Hybrid drug nanocrystals

Emodin nanocrystals enhanced mucus penetration and ameliorated bleomycin-induced pulmonary fibrosis by pulmonary delivery

Pulmonary fibrosis (PF) is a progressive interstitial disease characterised by extracellular matrix deposition and destruction of lung tissue structure. Emodin (Emo) is a natural active compound with anti-inflammatory and antioxidant properties. The initiation of PF is prevented by reducing oxidative stress-induced damage to alveolar epithelial cells." to meet the word count requirement. However, Emo is featured low water solubility, a rapid metabolic rate and low oral bioavailability, which limit its application in the treatment of PF. Therefore, this study formulated emodin as nanocrystals (Emo-NCs) and delivered Emo directly to the lesion site via pulmonary delivery to enhance drug efficacy. The Emo-NCs exhibited a square crystal structure with particle sizes suitable for pulmonary absorption and an appropriate polydispersity index. They released 99.38% over 48 h and significantly improved permeability efficiency in simulated pulmonary mucus. The ability of Emo-NCs to inhibit abnormal fibroblast proliferation and oxidative damage was significantly enhanced compared with Emo. In contrast to the BLM group, the inflammatory cells in the lung tissue sections of the Emo-NCs group were significantly reduced, the alveolar structure was largely restored, and no evident collagen fibre deposition was observed. In summary, Emo-NCs could serve as a viable delivery system for site-specific treatment of PF.

Design and delivery effect of prolonged-retention dexamethasone and tacrolimus microcrystals eye drops

The improvement of drug solubility is essential for enhancing drug absorption of eye drops, particularly for poorly soluble drugs. In this study, drug crystallization techniques were utilized to synthesize dexamethasone microcrystals (DES MCs) and tacrolimus microcrystals (TAM MCs). To further enhance the retention of the MCs, DES MCs@(PEI/HA)3 and TAM MCs@(PEI/HA)3 were prepared by the alternate deposition of polyethyleneimine (PEI) and hyaluronic acid (HA) on the surface of the MCs through electrostatic adsorption. The sustained release effect of TAM MCs@(PEI/HA)3, resulting from enhanced solubility through micro-crystallization, was confirmed via solubility measurements and in vitro release studies. Similarly, DES MCs@(PEI/HA)3 exhibited comparable sustained release properties. Subsequently, the hydrophobicity, safety, and efficacy of DES MCs@(PEI/HA)3 and TAM MCs@(PEI/HA)3 were investigated through the in vitro and in vivo experiments. Notably, TAM MCs@(PEI/HA)3 demonstrated superior efficacy over commercially available TALYMUS®, enabling a once-daily dosing regimen. In conclusion, microcrystal preparation exhibited a more significant impact on the delivery of tacrolimus compared to dexamethasone. The TAM MCs@(PEI/HA)3 microcrystals suspension eye drops prepared using the layer-by-layer self-assembly technique, offer a promising strategy for enhancing the solubility of poorly soluble drugs and ocular drug delivery.

The self-fluorescence verification and intracellular imaging of nanocrystals imbedded with aggregation-induced emission luminescent materials

Understanding cellular uptake and intracellular dissolution of drug nanocrystals is necessary. Due to their superior sensitivity, luminescent materials with aggregation-induced emission (AIE) are embedded into drug nanocrystals (hybrid nanocrystals) as a good strategy for tracking intact nanocrystals in cells. However, AIE materials are strongly hydrophobic and tend to self-aggregate, generating fluorescent interference. To exclusively mark nanocrystals, AIE materials must be embedded in nanocrystals and remain soluble when released from dissolved nanocrystals. In this study, cyclosporin A (CsA) nanocrystals (CsA/THPE NCs) embedded with tetrakis(4-hydroxyphenyl)ethylene (THPE) possessing AIE properties were prepared. The self-fluorescence of CsA/THPE NCs was collectively corroborated by scanning electron microscopy, powder X-ray diffraction, fluorescence microscopy, and dissolution experiments. During the dissolution test, CsA/THPE NCs showed a certain degree of slow-release property. Cellular uptake studies were conducted with Caco-2 cells and characterized by confocal microscopy, flow cytometry, and quantitative analyses. The intact nanocrystals could be directly taken up by cells. The cellular uptake was found to be concentration- and time-dependent. Based on the above experimental results, hybrid nanocrystals integrated with AIE materials were verified to have specific self-fluorescence. Additionally, the dissolution rate of nanocrystals can be adjusted by physically embedding them with other materials.

A review on polysaccharide-based tumor targeted drug nanodelivery systems

The tumor-targeted drug delivery system (TTDNS) uses nanocarriers to transport chemotherapeutic agents to target tumor cells or tissues precisely. This innovative approach considerably increases the effective concentration of these drugs at the tumor site, thereby enhancing their therapeutic efficacy. Many chemotherapeutic agents face challenges, such as low bioavailability, high cytotoxicity, and inadequate drug resistance. To address these obstacles, TTDNS comprising natural polysaccharides have gained increasing popularity in the field of nanotechnology owing to their ability to improve safety, bioavailability, and biocompatibility while reducing toxicity. In addition, it enhances permeability and allows for controlled drug delivery and release. This review focuses on the sources of natural polysaccharides and their direct and indirect mechanisms of anti-tumor activity. We also explored the preparation of various polysaccharide-based nanocarriers, including nanoparticles, nanoemulsions, nanohydrogels, nanoliposomes, nanocapsules, nanomicelles, nanocrystals, and nanofibers. Furthermore, this review delves into the versatile applications of polysaccharide-based nanocarriers, elucidating their capabilities for in vivo targeting, controlled release, and responsiveness to endogenous and exogenous stimuli, such as pH, reactive oxygen species, glutathione, light, ultrasound, and magnetic fields. This sophisticated design substantially enhances the chemotherapeutic efficacy of the encapsulated drugs at tumor sites and provides a basis for preclinical and clinical research. However, the in vivo stability, drug loading, and permeability of these preparations into tumor tissues still need to be improved. Most of the currently developed biomarker-sensitive polysaccharide nanocarriers are still in the laboratory stage, more innovative delivery mechanisms and clinical studies are needed to develop commercial nanocarriers for medical use.

Pure drug nanomedicines - where we are?

Pure drug nanomedicines (PDNs) encompass active pharmaceutical ingredients (APIs), including macromolecules, biological compounds, and functional components. They overcome research barriers and conversion thresholds associated with nanocarriers, offering advantages such as high drug loading capacity, synergistic treatment effects, and environmentally friendly production methods. This review provides a comprehensive overview of the latest advancements in PDNs, focusing on their essential components, design theories, and manufacturing techniques. The physicochemical properties and in vivo behaviors of PDNs are thoroughly analyzed to gain an in-depth understanding of their systematic characteristics. The review introduces currently approved PDN products and further explores the opportunities and challenges in expanding their depth and breadth of application. Drug nanocrystals, drug-drug cocrystals (DDCs), antibody-drug conjugates (ADCs), and nanobodies represent the successful commercialization and widespread utilization of PDNs across various disease domains. Self-assembled pure drug nanoparticles (SAPDNPs), a next-generation product, still require extensive translational research. Challenges persist in transitioning from laboratory-scale production to mass manufacturing and overcoming the conversion threshold from laboratory findings to clinical applications.

A Library of Polyphenol-Amino Acid Condensates for High-Throughput Continuous Flow Production of Nanomedicines with Ultra-High Drug Loading

Synthesizing high drug-loading nanomedicines remains a formidable challenge, and achieving universally applicable, continuous, large-scale engineered production of such nanomedicines presents even greater difficulties. This study presents a scalable library of polyphenol-amino acid condensates. By selecting amino acids, the library enables precise customization of key properties, such as carrier capacity, bioactivity, and other critical attributes, offering a versatile range of options for various application scenarios. Leveraging the properties of solvent-mediated disassembly and reassembly of condensates achieved an ultra-high drug loading of 86% for paclitaxel. For a range of poorly soluble molecules, the drug loading capacity exceeded 50%, indicating broad applicability. Furthermore, employing a continuous microfluidic device, the production rate can reach 5 mL min-1 (36 g per day), with the nanoparticle size precisely tunable and a polydispersity index (PDI) below 0.2. The polyphenol-based carrier demonstrates efficient cellular uptake and, in three distinct animal models, has been shown to enhance the therapeutic efficacy of paclitaxel without significant side effects. This study presents a streamlined, efficient, and scalable approach using microfluidics to produce nanomedicines with ultra-high drug loading, offering a promising strategy for the nanoformulation of poorly soluble drugs.

Polymer-Mediated Delivery of Amphotericin B for Fungal Infections

Invasive fungal infections have been an increasingly global issue with high mortality. Amphotericin B (AmB), as the "gold standard" antifungal drug, has broad-spectrum antifungal activity and low clinical resistance. Therefore, AmB is the most commonly used polyene antibiotic for the treatment of invasive fungal infections. However, the serious side effects as well as the low bioavailability of AmB strongly restrict its clinical applications. Polymer, with its diversified molecular design, is widely used in drug delivery in the form of polymeric prodrugs, nanoparticles, hydrogels, etc. Therefore, polymers hold great promise for the delivery of AmB in treating fungal infections. This review summarizes recent advances in polymer-based delivery systems of AmB for the treatment of fungal infections, including polymer-AmB conjugates, nanotechnology-based polymeric delivery systems, hydrogels, and polymeric microneedles. Taking advantage of polymer-based delivery strategies, special attention is paid to reducing the side effects and improving the bioavailability of AmB for safe and effective antifungal therapy. Finally, the limitations and possible future directions of polymer-based AmB delivery systems are discussed.

Advanced Carriers for Precise Delivery and Therapeutic Mechanisms of Traditional Chinese Medicines: Integrating Spatial Multi-Omics and Delivery Visualization

The complex composition of traditional Chinese medicines (TCMs) has posed challenges for in-depth study and global application, despite their abundance of bioactive compounds that make them valuable resources for disease treatment. To overcome these obstacles, it is essential to modernize TCMs by focusing on precise disease treatment. This involves elucidating the structure-activity relationships within their complex compositions, ensuring accurate in vivo delivery, and monitoring the delivery process. This review discusses the research progress of TCMs in precision disease treatment from three perspectives: spatial multi-omics technology for precision therapeutic activity, carrier systems for precise in vivo delivery, and medical imaging technology for visualizing the delivery process. The aim is to establish a novel research paradigm that advances the precision therapy of TCMs.

Unraveling the Impact of Stabilizers on Nanocrystal Preparation and Oral Absorption: A Case Study of Poorly Soluble Andrographolide

Drug nanocrystal engineering is an attractive pharmaceutical approach to enhancing the oral bioavailability of poorly soluble drugs. The mechanism of drug nanocrystal stabilization, however, is unclear. Here we developed andrographolide nanocrystals (AG-NCs) with various nonionic surfactants (Pluronic-F127, TPGS, or Brij-S20). We detected AG micelles (AG-MCs) at an andrographolide to nonionic surfactant ratio of 10:10 (w/w) and poor AG-NC size stability. We thus quantified the unbound Pluronic-F127 in AG-NCs and found that the proposed instantaneous binding rate sharply declined with increasing Pluronic-F127 input. We determined that the saturation dose of TPGS on AG-NCs was approximately 10:10 (w/w) and recommend it as a key criterion for nanocrystal formulation. Although AG-NCs exhibited a marginally faster dissolution rate, they possessed better mucus-penetrating and transmembrane transport capacities and significantly enhanced oral absorption compared to AG-MCs. These findings give insights into the impact of a stabilizer during the preparation process and the oral absorption of drug nanocrystals.

Subconjunctival injection of microcrystalline prodrug of dexamethasone for long-acting anti-inflammation after phacoemulsification surgery

Long-acting injectable formulations of dexamethasone with minimal invasiveness are highly desired to manage chronic ocular inflammatory conditions. Here, we applied microcrystals (MCs) of a hydrophobic acetone-based ketal-linked prodrug of dexamethasone (SKD) to treat postoperative ocular inflammation. We compared the efficacy and safety of SKD MCs through subconjunctival (SC) injection with that of Maxidex (a topical suspension of dexamethasone MCs) through SC injection and eye drops in the phacoemulsification combined with intraocular lens implantation (Phaco-IOL) rabbit model. In Phaco-IOL rabbit eyes, a single SC injection of SKD MCs (0.4 mg dexamethasone equiv.) showed anti-inflammatory effects comparable to Maxidex eye drops and completely alleviated the inflammation within 28 days, while an SC injection of Maxidex at the same dose only provided anti-inflammatory effects for 7 days. The study on the dose-dependent anti-inflammatory effects of SKD MCs showed no significant difference in anti-inflammatory effects for the high dosage (0.8 mg dexamethasone equiv.) and the low dosage (0.4 mg dexamethasone equiv.) in 28 days. Nevertheless, systematic drug distribution of SKD MCs and Maxidex in normal rabbits after SC injection demonstrates that the drug concentration in conjunctiva was higher for the high dosage and that a considerable amount of prodrug and dexamethasone could still be detected in the cornea and iris-ciliary body at least 84 days for SKD MCs at high dosage. Furthermore, no persistent elevated intraocular pressure and abnormality in retinal structure and thickness were observed, confirming the excellent safety of long-acting SKD MCs post-SC injection. Our findings provide valuable insights into using prodrug-based MCs for treating ocular postoperative inflammation, and the detailed drug distribution analysis would promote the clinical translation of these MCs in ocular diseases.

Tea Saponins: a Novel Stabilizer for Enhancing the Oral Bioavailability of Albendazole Nanocrystals

Albendazole serves as a broad-spectrum anthelmintic medication for treating hydatid cysts and neurocysticercosis. However, its therapeutic effectiveness is limited by poor solubility. Nanocrystals offer a promising technology to address this limitation by enhancing drug solubility. The objective of this study is to evaluate an effective stabilizer for creating an albendazole nanocrystal formulation to improve oral absorption. Among different surfactants and polymers examined, tea saponins were used as the stabilizer to develop a nanosuspension with the particle size of 180 nm through a wet grinding approach. The physical characteristics of the nanocrystals were assessed using SEM, DSC, and XRPD. The nanocrystals significantly enhanced solubility by 2.9-2602 fold in different media and showed significant enhancement in dissolution rate compared to albendazole crystals in both pH 1.0 and pH 6.8 medium. Everted gut sacs experiments demonstrated that the nanocrystals increased Papp by 3.60-fold in duodenum, 3.76-fold in jejunum, 3.71-fold in ileum, and 5.26-fold in colon, respectively. Furthermore, pharmacokinetic studies revealed that the nanocrystals significantly enhanced oral bioavailability, resulting in a 4.65-fold increase in plasma AUC0-t value of albendazole sulfoxide (the primary active metabolite of albendazole) compared to the albendazole group. The present data indicates that tea saponins are potential natural stabilizers for preparing nanocrystals with enhanced oral bioavailability for insoluble drugs.

In vitro and in vivo performance of amorphous solid dispersions of ursolic acid as a function of polymer type and excipient addition

OBJECTIVES

The objective of this research was to enhance the bioavailability of ursolic acid (UA) by preparing multielement amorphous solid dispersion (ASD) systems comprising excipients.

METHODS

The ASDs were prepared via the solvent evaporation method, characterized by a range of techniques, and investigated with respect to permeability of human colorectal adenocarcinoma cell line (Caco-2) cells monolayers and pharmacokinetics, with comparisons made to the physical mixture and the pure drug.

KEY FINDINGS

The (UA-choline)-Polyethylcaprolactam-polyvinyl acetate-polyethylene glycol grafted copolymer (Soluplus)-Vitamin E polyethylene glycol succinate (TPGS) ASD demonstrated superior dissolution properties compared to the corresponding binary solid dispersions and ternary solid dispersions (P< .05). The permeability studies of Caco-2 cell monolayers revealed that the ASD exhibited moderate permeability, with an efflux rate that was significantly lower than that of the UA raw material (P< .05). Pharmacokinetic studies in rats demonstrated that the oral bioavailability of the ASD was 19.0 times higher than that of UA (P< .01).

CONCLUSIONS

The research indicated that the multielement ASD could be employed as an efficacious drug delivery system for UA. Furthermore, the Soluplus/TPGS/choline combination represents a promising candidate for the fabrication of ASDs that can load weakly acidic and poorly soluble drugs.

Drug nanocrystals: Surface engineering and its applications in targeted delivery

Drug nanocrystals have received significant attention in drug development due to their enhanced dissolution rate and improved water solubility, making them effective in overcoming issues related to drug hydrophobicity, thereby improving drug bioavailability and treatment effectiveness. Recent advances in preparation techniques have facilitated research on drug surface properties, leading to valuable surface engineering strategies. Surface modification can stabilize drug nanocrystals, making them suitable for versatile drug delivery platforms. Functionalized ligands further enhance the potential for targeted delivery, enabling precision medicine. This review focuses on the surface engineering of drug nanocrystals, discussing various preparation methods, surface ligand design strategies, and their applications in targeted drug delivery, especially for cancer treatments. Finally, challenges and future directions are also discussed to promote the development of drug nanocrystals. The surface engineering of drug nanocrystals promises new opportunities for treating complex and chronic diseases while broadening the application of drug delivery systems.

Drug self-delivery systems: A comprehensive review on small molecule nanodrugs

Drug self-delivery systems are nanostructures composed of a drug as the main structural unit, having the ability of intracellular trafficking with no additional carrier. In these systems, the drug itself undertakes the functional and structural roles; thereby, the ancillary role of excipients and carrier-related limitations are circumvented and therapeutic effect is achieved at a much lower dose. Such advantages -which are mainly but not exclusively beneficial in cancer treatment- have recently led to an upsurge of research on these systems. Subsequently, various terminologies were utilized to describe them, referring to the same concept with different words. However, not all the systems developed based on the self-delivery approach are introduced using one of these keywords. Using a scoping strategy, this review aims to encompass the systems that have been developed as yet -inspired by the concept of self-delivery- and classify them in a coherent taxonomy. Two main groups are introduced based on the type of building blocks: small molecule-based nanomedicines and self-assembling hybrid prodrugs. Due to the diversity, covering the whole gamut of topics is beyond the scope of a single article, and, inevitably, the latter is just briefly introduced here, whereas the features of the former group are meticulously presented. Depending on whether the drug is merely a carrier for itself or carries a second drug as cargo, two classes of small molecule-based nanomedicines are defined (i.e., pure nanodrugs and carrier-mimicking systems, respectively), each having sub-branches. After introducing each branch and giving some examples, possible strategies for designing each particular system are visually displayed. The resultant mind map can create a macro view of the taken path and its prospects, give a profound insight into opportunities, spark new ideas, and facilitate overcoming obstacles. Taken together, one can foresee a brilliant future for self-delivery systems as a pioneering candidate for the next generation of drug delivery systems.

Transforming Healthcare with Nanomedicine: A SWOT Analysis of Drug Delivery Innovation

Objective

Nanomedicine represents a transformative approach in biomedical applications. This study aims to delineate the application of nanomedicine in the biomedical field through the strengths, weaknesses, opportunities, and threats (SWOT) analysis to evaluate its efficacy and potential in clinical applications.

Methods

The SWOT analysis framework was employed to systematically review and assess the internal strengths and weaknesses, along with external opportunities and threats of nanomedicine. This method provides a balanced consideration of the potential benefits and challenges.

Results

Findings from the SWOT analysis indicate that nanomedicine presents significant potential in drug delivery, diagnostic imaging, and tissue engineering. Nonetheless, it faces substantial hurdles such as safety issues, environmental concerns, and high development costs. Critical areas for development were identified, particularly concerning its therapeutic potential and the uncertainties surrounding long-term effects.

Conclusion

Nanomedicine holds substantial promise in driving medical innovation. However, successful clinical translation requires addressing safety, cost, and regulatory challenges. Interdisciplinary collaboration and comprehensive strategic planning are crucial for the safe and effective application of nanomedicine.

In vivo deposition of poorly soluble drugs

Administered drug molecules, whether dissolved or solubilized, have the potential to precipitate and accumulate as solid forms in tissues and cells within the body. This phase transition can significantly impact the pharmacokinetics of treatment. It is thus crucial to gain an understanding of how drug solubility/permeability, drug formulations and routes of administration affect in vivo behaviors of drug deposition. This review examines literature reports on the drug deposition in tissues and cells of poorly water-soluble drugs, as well as underlying physical mechanisms that lead to precipitation. Our work particularly highlights drug deposition in macrophages and the subcellular fate of precipitated drugs. We also propose a tissue permeability-based classification framework to evaluate precipitation potentials of poorly soluble drugs in major organs and tissues. The impact on pharmacokinetics is further discussed and needs to be considered in developing drug delivery systems. Finally, bioimaging techniques that are used to examine aggregated states and the intracellular trafficking of absorbed drugs are summarized.

Local anesthetic delivery systems for the management of postoperative pain

Postoperative pain (POP) is a major clinical challenge. Local anesthetics (LAs), including amide-type LAs, ester-type LAs, and other potential ion-channel blockers, are emerging as drugs for POP management because of their effectiveness and affordability. However, LAs typically exhibit short durations of action and prolonging the duration by increasing their dosage or concentration may increase the risk of motor block or systemic local anesthetic toxicity. In addition, techniques using LAs, such as intrathecal infusion, require professional operation and are prone to catheter displacement, dislodgement, infection, and nerve damage. With the development of materials science and nanotechnology, various LAs delivery systems have been developed to compensate for these disadvantages. Numerous delivery systems have been designed to continuously release a safe dose in a single administration to ensure minimal systemic toxicity and prolong pain relief. LAs delivery systems can also be designed to control the duration and intensity of analgesia according to changes in the external trigger conditions, achieve on-demand analgesia, and significantly improve pain relief and patient satisfaction. In this review, we summarize POP pathways, animal models and methods for POP testing, and highlight LAs delivery systems for POP management. STATEMENT OF SIGNIFICANCE: Postoperative pain (POP) is a major clinical challenge. Local anesthetics (LAs) are emerging as drugs for POP management because of their effectiveness and affordability. However, they exhibit short durations and toxicity. Various LAs delivery systems have been developed to compensate for these disadvantages. They have been designed to continuously release a safe dose in a single administration to ensure minimal toxicity and prolong pain relief. LAs delivery systems can also be designed to control the duration and intensity of analgesia to achieve on-demand analgesia, and significantly improve pain relief and patient satisfaction. In this paper, we summarize POP pathways, animal models, and methods for POP testing and highlight LAs delivery systems for POP management.

Niclosamide: A career builder

My contribution to honoring Professor Kinam Park celebrates and resonates with his scholarly career in drug delivery, his commitment to encouraging the next generation(s), and his efforts to keep us focused on clinically effective formulations. To do this I take as my example, niclosamide, a small molecule protonophore that, uniquely, can "target" all cell membranes, both plasma and organelle. As such, it acts upstream of many cell pathways and so has the potential to affect many of the essential events that a cell, and particularly a diseased cell or other entities like a virus, use to stay alive and prosper. Literature shows that it has so far been discovered to positively influence (at least): cancer, bacterial and viral infection, metabolic diseases such as Type II diabetes, NASH and NAFLD, artery constriction, endometriosis, neuropathic pain, rheumatoid arthritis, sclerodermatous graft-versus-host disease, systemic sclerosis, Parkinson's, and COPD. With such a fundamental action and broad-spectrum activity, I believe that studying niclosamide in all its manifestations, discovering if and to what extent it can contribute positively to disease control (and also where it can't), formulating it as effective therapeutics, and testing them in preclinical and clinical trials is a career builder for our next generation(s). The article is divided into two parts: Part I introduces niclosamide and other proton shunts mainly in cancer and viral infections and reviews an exponentially growing literature with some concepts and physicochemical properties that lead to its proton shunt mechanism. Part II focuses on repurposing by reformulation of niclosamide. I give two examples of "carrier-free formulations", - one for cancer (as a prodrug therapeutic of niclosamide stearate for i.v. and other administration routes, exemplified by our recent work on Osteosarcoma in mice and canine patients), and the other as a niclosamide solution formulation (that could provide the basis for a preventative nasal spray and early treatment option for COVID19 and other respiratory virus infections). My goal is to excite and enthuse, encourage, and motivate all involved in the drug development and testing process in academia, institutes, and industry, to learn more about this interesting molecule and others like it. To enable such endeavors, I give many proposed ideas throughout the document, that have been stimulated and inspired by gaps in the literature, urgent needs in disease, and new studies arising from our own work. The hope is that, by reading through this document and studying the suggested topics and references, the drug delivery and development community will continue our lineage and benefit from our legacy to achieve niclosamide's potential as an effective contributor to the treatment and control of many diseases and conditions.

Nanocrystal technologies in biomedical science: From the bench to the clinic

The pharmaceutical industry is grappling with a pressing crisis in drug development characterized by soaring R&D costs, setbacks in blockbuster drug development due to poor aqueous solubility, and patent-related limitations on newly approved molecules. To combat these challenges, diverse strategies have emerged to enhance the solubility and dissolution rates of Biopharmaceutics Classification System (BCS) II and IV drug molecules. Enter drug nanocrystals, a revolutionary nanotechnology-driven, carrier-free colloidal drug delivery system. This review provides a comprehensive insight into nanocrystal strategies, stabilizer selection criteria, preparation methods, advanced characterization techniques, the evolving nanocrystal technological landscape, current market options, and exciting clinical prospects for reshaping the future of pharmaceuticals.

Recent advances in nanocrystal-based technologies applied for ocular drug delivery

INTRODUCTION

The intricate physiological barriers of the eye and the limited volume of eye drops impede efficient delivery of poorly water-soluble drugs. In the last decade, nanocrystals have emerged as versatile drug delivery systems in various administration routes from bench to bedside. The unique superiorities of nanocrystals, mainly embodied in high drug-loading capacity, good mucosal adhesion and penetration, and greatly improved drug solubility, reveal a promising prospect for ocular delivery of poorly water-soluble drugs.

AREAS COVERED

This article focuses on the ophthalmic nanocrystal technologies and products that are in the literature, clinical trials, and even on the market. The recent research progress in the preparation, ocular application, and absorption of nanocrystals are highlighted, and the pros and cons of nanocrystals in overcoming the physiological barriers of the eye are also summarized.

EXPERT OPINION

Nanocrystals have demonstrated success as glucocorticoid eye drops in the treatment of anterior segment diseases. However, the thermodynamic stability of nanocrystals remains the major challenge in product development. New technologies for efficiently optimizing stabilizers and sterilization processes are still expected. Strategies to confer more diverse functions via surface modification are also worth exploration to improve the potential of nanocrystals in delivering poorly water-soluble drugs to posterior segment of the eye.

Pulmonary endothelium-targeted nanoassembly of indomethacin and superoxide dismutase relieves lung inflammation

Lung inflammation is an essential inducer of various diseases and is closely related to pulmonary-endothelium dysfunction. Herein, we propose a pulmonary endothelium-targeted codelivery system of anti-inflammatory indomethacin (IND) and antioxidant superoxide dismutase (SOD) by assembling the biopharmaceutical SOD onto the "vector" of rod-like pure IND crystals, followed by coating with anti-ICAM-1 antibody (Ab) for targeting endothelial cells. The codelivery system has a 237 nm diameter in length and extremely high drug loading of 39% IND and 2.3% SOD. Pharmacokinetics and biodistribution studies demonstrate the extended blood circulation and the strong pulmonary accumulation of the system after intravenous injection in the lipopolysaccharide (LPS)-induced inflammatory murine model. Particularly, the system allows a robust capacity to target pulmonary endothelium mostly due to the rod-shape and Ab coating effect. In vitro, the preparation shows the synergistic anti-inflammatory and antioxidant effects in LPS-activated endothelial cells. In vivo, the preparation exhibits superior pharmacodynamic efficacy revealed by significantly downregulating the inflammatory/oxidative stress markers, such as TNF-α, IL-6, COX-2, and reactive oxygen species (ROS), in the lungs. In conclusion, the codelivery system based on rod-like pure crystals could well target the pulmonary endothelium and effectively alleviate lung inflammation. The study offers a promising approach to combat pulmonary endothelium-associated diseases.

Application of nanotechnology in bladder cancer diagnosis and therapeutic drug delivery

Bladder cancer (BC) is one of the most common malignant tumors in the urinary system, and its high recurrence rate is a great economic burden to patients. Traditional diagnosis and treatment methods have the disadvantages of insufficient targeting, obvious side effects and low sensitivity, which seriously limit the accurate diagnosis and efficient treatment of BC. Due to their small size, easy surface modification, optical properties such as plasmon resonance, and surface enhanced Raman scattering, good electrical conductivity and photothermal conversion properties, nanomaterials have great potential application value in the realization of specific diagnosis and targeted therapy of BC. At present, the application of nanomaterials in the diagnosis and treatment of BC is attracting great attention and achieving rich research results. Therefore, this paper summarizes the recent research on nanomaterials in the diagnosis and treatment of BC, clarifies the existing advantages and disadvantages, and provides theoretical guidance for promoting the accurate diagnosis and efficient treatment of BC.

Intravenous nanocrystals: fabrication, solidification, in vivo fate, and applications for cancer therapy

INTRODUCTION

Intravenous nanocrystals (INCs) have shown intrinsic advantages in antitumor applications, particularly their properties of high drug loading, low toxicity, and controllable size. Therefore, it has a very bright application prospect as a drug delivery system.

AREAS COVERED

The ideal formulation design principles, fabrication, solidification, in vivo fate of INCs, the applications in drug delivery system (DDS) and the novel applications are covered in this review.

EXPERT OPINION

It is vital to select a suitable formulation and fabrication method to produce a stable and sterile INCs. Besides, the type of stabilizers and physical characteristics can also influence the in vivo fate of INCs, which is worthy of further studying. Based on wide researches about applications of INCs in cancer, biomimetic INCs are concerned increasingly for its favorable compatibility. The output of these studies suggested that INCs-based drug delivery could be a novel strategy for addressing the delivery of the drug that faces solubility, bioavailability, and toxicity problems.

Pickering Emulsions Enhance Oral Bioavailability of Curcumin Nanocrystals: The Effect of Oil Types

Nanocrystals (NCs) have the potential to enhance the oral bioavailability of Class IV drugs in the Biopharmaceutical Classification System (BCS) due to the absorption of the intact crystals. The performance is compromised by the dissolution of NCs. Drug NCs have recently been adopted as solid emulsifiers to prepare nanocrystal self-stabilized Pickering emulsions (NCSSPEs). They are advantageous in high drug loading and low side effects due to the specific drug loading mode and the absence of chemical surfactants. More importantly, NCSSPEs may further enhance the oral bioavailability of drug NCs by impeding their dissolution. This is especially true for BCS IV drugs. In this study, curcumin (CUR), a typical BCS IV drug, was adopted to prepare CUR-NCs stabilized Pickering emulsions using either indigestible (isopropyl palmitate, IPP) or digestible (soybean oil, SO) oils, i.e., IPP-PEs and SO-PEs. The optimized formulations were spheric with CUR-NCs adsorbed on the water/oil interface. The CUR concentration in the formulation reached 20 mg/mL, which was far beyond the solubility of CUR in IPP (158.06 ± 3.44 μg/g) or SO (124.19 ± 2.40 μg/g). Moreover, the Pickering emulsions enhanced the oral bioavailability of CUR-NCs, being 172.85% for IPP-PEs and 152.07% for SO-PEs. The digestibility of the oil phase affected the amounts of CUR-NCs that remained intact in lipolysis and, thus, the oral bioavailability. In conclusion, converting NCs into Pickering emulsions provides a novel strategy to enhance the oral bioavailability of CUR and BCS IV drugs.

Exploring the translocation behaviours in vivo of herpetrione amorphous nanoparticles via oral delivery

Nanotechnology has been a primary strategy to enhance oral bioavailability of poorly water soluble drugs. However, the limited information in vivo fate of impedes the development of nanoparticles via the oral delivery, especially the amorphous nanoparticles with high energy states are rarely reported. This study is to track the translocation of oral herpetrione amorphous nanoparticles (HPE-ANPs). We prepare amorphous particles (ANPs) of various sizes (200 nm and 450 nm), which are embedded with an aggregation-caused quenching (ACQ) dyes for tracking the intact nanoparticles. Nanoparticles remain in the gastrointestinal tract (GIT) for 8 h following oral administration, suggesting that most ANPs was mainly degraded or absorbed in the small intestine. Ex vivo imaging shows that the fluorescent signals are observed in the GIT and liver but not in other organs, which attributed to low absorption of integral nanoparticles. Besides, HPE-ANPs may be directly interact with GIT epithelia, and ileum provides better absorption than the jejunum. Cellular studies prove that integral HPE-ANPs can be taken up by enterocyte, while it penetrates cell monolayers only small amounts. In conclusion, we speculate that the drug in the form of integral nanoparticles and small molecules may be co-absorbed to improve bioavailability in vivo.

NIR light-activatable dissolving microneedle system for melanoma ablation enabled by a combination of ROS-responsive chemotherapy and phototherapy

BACKGROUND

As a consequence of the aggressive and recurrent nature of melanoma, repeated, multimodal treatments are often necessary to cure the disease. While microneedle (MN)-based transdermal drug delivery methods can allow drugs to avoid first-pass metabolism and overcome the stratum corneum barrier, the main challenges of these delivery methods entail the lack of controlled drug release/activation and effective imaging methods to guide the entire treatment process.

METHODS

To enable a transdermal delivery method with controllable drug release/activation and effective imaging guidance, we designed a near-infrared (NIR) photoactivatable, dissolving MN system comprising dissolvable polyvinylpyrrolidone MNs arrays (MN-pB/I) containing liposomes that were co-loaded with the photosensitizer indocyanine green (ICG) and the reactive oxygen species (ROS)-activatable prodrug of doxorubicin (pB-DOX).

RESULTS

After applying the MN patch to the tumor site, the liposomes concentrated in the needle tips were released into the tumor tissue and distributed evenly upon dissolution of the matrix to enable targeted delivery. Then, the ROS produced by ICG after exposure to NIR light performed photodynamic therapy and activated the pB-DOX for chemotherapy by cleaving the prodrug moiety and converting it to DOX. As a dye, ICG was also used to guide the treatment regimens and monitor the efficacy by fluorescence and photoacoustic imaging. The growth of the tumors in the MN-pB/I group were inhibited by 93.5%, while those were only partially inhibited in the control groups. Negligible treatment-induced side effects and cardiotoxicity were observed.

CONCLUSION

The MN-pB/I represents a multimodal, biocompatible theragnostic system with spatiotemporal control that was capable of ablating melanoma tumors after a single dose, providing a promising candidate for clinical melanoma therapy.

Albumin-Based Silibinin Nanocrystals Targeting Activated Hepatic Stellate Cells for Liver Fibrosis Therapy

Activated hepatic stellate cells (aHSCs) are critical during the development and progression of liver fibrosis. Once liver fibrosis occurs, aHSCs highly express secreted protein, acidic and rich in cysteine (SPARC), a typical albumin-binding protein. We designed a nano platform, silibinin albumin nanocrystals (SLB-HSA NCs), to target aHSCs for liver fibrosis therapy. The prepared SLB-HSA NCs showed uniform particle size distribution of approximately 60 nm with PDI < 0.15 and high loading efficiency up to 49.4%. Albumin coated on the surface of nanocrystals was demonstrated to increase cellular uptake by aHSCs through SPARC-mediated endocytosis. In addition, SLB-HSA NCs significantly improved the bioavailability compared with free SLB in pharmacokinetic study. Following tail-vein injection, SLB-HSA NCs were massively accumulated in the fibrotic liver and exhibited enhanced antifibrotic effects in hepatic fibrosis mice. Overall, our findings prove the great potential of SLB-HSA NCs in the targeted treatment of liver fibrosis.

Enhanced oral bioavailability from food protein nanoparticles: A mini review

The oral route is the most desirable drug administration path. The oral bioavailability is always compromised from the poor physicochemical and/or biopharmaceutical properties of the active pharmaceutical ingredients. Food protein nanoparticles show promise for oral drug delivery, with improved biosafety and cost-effectiveness compared to polymeric nanoparticles. More importantly, diverse food proteins provide "choice and variety" to meet the challenges faced by different drugs in oral delivery resulting from low solubility, poor permeability, and gastrointestinal stability. The abundance of hydroxyl, amino, and carboxyl groups in food proteins allows easy surface modification of the nanoparticles to impart unique functions. Albeit being in its infancy, food protein nanoparticles exhibit high capability to enhance oral bioavailability of a wide range of drugs from small molecules to biomacromolecules. Considering the rapid growth of the field, the achievements and mechanisms of food protein nanoparticles in enhancing oral bioavailability are reviewed. Factors affecting the performance of food protein nanoparticles are discussed with the purpose to inspire the development of food protein nanoparticle-based oral drug delivery systems.

Response Surface Methodology (RSM) Powered Formulation Development, Optimization and Evaluation of Thiolated Based Mucoadhesive Nanocrystals for Local Delivery of Simvastatin

In oral administration systems, mucoadhesive polymers are crucial for drug localization and target-specific activities. The current work focuses on the application of thiolated xanthan gum (TXG) to develop and characterize a novel mucoadhesive nanocrystal (NC) system of simvastatin (SIM). Preparation of SIM-NC was optimized using response surface methodology (RSM) coupled with statistical applications. The concentration of Pluronic F-127 and vacuum pressure were optimized by central composite design. Based on this desirable approach, the prerequisites of the optimum formulation can be achieved by a formulation having 92.568 mg of F-127 and 77.85 mbar vacuum pressure to result in EE of 88.8747% and PS of 0.137.835 nm. An optimized formulation was prepared with the above conditions along with xanthan gum (XG) and TXG and various parameters were evaluated. A formulation containing TXG showed 98.25% of SIM at the end of 96 h. Regarding the mucoadhesion potential evaluated by measuring zeta potential, TXG-SIM-NC shoed the maximum zeta potential of 16,455.8 ± 869 mV at the end of 6 h. The cell viability percentage of TXG-SIM-NC (52.54 ± 3.4% with concentration of 50 µg/mL) was less than the plain SIM, with XG-SIM-NC showing the highest cytotoxicity on HSC-3 cells. In vivo pharmacokinetic studies confirm the enhanced bioavailability of formulated mucoadhesive systems of SIM-NC, with TXG-SIM-NC exhibiting the maximum.

Microcrystals of Ketal-Linked Paliperidone Prodrugs for Long-Acting Antipsychotics

Intramuscularly injectable long-acting prodrug-based microcrystals (MCs) are of particular interest for chronic disease management. Nevertheless, current prevalently used linkers degraded by enzymes have the potential drawback of substantial differences in enzyme levels between individuals. Here, we reported the synthesis of a stearyl-modified paliperidone prodrug (SKP) with an acid-sensitive ketal linker for developing long-acting MC antipsychotics. SKP-MCs of three different sizes were prepared and systematically examined. We found that paliperidone exposure in SKP-MC-treated rats was prolonged compared with that in rats treated with the commercial antipsychotic Invega Sustenna and that the drug release rate decreased with increasing MC size. In inflammation-inhibition-model rats, paliperidone release from the SKP-MCs was considerably decreased, indicating that the immune-mediated foreign-body response after intramuscular administration boosted paliperidone release. Our findings will provide valuable insights into in vivo drug release from prodrug-based MC formulations. The ketal-linked prodrug strategy might be a new solution for developing long-acting prodrug formulations of hydroxyl-group-bearing drugs.

Biological and Intracellular Fates of Drug Nanocrystals through Different Delivery Routes: Recent Development Enabled by Bioimaging and PK Modeling

Nanocrystals have contributed to exciting improvements in the delivery of poorly water-soluble drugs. The biological and intracellular fates of nanocrystals are currently under debate. Due to the remarkable commercial success in enhancing oral bioavailability, nanocrystals have originally been regarded as a simple formulation approach to enhance dissolution. However, the latest findings from novel bioimaging tools lead to an expanded view. Intact nanocrystals may offer long-term durability in the body and offer drug delivery capabilities like those of other nano-carriers. This review renews the understanding of the biological fates of nanocrystals administered via oral, intravenous, and parenteral (e.g., dermal, ocular, and pulmonary) routes. The intracellular pathways and dissolution kinetics of nanocrystals are explored. Additionally, the future trends for in vitro and in vivo quantification of nanocrystals, as well as factors impacting the biological and intracellular fates of nanocrystals are discussed. In conclusion, nanocrystals present a promising and underexplored therapeutic opportunity with immense potential.

The antisolvent coprecipitation method for enhanced bioavailability of poorly water-soluble drugs

In recent years, poorly water-soluble drug candidates in the drug development pipeline have been a challenging issue for the pharmaceutical industry. Many delivery systems such as nanocrystals, cocrystals, nanoparticles, and amorphous solid dispersions (ASDs) have been developed to overcome these problems. A large number of methods are utilized to realize the above delivery systems. Among all the preparation methods, the antisolvent coprecipitation method is a relatively simple, cost-effective method, offering many advantages over conventional methods. An overview of recent developments for each solubility enhancement approach using the antisolvent coprecipitation method is presented. This current review details a comprehensive overview of the antisolvent coprecipitation process and its properties, as well as the fundamentals for enhancing the solubility and bioavailability of poorly water-soluble drugs by nanotization, polymorph control with polymers and/or surfactants. Furthermore, this review also presents insights into the factors affecting the antisolvent coprecipitation process.

The long-circulating effect of pegylated nanoparticles revisited via simultaneous monitoring of both the drug payloads and nanocarriers

The long-circulating effect is revisited by simultaneous monitoring of the drug payloads and nanocarriers following intravenous administration of doxorubicin (DOX)-loaded methoxy polyethylene glycol-polycaprolactone (mPEG-PCL) nanoparticles. Comparison of the kinetic profiles of both DOX and nanocarriers verifies the long-circulating effect, though of limited degree, as a result of pegylation. The nanocarrier profiles display fast clearance from the blood despite dense PEG decoration; DOX is cleared faster than the nanocarriers. The nanocarriers circulate longer than DOX in the blood, suggesting possible leakage of DOX from the nanocarriers. Hepatic accumulation is the highest among all organs and tissues investigated, which however is reversely proportionate to blood circulation time. Pegylation and reduction in particle size prove to extend circulation of drug nanocarriers in the blood with simultaneous decrease in uptake by various organs of the mononuclear phagocytic system. It is concluded that the long-circulating effect of mPEG-PCL nanoparticles is reconfirmed by monitoring of either DOX or the nanocarriers, but the faster clearance of DOX suggests possible leakage of a fraction of the payloads. The findings of this study are of potential translational significance in design of nanocarriers towards optimization of both therapeutic and toxic effects.

Drug Nanocrystals for Active Tumor-Targeted Drug Delivery

Drug nanocrystals, which are comprised of active pharmaceutical ingredients and only a small amount of essential stabilizers, have the ability to improve the solubility, dissolution and bioavailability of poorly water-soluble drugs; in turn, drug nanocrystal technology can be utilized to develop novel formulations of chemotherapeutic drugs. Compared with passive targeting strategy, active tumor-targeted drug delivery, typically enabled by specific targeting ligands or molecules modified onto the surface of nanomedicines, circumvents the weak and heterogeneous enhanced permeability and retention (EPR) effect in human tumors and overcomes the disadvantages of nonspecific drug distribution, high administration dosage and undesired side effects, thereby contributing to improving the efficacy and safety of conventional nanomedicines for chemotherapy. Continuous efforts have been made in the development of active tumor-targeted drug nanocrystals delivery systems in recent years, most of which are encouraging and also enlightening for further investigation and clinical translation.

Ionic co-aggregates (ICAs) based oral drug delivery: Solubilization and permeability improvement

Due to the overwhelming percentage of poorly water-soluble drugs, pharmaceutical industry is in urgent need of efficient approaches for solubilization and permeability improvement. Salts consisting of lipophilic fatty acid anions and hydrophilic choline cations are found to be surface active and able to form ionic co-aggregates (ICAs) in water. Choline oleate-based ICAs significantly enhance oral absorption of paclitaxel (PTX) as compared with cremophor EL-based micelles (MCs). Aggregation-caused quenching probes enable tracking of intact ICAs in in vivo transport and cellular interaction. Prolonged intestinal retention of ICAs than MCs implies stronger solubilizing capability in vivo. Ex vivo imaging of major organs and intestinal tracts suggests transepithelial transport of intact ICAs. Cellular studies support the enhanced absorption of PTX and transmembrane transport of intact ICAs. In conclusion, ICAs, consisting of lipophilic ions and hydrophilic counter-ions, are of great potential in delivery of poorly water-soluble drugs by enhancing solubility and permeability.

A Nanocrystal Platform Based on Metal-Phenolic Network Wrapping for Drug Solubilization

The preparation of drugs into nanocrystals represents a practical pharmaceutical technology to solubilize poorly water-soluble drugs and enhance bioavailability. However, commonly used stabilizers in nanocrystals like polymers and surfactants are frequently inefficient and cannot stabilize nanocrystals for an expected time. This study reports an exquisite platform for nanocrystal production based on a metal-phenolic network (MPN). MPN-wrapped nanocrystal particles (MPN-NPs) were fabricated through an anti-solvent precipitation method using tannic acid and Fe^III or Al^III as coupling agents and characterized by dynamic light scattering, transmission electron microscope, ultraviolet and visible spectrophotometry, fourier-transform infrared spectroscopy, and X-ray powder diffraction. In vitro release, cytotoxicity, and stability were mainly studied with MPN-NPs loading paclitaxel. The suitability of MPN as a nanocrystal stabilizer was also investigated for other classical hydrophobic drugs, including simvastatin, andrographolide, atorvastatin calcium, ferulic acid, and famotidine. The results showed that MPN could effectively wrap and stabilize various drug nanocrystals apart from famotidine. The maximum solubilization of MPN towards atorvastatin calcium was up to 1587 folds, and it also exhibited an excellent solubilizing effect on other hydrophobic drugs. We disclosed that the drug was entrapped in MPN in the nanocrystal form, and there were distinct physiochemical interactions between MPN and the payload. Our findings suggested that MPN may be a promising platform for nanocrystal production to address the challenge of low solubility associated with hydrophobic drugs. Graphical abstract.

Nanotechnology-Based Drug Delivery System for Anticancer Active Ingredients from Traditional Chinese Medicines: A Review

The variable dosage forms of most traditional Chinese medicines (TCMs) could be disadvantaged by low selectivity, poor biological distribution, limited bioavailability with low efficacy, and some adverse effects. These issues limit the control of clinical pharmacodynamics of the antitumor active components. With the progress of science and technology, many new polymer materials and new technologies have emerged, such as nanotechnology, cyclodextrin inclusion, solid dispersion, microcapsule and microsphere technologies. These new technologies provide a good basis for exploring novel TCM dosage forms for overcoming the shortcomings. The increased numbers of new technologies have been used to study TCM dosage forms with remarkable achievements. In this review paper, we will provide a systematic overview of the new dosage forms of nano-formulations and co-medications in relation to nano-delivery systems in an attempt to provide useful references for practical application of active antitumor ingredients from the TCMs.

Oral delivery of carrier-free dual-drug nanocrystal self-assembled microspheres improved NAD+ bioavailability and attenuated cardiac ischemia/reperfusion injury in mice

Nicotinamide riboside (NR), as a dietary supplement, can be converted to nicotinamide adenine dinucleotide (NAD+) in cells to support mitochondrial energy metabolism. However, the efficacy of oral administrated NR is limited due to its quick degradation in circulation and low bioavailability in targeted organs. In this study, we fabricated nanocrystal self-assembled microspheres by Nano Spray Dryer for oral delivery of NR. The structure of NR and resveratrol (RES) nanocrystal self-assembled microspheres (NR/RESms) is confirmed by the morphology, chemical structure, and crystallization. The NR/RESms displayed restricted NR release at the gastric acid-mimic condition (<15% in the first 8 hours), while achieved accelerated NR release in an enteric-mimic environment (>46% within 8 hours). Oral administration of NR/RESms for 8 hours significantly elevated NAD+ levels in serum (169.88 nM versus 30.93 nM in the NR group, p < .01; and 66.89 nM in the NR + RES group, p < .05), and enhanced NAD+ abundance in multiple organs in mice, exhibiting an improved oral NAD+ bioavailability. In addition, without any serious adverse effects on major organs, oral delivery of NR/RESms attenuated myocardial infarction (15.82% versus 19.38% in the I/R + NR group and 20.76% in the I/R + NR + RES group) in a cardiac ischemia/reperfusion (I/R) injury mouse model. Therefore, our data supported that the NR/RESms is a promising candidate as NAD+ booster for oral administration.

Rod-shaped nintedanib nanocrystals improved oral bioavailability through multiple intestinal absorption pathways

Nintedanib (BIBF) is a biopharmaceutical classification system II (BCS II) drug that has a good therapeutic effect for the treatment of nonsmall cell lung cancer; however, it shows poor oral bioavailability due to low dissolution and intestinal absorption. This study aims to fabricate rod-shaped nanocrystals to enhance oral bioavailability by improving the dissolution and absorption of BIBF in the intestine. By prescription screening, BIBF nanocrystals (BIBF-NCs) with a particle size of 325.30 ± 1.03 nm and zeta potential of 32.70 ± 1.24 mV were fabricated by an antisolvent precipitation-ultrasound approach with a stabilizer of sodium carboxyl methyl cellulose (CMC-Na). BIBF-NCs exhibited a rod-shaped morphology by transmission electron microscopy (TEM). The results of powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) showed that the crystal form of BIBF in BIBF-NCs was altered. The BIBF-NCs remarkably improved the saturation solubility and dissolution of BIBF compared with BIBF powder. According to the results of in situ single-pass intestinal perfusion (SPIP), BIBF-NCs showed improved absorption and membrane permeability, with K_a and P_app values in the jejunum of 0.21 ± 0.01 min^-1 and (4.34 ± 0.11) × 10^-4 cm/min, respectively. Further, the K_a and P_app values of BIBF-NCs were all reduced significantly after the addition of inhibitors colchicine, chlorpromazine and indomethacin, which demonstrated that BIBF-NCs could be absorbed by endocytosis mediated by caveolae and clathrin and micropinocytosis in the intestine. The cell evaluation results showed that BIBF-NCs could be taken up by macrophages and transported from Caco-2 monolayers. The in vivo pharmacokinetic results showed that the bioavailability of the BIBF-NCs was 2.51-fold higher than that of the BIBF solution (BIBF-Sol) after oral administration with a longer T_max (4.50 ± 1.00 h vs. 2.60 ± 1.92 h). In summary, rod-shaped BIBF-NCs could significantly improve oral bioavailability through multiple intestinal absorption pathways.

Cytosolic delivery of the immunological adjuvant Poly I:C and cytotoxic drug crystals via a carrier-free strategy significantly amplifies immune response

Co-delivery of chemotherapeutics and immunostimulant or chemoimmunotherapy is an emerging strategy in cancer therapy. The precise control of the targeting and release of agents is critical in this methodology. This article proposes the asynchronous release of the chemotherapeutic agents and immunostimulants to realize the synergistic effect between chemotherapy and immunotherapy. To obtain a proof-of-concept, a co-delivery system was prepared via a drug-delivering-drug (DDD) strategy for cytosolic co-delivery of Poly I:C, a synthetic dsRNA analog to activate RIG-I signaling, and PTX, a commonly used chemotherapeutics, in which pure PTX nanorods were sequentially coated with Poly I:C and mannuronic acid via stimulating the RIG-I signaling axis. The co-delivery system with a diameter of 200 nm enables profound immunogenicity of cancer cells, exhibiting increased secretion of cytokines and chemokines, pronounced immune response in vivo, and significant inhibition of tumor growth. Also, we found that intracellularly sustained release of cytotoxic agents could elicit the immunogenicity of cancer cells. Overall, the intracellular asynchronous release of chemotherapeutics and immunomodulators is a promising strategy to promote the immunogenicity of cancer cells and augment the antitumor immune response.