites, such as the long and complex gastrointestinal tract, mucus layer, and epithelial barrier. Micro/nanomotors (MNMs) are micro/nanoscale devices that transfer various energy sources into autonomous motion. The outstanding motion characteristics of MNMs inspired the development of targeted drug delivery, especially the oral drug delivery. However, a comprehensive review of oral MNMs for the gastrointestinal diseases therapy is still lacking. Herein, the physiological barriers of ODDS were comprehensively reviewed. Afterward, the applications of MNMs in ODDS for overcoming the physiological barriers in the past 5 years were highlighted. Finally, future perspectives and challenges of MNMs in ODDS are discussed as well. This review will provide inspiration and direction of MNMs for the therapy of gastrointestinal diseases, pushing forward the clinical application of MNMs in oral drug delivery.

Biocompatible smart micro/nanorobots for active gastrointestinal tract drug delivery

INTRODUCTION

Oral delivery is the most commonly used route of drug administration owing to good patient compliance. However, the gastrointestinal (GI) tract contains multiple physiological barriers that limit the absorption efficiency of conventional passive delivery systems resulting in a low drug concentration reaching the diseased sites. Micro/nanorobots can convert energy to self-propulsive force, providing a novel platform to actively overcome GI tract barriers for noninvasive drug delivery and treatment.

AREAS COVERED

In this review, we first describe the microenvironments and barriers in the different compartments of the GI tract. Afterward, the applications of micro/nanorobots to overcome GI tract barriers for active drug delivery are highlighted and discussed. Finally, we summarize and discuss the challenges and future prospects of micro/nanorobots for further clinical applications.

EXPERT OPINION

Micro/nanorobots with the ability to autonomously propel themselves and to load, transport, and release payloads on demand are ideal carriers for active oral drug delivery. Although there are many challenges to be addressed, micro/nanorobots have great potential to introduce a new era of drug delivery for precision therapy.

Recent advances in mucus-penetrating nanomedicines for oral treatment of colonic diseases

INTRODUCTION

Oral administration is the most common route for treating colonic diseases that present increased incidences in recent years. Colonic mucus is a critical rate-limiting barrier for the accumulation of oral therapeutics in the colonic tissues. To overcome this obstacle, mucus-penetrating nanotherapeutics have been exploited to increase the accumulated amounts of drugs in the diseased sites and improve their treatment outcomes against colonic diseases.

AREAS COVERED

In this review, we introduce the structure and composition of colonic mucus as well as its impact on the bioavailability of oral drugs. We also introduce various technologies used in the construction of mucus-penetrating nanomedicines (e.g. surface modification of polymers, physical means and biological strategies) and discuss their mechanisms and potential techniques for improving mucus penetration of nanotherapeutics.

EXPERT OPINION

The mucus barrier is often overlooked in oral drug delivery. The weak mucus permeability of conventional medications greatly lowers drug bioavailability. This challenge can be addressed through physical, chemical and biological technologies. In addition to the reported methods, promising approaches may be discovered through interdisciplinary research that further helps enhance the mucus penetration of nanomedicines.

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.

"One-for-All" approach: a black technology for nanomedicine development?

Cancer nanomedicines require different, even opposite, properties to voyage the cascade drug delivery process involving a series of biological barriers. Currently-approved nanomedicines can only alleviate adverse effects but cannot improve patient survival because they fail to meet all the requirements. Therefore, nanocarriers with synchronized functions are highly requisite to capacitate efficient drug delivery and enhanced therapeutic efficacies. This perspective article summarizes recent advances in the two main strategies for nanomedicine design, the All-in-One approach (integration of all the functions in one system) and the One-for-All approach (one functional group with proper affinity enables all the functions), and presents our views on future nanomedicine development.

Orally Administrable H2 S-Scavenging Metal-Organic Framework Prepared by Co-Flow Microfluidics for Comprehensive Restoration of Intestinal Milieu

Intestinal milieu disorders are strongly related to the occurrence of inflammatory bowel diseases (IBDs), which results from mucosa destruction, epithelium disruption, and tight junction (TJ) proteins loss. Excess of H₂ S in the intestinal milieu produced by the sulfate-reducing bacteria metabolism contributes to development of IBDs via epithelial barrier breakdown. Conventional interventions, such as surgery and anti-inflammatory medications, are considered not completely effective because of frequent recurrence and other complications. Herein, a novel oral delivery system, a hydroxypropyl methylcellulose acetate succinate (HPMCAS)-based polymer-coated Zr-based metal-organic framework (UiO-66) with a Cu_x -rhodamine B (CR) probe (hereinafter referred to as HUR), is produced via a co-flow microfluidic approach with the ability to reduce H₂ S levels, thus restoring the intestinal lumen milieu. HPMCAS serves as an enteric coating that exposes UiO-66@CR at the pH of the intestine but not the acidic pH of the stomach. The synthesized HUR exhibits notable therapeutic efficacy, including mucosa recovery, epithelium integrity restoration, and TJ proteins upregulation via H₂ S scavenging to protect against intestinal barrier damage and microbiome dysbiosis. Thus, HUR is verified to be a promising theranostic platform able to decrease the H₂ S content for intestinal milieu disorder treatment. The presented study therefore opens the door for further exploitation for IBDs therapy.

zwitterionic Pluronic analog-coated PLGA nanoparticles for oral insulin delivery

In recent years, zwitterionic materials have drawn great attention in oral drug delivery system due to their capacity for rapid mucus diffusion and enhanced cellular internalization. However, zwitterionic materials tend to show strong polarity that was hard to directly coat hydrophobic nanoparticles (NPs). Inspired by Pluronic coating, a simple and convenient strategy to coat NPs with zwitterionic materials using zwitterionic Pluronic analogs was developed in this investigation. Poly(carboxybetaine)-poly(propylene oxide)-Poly(carboxybetaine) (PCB-PPO-PCB, PPP), containing PPO segments with MW > 2.0 kDa, can effectively adsorb on the surface of PLGA NPs with typical core-shell spherical in shape. The PLGA@PPP4K NPs were stable in gastrointestinal physiological environment and sequentially conquered mucus and epithelium barriers. Proton-assisted amine acid transporter 1 (PAT1) was verified to contribute to the enhanced internalization of PLGA@PPP4K NPs, and the NPs could partially evade lysosomal degradation pathway and utilize retrograde pathway for intracellular transport. In addition, the enhanced villi absorption in situ and oral liver distribution in vivo were also observed compared to PLGA@F127 NPs. Moreover, insulin-loaded PLGA@PPP4K NPs as an oral delivery application for diabetes induce a fine hypoglycemic response in diabetic rats after oral administration. The results of this study demonstrated that zwitterionic Pluronic analogs-coated NPs might provide a new perspective for zwitterionic materials application as well as oral delivery of biotherapeutics.

Surface design of nanocarriers: Key to more efficient oral drug delivery systems

As nanocarriers (NCs) can improve the solubility of drugs, prevent their degradation by gastrointestinal (GI) enzymes and promote their transport across the mucus gel layer and absorption membrane, the oral bioavailability of these drugs can be substantially enhanced. All these properties of NCs including self-emulsifying drug delivery systems (SEDDS), solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), liposomes, polymeric nanoparticles, inorganic nanoparticles and polymeric micelles depend mainly on their surface chemistry. In particular, interaction with food, digestive enzymes, bile salts and electrolytes, diffusion behaviour across the mucus gel layer and fate on the absorption membrane are determined by their surface. Bioinert surfaces limiting interactions with gastrointestinal fluid and content as well as with mucus, adhesive surfaces providing an intimate contact with the GI mucosa and absorption enhancing surfaces can be designed. Furthermore, charge converting surfaces shifting their zeta potential from negative to positive directly at the absorption membrane and surfaces providing a targeted drug release are advantageous. In addition to these passive surfaces, even active surfaces cleaving mucus glycoproteins on their way through the mucus gel layer can be created. Within this review, we provide an overview on these different surfaces and discuss their impact on the performance of NCs in the GI tract.

Oral Delivery of siRNA Using Fluorinated, Small-Sized Nanocapsules toward Anti-Inflammation Treatment

Oral delivery of small interfering RNA (siRNA) provides a promising paradigm for treating diseases that require regular injections. However, the multiple gastrointestinal (GI) and systemic barriers often lead to inefficient oral absorption and low bioavailability of siRNA. Technologies that can overcome these barriers are still lacking, which hinders the clinical potential of orally delivered siRNA. Herein, small-sized, fluorinated nanocapsules (F-NCs) are developed to mediate efficient oral delivery of tumor necrosis factor α (TNF-α) siRNA for anti-inflammation treatment. The NCs possess a disulfide-cross-linked shell structure, thus featuring robust stability in the GI tract. Because of their small size (≈30 nm) and fluorocarbon-assisted repelling of mucin adsorption, the best-performing F₃ -NCs show excellent mucus penetration and intestinal transport capabilities without impairing the intestinal tight junction, conferring the oral bioavailability of 20.4% in relative to intravenous injection. The disulfide cross-linker can be cleaved inside target cells, causing NCs dissociation and siRNA release to potentiate the TNF-α silencing efficiency. In murine models of acute and chronic inflammation, orally delivered F₃ -NCs provoke efficient TNF-α silencing and pronounced anti-inflammatory efficacies. This study therefore provides a transformative strategy for oral siRNA delivery, and will render promising utilities for anti-inflammation treatment.

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.

Mucus-penetrating dendritic mesoporous silica nanoparticle loading drug nanocrystal clusters to enhance permeation and intestinal absorption

Multiple gastrointestinal barriers (mucus clearance and epithelium barrier) are the main challenges in the oral administration of nanocarriers. To achieve efficient mucus penetration and epithelial absorption, a novel strategy based on mesoporous silica nanoparticles with dendritic superstructure, hydrophilicity, and nearly neutral-charged modification was designed. The mPEG covalently grafted dendritic mesoporous silica nanoparticles (mPEG-DMSNs) had a particle size of about 200 nm and a loading capacity of up to 50% andrographolide (AG) as a nanocrystal cluster in the mesoporous structure. This dual strategy of combining with the surface topography structure and hydrophilic modification maintained a high mucus permeability and showed an increase in cell absorption. The mPEG-DMSN formulation also exhibited effective transepithelial transport and intestinal tract distribution. The pharmacokinetics study demonstrated that compared with other AG formulations, the andrographolide nanocrystals-loaded mPEG-DMSN (AG@mPEG-DMSN) exhibited much higher bioavailability. Also, AG@mPEG-DMSN could significantly improve the in vitro and in vivo anti-inflammatory efficacy of AG. In summary, mPEG-DMSN offers an interesting strategy to overcome the mucus clearance and epithelium barriers of the gastrointestinal tract.

Hypoxia-Triggered Bioreduction of Poly(N-oxide)-Drug Conjugates Enhances Tumor Penetration and Antitumor Efficacy

PEGylation prolongs the blood circulation time of drugs; however, it simultaneously reduces the tumor penetration of drugs due to the nonfouling function and bulky hydrodynamic volume of PEG, leading to unsatisfactory outcomes in the treatment of solid tumors. Herein, we report the in situ growth of a bioreducible polymer of poly(N-oxide) from an important protein drug of interferon alpha (IFN) to generate site-specific IFN-poly(N-oxide) conjugates with higher bioactivity than a clinically used PEGylated IFN of PEGASYS. An IFN-poly(N-oxide) conjugate is screened out to have a circulating half-life as long as 51 h, which is similar to that of PEGASYS but 96-fold greater than that of IFN. However, the conjugate greatly outperforms PEGASYS and IFN in tumor penetration and antitumor efficacy in mice bearing melanoma. This enhanced tumor penetration is ascribed to the adsorption-mediated transcytosis of the conjugate whose poly(N-oxide) is biologically reduced into poly(tertiary amine), under hypoxia, which can be further protonated in the acidic tumor microenvironment. These novel findings demonstrate that poly(N-oxide)s are not only long-circulating but also bioreducible under hypoxia and are of great promise as next-generation carriers to deliver drugs into the interior of solid tumors to enhance their antitumor efficacy.

Determination of the critical micelle concentration of surfactants using fluorescence strategies

The increasing importance of surfactants in various fields has led to growing interest in the comprehensive characterization of surfactants. The critical micelle concentration (CMC), the most fundamental property of surfactants, is a parameter that must be measured. In particular, with the continuous expansion of the molecular structure of surfactants, numerous novel amphiphilic molecules have been developed that are capable of forming ordered aggregates in various solvent systems. Fluorescence spectroscopy, based on the differences in fluorescence intensity and wavelength of the fluorescent probe in the solvent phase and micellar phase, can sensitively detect the CMC of surfactants. This review aims to summarize the various fluorescence methods used to determine the CMC, including aggregation-induced emission (AIE), excimer formation, intramolecular charge transfer (ICT), and other miscellaneous strategies. The difficulties and limitations in the CMC determination process are also described. Further suggestions are provided to guide the existing fluorescence probes and the corresponding fluorescence methods to detect critical aggregation concentrations of amphiphilic molecules.

Nanotechnology strategies for hepatocellular carcinoma diagnosis and treatment

Hepatocellular carcinoma (HCC) is a common malignancy threatening human health, and existing diagnostic and therapeutic techniques are facing great challenges. In the last decade or so, nanotechnology has been developed and improved for tumor diagnosis and treatment. For example, nano-intravenous injections have been approved for malignant perivascular epithelioid cell tumors. This article provides a comprehensive review of the applications of nanotechnology in HCC in recent years: (I) in radiological imaging, magnetic resonance imaging (MRI), fluorescence imaging (FMI) and multimodality imaging. (II) For diagnostic applications in HCC serum markers. (III) As embolic agents in transarterial chemoembolization (TACE) or directly as therapeutic drugs. (IV) For application in photothermal therapy and photodynamic therapy. (V) As carriers of chemotherapeutic drugs, targeted drugs, and natural plant drugs. (VI) For application in gene and immunotherapy. Compared with the traditional methods for diagnosis and treatment of HCC, nanoparticles have high sensitivity, reduce drug toxicity and have a long duration of action, and can also be combined with photothermal and photodynamic multimodal combination therapy. These summaries provide insights for the further development of nanotechnology applications in HCC.

Oral Nanomotor-Enabled Mucus Traverse and Tumor Penetration for Targeted Chemo-Sono-Immunotherapy against Colon Cancer

The therapeutic outcomes of oral nanomedicines against colon cancer are heavily compromised by their lack of specific penetration into the internal tumor, favorable anti-tumor activity, and activation of anti-tumor immunity. Herein, hydrogen peroxide (H₂ O₂ )/ultrasound (US)-driven mesoporous manganese oxide (MnO_x )-based nanomotors are constructed by loading mitochondrial sonosensitizers into their mesoporous channels and orderly dual-functionalizing their surface with silk fibroin and chondroitin sulfate. The locomotory activities and tumor-targeting capacities of the resultant nanomotors (CS-ID@NMs) are greatly improved in the presence of H₂ O₂ and US irradiation, inducing efficient mucus-traversing and deep tumor penetration. The excess H₂ O₂ in the tumor microenvironment (TME) is decomposed into hydroxyl radicals and oxygen by an Mn²⁺ -mediated Fenton-like reaction, and the produced oxygen participates in sonodynamic therapy (SDT), yielding abundant singlet oxygen. The combined Mn²⁺ -mediated chemodynamic therapy and SDT cause effective ferropotosis of tumor cells and accelerate the release of tumor antigens. Importantly, animal experiments reveal that the treatment of combining oral hydrogel (chitosan/alginate)-embedding CS-ID@NMs and immune checkpoint inhibitors can simultaneously suppress the growth of primary and distal tumors through direct killing, reversion of immunosuppressive TME, and potentiation of systemic anti-tumor immunity, demonstrating that the CS-ID@NM-based platform is a robust oral system for synergistic treatment of colon cancer.

A dual-channel fluorescent ratio probe with hypoxia targeting and hypoxia activation capacity for tumour imaging

Efficient hypoxia diagnosis is a great challenge for nearly all solid tumours due to the operability, permeability and specificity. Although some inspiring approaches have been explored to date, it is...