Stealth CD44-targeted hyaluronic acid supramolecular nanoassemblies for doxorubicin delivery: probing the effect of uncovalent pegylation degree on cellular uptake and blood long circulation

A Safe-by-Design Strategy towards Safer Nanomaterials in Nanomedicines

The marriage of nanotechnology and medicine offers new opportunities to fight against human diseases. Benefiting from their unique optical, thermal, magnetic, or redox properties, a wide range of nanomaterials have shown potential in applications such as diagnosis, drug delivery, or tissue repair and regeneration. Despite the considerable success achieved over the past decades, the newly emerging nanomedicines still suffer from an incomplete understanding of their safety risks, and of the relationships between their physicochemical characteristics and safety profiles. Herein, the most important categories of nanomaterials with clinical potential and their toxicological mechanisms are summarized, and then, based on this available information, an overview of the principles in developing safe-by-design nanomaterials for medical applications and of the recent progress in this field is provided. These principles may serve as a starting point to guide the development of more effective safe-by-design strategies and to help identify the major knowledge and skill gaps.

pH and redox dual-responsive nanoparticles based on disulfide-containing poly(β-amino ester) for combining chemotherapy and COX-2 inhibitor to overcome drug resistance in breast cancer

Background

Multidrug resistance (MDR) generally leads to breast cancer treatment failure. The most common mechanism of MDR is the overexpression of ATP-binding cassette (ABC) efflux transporters such as P-glycoprotein (P-gp) that reduce the intracellular accumulation of various chemotherapeutic agents. Celecoxib (CXB), a selective COX-2 inhibitor, can dramatically enhance the cytotoxicity of doxorubicin (DOX) in breast cancer cells overexpressing P-gp. Thus it can be seen that the combination of DOX and CXB maybe obtain synergistic effects against breast cancer by overcoming drug resistance.

Results

In this study, we designed a pH and redox dual-responsive nanocarrier system to combine synergistic effects of DOX and CXB against drug resistant breast cancer. This nanocarrier system denoted as HPPDC nanoparticles showed good in vitro stability and significantly accelerated drug releases under the acidic and redox conditions. In drug-resistant human breast cancer MCF-7/ADR cells, HPPDC nanoparticles significantly enhanced the cellular uptake of DOX through the endocytosis mediated by CD44/HA specific binding and the down-regulated P-gp expression induced by COX-2 inhibition, and thus notably increased the cytotoxicity and apoptosis-inducing activity of DOX. In MCF-7/ADR tumor-bearing nude mice, HPPDC nanoparticles showed excellent tumor-targeting ability, remarkably enhanced tumor chemosensitivity and reduced COX-2 and P-gp expressions in tumor tissues.

Conclusion

All results demonstrated that HPPDC nanoparticles can efficiently overcome drug resistance in breast cancer both in vitro and in vivo by combining chemotherapy and COX-2 inhibitor. In a summary, HPPDC nanoparticles show a great potential for combination treatment of drug resistant breast cancer.

A collagen mimetic peptide-modified hyaluronic acid hydrogel system with enzymatically mediated degradation for mesenchymal stem cell differentiation

We have successfully designed and synthesized a biomimetic hydrogel system with maleimide-modified hyaluronic acid (HA) as the backbone and conjugated it to the collagen mimetic peptide (GPO)₈-CG-RGDS. The matrix metalloproteinase (MMP)-sensitive peptide GCRDGPQGI↓WGQDRCG was the cross-linker. HA has high biocompatibility, low immunogenicity, and the capacity to interact with extracellular molecules. Recent studies have found that matrix metalloproteinases (MMPs) are involved in regulating the differentiation of bone mesenchymal stem cells and play a pivotal role in cartilage formation. (GPO)₈-CG-RGDS has a natural collagen partial structure that follows the (Gly-Xaa-Yaa)n sequence, which is controllable in quality and can mimic the structure and biological activity of natural collagen. We found that combining this CMP with a MMP-sensitive peptide may have the potential to induce the differentiation of BMSCs into cartilage and inhibit the hypertrophic phenotype during differentiation. This design allows HA hydrogels to not only bind RGD sequences but also graft other functional peptide sequences to achieve a highly flexible platform with potential for multiple biomedical applications.

MMP-2-responsive gelatin nanoparticles for synergistic tumor therapy

Purpose: The aim of this study was to develop a new type of nanoparticle that enables concentrated drug release and synergistic therapy. Methods: To this end, we synthesized Ge-DOX-5-ALA/NPs, which can enter tumor tissue by the enhanced permeability and retention (EPR) effect and release drugs by utilizing matrix metalloproteinase-2 (MMP-2). Results: The Ge-DOX-5-ALA/NPs were synthesized by a single-phase coacervation method, and the hydrodynamic diameters of all nanoparticles were under 200 nm. The drug encapsulation and loading efficiency were 92%±1.13% and 6.02% ± 0.48%, respectively. Gelatin zymography was performed to detect the expression of MMP-2 in MCF-7 and Hs578Bst cells. The nanoparticle sensitivity to MMP-2 was examined by comparing the release behavior and cellular uptake in MCF-7 and Hs578Bst cells. In vitro cytotoxicity of the nanoparticles was measured by an MTT assay. An in vivo anticancer efficacy study in S180-bearing mice demonstrated that Ge-DOX-5-ALA/NPs provide a substantial curative effect. A pharmacokinetics experiment demonstrated that the nanoparticles have a sustained release effect. Conclusions: The MMP-2-triggered nanoparticles can transport drugs successfully into the tumor site and enable combined chemotherapy and photodynamic therapy.

Exploring the relationship of hyaluronic acid molecular weight and active targeting efficiency for designing hyaluronic acid-modified nanoparticles

Although it is reported that the targeting ability of hyaluronic acid (HA)-based nanoparticles (NPs) is molecular weight (MW) dependent, the influence of HA MW on targeting efficiency of HA-functionalized NPs and the underlying mechanism remain elusive. In this study, we constituted three HA-functionalized Dox-loaded NPs (Dox/HCVs) different HA MWs (7, 63, and 102 kDa) and attempted to illustrate the effects of HA MW on the targeting efficiency. The three Dox/HCVs had similar physiochemical and pharmaceutical characteristics, but showed different affinity to CD44 receptor. Furthermore, Dox/HCV-63 exerted the best targeting effect and the highest cytotoxicity compared with Dox/HCV-7 and Dox/HCV-102. It was interesting to found that both the HA-CD44 binding affinity and induced CD44 clustering by HA-based NPs were HA MW-dependent, the two of which determine the apparent targeting efficacy of Dox/HCV NPs in the conflicting directions. Those results laid a good foundation for rationally designing HA-based NPs in cancer therapy.

A nanoscale photothermal agent based on a metal-organic coordination polymer as a drug-loading framework for effective combination therapy

Metallic materials are widely emerging as photothermal agents owing to their superior photothermal transduction efficiency and satisfactory photostability. In this study, an iron-based coordination polymer (Fe-CNP) loaded with doxorubicin (DOX) was assessed as a dual-function agent for photothermal therapy (PTT) and tumor-targeted chemotherapy. Fe-CNPs were synthesized by a one-step coordination reaction between Fe³⁺, hydrocaffeic acid, and dopamine-modified hyaluronic acid. A drug-loading method was developed to entrap DOX within Fe-CNPs through the formation of coordination bonds by Fe³⁺ and DOX (Scheme 1). DOX release was rapidly triggered in the cellular acidic environment and further enhanced by hyperpyrexia in the part of tumor, which will kill the remaining tumor cells after PTT. Animal experiments demonstrated complete inhibition of tumor growth without recurrence in 21 days after injection of DOX@Fe-CNPs with NIR laser irradiation. These results confirmed the enhanced anti-tumor efficiency of the chemo-photothermal nanosystem. Our work may reveal a photothermal coordination polymer as a drug-loading framework and highlight the development of metal-organic materials in combined chemo-photothermal therapy. STATEMENT OF SIGNIFICANCE: Photothermal therapy (PTT), which could directly act on tumors, has been considered as a promising treatment method for cancer. The combination of PTT with chemotherapy is attracting tremendous attention because such advanced application can achieve personalized precise medicine. Unfortunately, most PTT materials have photobleaching property, which results in reduced photothermal efficiency. Furthermore, their clinical applications also suffer from low loading capacity of chemotherapeutic drugs or nonbiodegradability in the biological system. In this study, we hypothesized that iron-based coordination polymers (Fe-CNPs) could function dually as agents to deliver both PTT and tumor-targeted chemotherapy by coordination loading of the chemotherapeutic drug doxorubicin (DOX). Our work may open up new avenues to rationally design versatile platforms for photothermal-chemotherapy to obtain synergistically enhanced therapeutic efficacy.

Photoelectrochemical Biosensor for Sensitive Detection of Soluble CD44 Based on the Facile Construction of a Poly(ethylene glycol)/Hyaluronic Acid Hybrid Antifouling Interface

The serum level of soluble CD44 is directly associated with several clinicopathological parameters of malignant diseases. There is a great need for the development of an easy and cost-effective detection method for soluble CD44 for both the diagnosis and the treatment of cancers. In this work, a simple photoelectrochemical (PEC) method for the sensitive detection of serum-soluble CD44 is proposed based on the construction of a hybrid antifouling coating on the TiO₂ substrate. Hyaluronic acid (HA) and poly(ethylene glycol) (PEG) are co-immobilized using a biomimetic one-step surface functionalization approach. The immobilized HA shows strong recognition abilities toward soluble CD44, and the synergistic antifouling effect achieved by the combination of PEG and HA improves the sensing specificity. Based on the inhibitory effect of CD44 recognition on the PEC signal of the TiO₂ substrate, a PEC biosensor is developed with a wide response range and a low detection limit. The development of antibody-free biosensors may promote the application of soluble CD44 as a biomarker for the diagnosis and treatment of malignant diseases.

In situ apolipoprotein E-enriched corona guides dihydroartemisinin-decorating nanoparticles towards LDLr-mediated tumor-homing chemotherapy

The therapeutic efficiency of active targeting nanoparticulate drug delivery systems (nano-DDS) is highly compromised by the plasma proteins adsorption on nanoparticles (NPs) surface, which significantly hinders cell membrane receptors to recognize the designed ligands, and provokes the off-target toxicity and rapid clearance of NPs in vivo. Herein, we report a novel dihydroartemisinin (DHA)-decorating nano-DDS that in situ specifically recruits endogenous apolipoprotein E (apoE) on the NPs surface. The apoE-anchored corona is able to prolong PLGA-PEG2000-DHA (PPD) NPs circulation capability in blood, facilitate NPs accumulating in tumor cells by the passive enhanced permeability and retention (EPR) effect and low-density lipoprotein receptor (LDLr)-mediated target transport, and ultimately improve the in vivo antitumor activity. Our findings demonstrate that the strategy of in situ regulated apoE-enriched corona ensures NPs an efficient LDLr-mediated tumor-homing chemotherapy.

Transformative hyaluronic acid-based active targeting supramolecular nanoplatform improves long circulation and enhances cellular uptake in cancer therapy

Hyaluronic acid (HA) is a natural ligand of tumor-targeted drug delivery systems (DDS) due to the relevant CD44 receptor overexpressed on tumor cell membranes. However, other HA receptors (HARE and LYVE-1) are also overexpressing in the reticuloendothelial system (RES). Therefore, polyethylene glycol (PEG) modification of HA-based DDS is necessary to reduce RES capture. Unfortunately, pegylation remarkably inhibits tumor cellular uptake and endosomal escapement, significantly compromising the in vivo antitumor efficacy. Herein, we developed a Dox-loaded HA-based transformable supramolecular nanoplatform (Dox/HCVBP) to overcome this dilemma. Dox/HCVBP contains a tumor extracellular acidity-sensitive detachable PEG shell achieved by a benzoic imine linkage. The in vitro and in vivo investigations further demonstrated that Dox/HCVBP could be in a "stealth" state at blood stream for a long circulation time due to the buried HA ligands and the minimized nonspecific interaction by PEG shell. However, it could transform into a "recognition" state under the tumor acidic microenvironment for efficient tumor cellular uptake due to the direct exposure of active targeting ligand HA following PEG shell detachment. Such a transformative concept provides a promising strategy to resolve the dilemma of natural ligand-based DDS with conflicting two processes of tumor cellular uptake and in vivo nonspecific biodistribution.

PEGylated hyaluronidase/NIR induced drug controlled release system for synergetic chemo-photothermal therapy of hepatocellular carcinoma

In recent years, cancer treatment has been facing the challenge of increasing antitumor efficiency and avoiding severe adverse effects simultaneously. In this study, we designed a controlled release drug delivery system, doxorubicin (Dox)-loaded and hyaluronic acid (HA)-modified PEGylated gold nanocages (AuNCs), which was designated as PEG-HAn-AuNCs/Dox (n represented 10ⁿ HA repeating units were modified on each AuNC). In this system, AuNCs were applied as the photothermal cores, Dox was employed as the model drug, HA was applied as the tumor-microenvironment responsive switch to achieve controlled release, and poly (ethylene glycol) (PEG) was used as the stealth polymer to prolong systemic circulation time. Firstly, we evaluated the physical and chemical properties of the PEG-HAn-AuNCs/Dox with different ratios of HA to AuNC and found that PEG-HA4-AuNCs/Dox was the optimal. Secondly, PEG-HA4-AuNCs/Dox revealed the feature of controlled release, namely, the drug release was triggered by hyaluronidase (HAase) and accelerated by the acidic pH and near-infrared (NIR) irradiation. And then PEG-HA4-AuNCs/Dox could be effectively delivered to a cultured SMMC-7721 cell line in vitro and the tumor tissues of the subcutaneous mouse models of hepatocellular carcinoma (HCC) in vivo. Finally, the results demonstrated the synergetic therapy, namely the combination of chemotherapy and photothermal therapy (PTT) (defined as chemo-photothermal therapy) mediated by PEG-HA4-AuNCs/Dox, could efficiently inhibit the tumor growth both in vitro and in vivo. Therefore, the advantages of PEG-HA4-AuNCs/Dox endowed it as a great potential candidate for HCC treatment.

Hyaluronic acid-capped compact silica-supported mesoporous titania nanoparticles for ligand-directed delivery of doxorubicin

Mesoporous titania nanoparticles (MTN), owing to their high surface area to volume ratio and tunable pore sizes, appear capable of delivering sizable amounts of drug payloads, and hence, show considerable promise as drug delivery candidates in cancer therapy. We designed silica-supported MTN (MTNst) coated with hyaluronic acid (HA) to effectively deliver doxorubicin (DOX) for breast cancer therapy. The HA coating served a dual purpose of stabilizing the payload in the carriers as well as actively targeting the nanodevices to CD44 receptors. The so-formed HA-coated MTNst carrying DOX (HA/DOX-MTNst) had spheroid particles with a considerable drug-loading capacity and showed significantly superior in vitro cytotoxicity against MDA-MB-231 cells as compared to free DOX. HA/DOX-MTNst markedly improved the cellular uptake of DOX in an apparently CD44 receptor-dependent manner, and increased the number of apoptotic cells as compared to free DOX. These nanoplatforms accumulated in large quantities in the tumors of MDA-MB-231 xenograft tumor-bearing mice, where they significantly enhanced the inhibition of tumor growth compared to that observed with free DOX with no signs of acute toxicity. Based on these excellent results, we deduced that HA/DOX-MTNst could be successfully used for targeted breast cancer therapy. STATEMENT OF SIGNIFICANCE: This is the first study to use silica-supported mesoporous titania nanoparticles (MTNst) for doxorubicin (DOX) delivery to treat breast cancer, which exhibited effective and enhanced in vitro and in vivo apoptosis and tumor growth inhibition. Solid silica was used to support the mesoporous TiO₂ resulting in MTNst, which efficiently incorporated a high DOX payload. The hyaluronic acid (HA) coating over the MTNst surface served a dual purpose of first, stabilizing DOX inside the MTNst (capping agent), and second, directing the nanoplatform device to CD44 receptors that are highly expressed in MDA-MB-231 cells (targeting ligand). The NPs exhibited highly efficacious in vitro tumor-cell killing and excellent in vivo tumor regression, highlighting the enormous promise of this system for breast cancer therapy.

Nanoengineering of Poly(ethylene glycol) Particles for Stealth and Targeting

The assembly of particles composed solely or mainly of poly(ethylene glycol) (PEG) is an emerging area that is gaining increasing interest within bio-nano science. PEG, widely considered to be the "gold standard" among polymers for drug delivery, is providing a platform for exploring fundamental questions and phenomena at the interface between particle engineering and biomedicine. These include the targeting and stealth behaviors of synthetic nanomaterials in biological environments. In this feature article, we discuss recent work in the nanoengineering of PEG particles and explore how they are enabling improved targeting and stealth performance. Specific examples include PEG particles prepared through surface-initiated polymerization, mesoporous silica replication via postinfiltration, and particle assembly through metal-phenolic coordination. This particle class exhibits unique in vivo behavior (e.g., biodistribution and immune cell interactions) and has recently been explored for drug delivery applications.

Precisely albumin-hitchhiking tumor cell-activated reduction/oxidation-responsive docetaxel prodrugs for the hyperselective treatment of breast cancer

The anticancer efficacy of chemotherapy is greatly limited by short blood circulation and poor tumor selectivity. Thus, anticancer prodrugs with prolonged systemic circulation, tumor-specific distribution and bioactivation, could significantly strengthen the chemotherapy efficacy. Herein, we design two novel tumor cell reduction/oxidation-responsive docetaxel (DTX) prodrugs, DTX-maleimide conjugates with disulfide bond (DSSM) or thioether bond (DSM) linkages, to evaluate the roles of different sensitive linkages in drug release, pharmacokinetics and therapeutic efficacy. An ester bond-linkage prodrug (DM) is utilized as a non-sensitive control. DSSM and DSM show reduction- or oxidation-sensitive release behavior, respectively, and exhibit hyperselective bioactivation and cytotoxicities between cancerous and normal cells. They could instantly hitchhike blood circulating albumin after i.v. administration with albumin-binding half-lives as short as 1 min, resulting in prolonged systemic circulation, increased tumor accumulation. In response to the upregulated reduction/oxidation environment within tumor cells, DSSM and DSM exhibit selectively release capacity in tumor tissues, their TAITumor/Liver values are over 30-fold greater than DM. Combining the above delivery advantages into one, DSSM and DSM achieve enhanced antitumor efficacy of DTX. Such a uniquely developed strategy, integrating high albumin-binding capability and reduction/oxidation-sensitive drug superselective release in tumors, has great potential to be applied in clinical cancer therapy.

Comparison of hyaluronic acid-based micelles and polyethylene glycol-based micelles on reversal of multidrug resistance and enhanced anticancer efficacy in vitro and in vivo

Polyethylene glycol (PEG)-based block copolymer micelles and hyaluronic acid (HA)-based grafted copolymer micelles have been widely investigated in chemotherapy. In this study, to evaluate the differences among HA-based grafted polymer micelles, PEG-based block polymer micelles and the mixed of these two micelles in enhancing antitumor effects and overcoming MDR, two amphiphilic vitamin E succinate (VES) derivatives, HA VES (HA-g-VES) and PEG 2000 VES (TPGS2k), were applied as nanocarriers to prepare HA-VES micelles (HA-PMs), TPGS2k micelles (TPGS2k-PMs) and the mixed micelles (HA/TPGS2k-PMs) for the co-delivery of doxorubicin (DOX) and curcumin (Cur). With the addition of TPGS2k, the particle size of HA/TPGS2k-PMs (153.37 ± 1.00 nm) was smaller than that of HA-PMs (223.83 ± 1.84) but significantly larger than that of TPGS2k-PMs (about 20 nm). The loading efficiency of HA/TPGS2k-PMs was 7.10%, which was lower than HA-PMs (8.31 ± 0.15%) but higher than TPGS2k-PMs (4.38 ± 0.24%). In vitro, HA/TPGS2k-PMs and TPGS2k-PMs exhibited higher cytotoxicity and reversal MDR effects than HA-PMs in MCF-7/Adr cells. However, HA/TPGS2k-PMs, HA-PMs and TPGS2k-PMs all significantly improved the tumor biodistribution, the antitumor effects and reduced the side effects of DOX in 4T1-tumor-bearing mice, but these three micelles displayed no differences in vivo. Therefore, EPR passive targeting effects caused by PEGylated micelles and CD44 active targeting effects caused by HA-based micelles have no significant variance in the delivery of antitumor drugs by i.v.

Synergized Multimodal Therapy for Safe and Effective Reversal of Cancer Multidrug Resistance Based on Low-Level Photothermal and Photodynamic Effects

Despite the therapeutic usefulness of near-infrared irradiation (NIR)-induced potent photothermal effects (PTE) and photodynamic effects (PDE), they inevitably damage normal tissues, often posing threat to life when treating tumors adjacent to key organs or major blood vessels. In this study, the frequently overlooked, "weak" PTE and PDE (no killing capability) are employed to synergize chemotherapy against multidrug resistance (MDR) without impairing normal tissues. An NIR-responsive nanosystem, gold (Au)-nanodot-decorated hollow carbon nanospheres coated with hyaluronic acid, is synthesized as a doxorubicin (DOX) carrier with excellent photothermal and photodynamic properties. Upon low-level infrared irradiation, the mild heat of weak PTE moderately boosts DOX unloading, meanwhile the weak PDE moderately disturbs the P-glycoprotein function for retaining intracellular DOX by impairing mitochondrial ATP production. These two "moderate" alterations are quantitatively and functionally sufficient to augment the efficacy of chemotherapy in reversing MDR without damaging neighboring tissue. Thus, this work creates a gold-dot-decorated nanocarbon spheres based nanosystem for trimodal therapy, reveals the therapeutic value of the frequently ignored weak PTE/PDE, and demonstrates that synergizing with chemotherapy to overcome drug resistance does not necessarily require potent PTE/PDE.

Indocyanine green loaded hyaluronan-derived nanoparticles for fluorescence-enhanced surgical imaging of pancreatic cancer

Pancreatic ductal adenocarcinoma is highly lethal and surgical resection is the only potential curative treatment for the disease. In this study, hyaluronic acid derived nanoparticles with physico-chemically entrapped indocyanine green, termed NanoICG, were utilized for intraoperative near infrared fluorescence detection of pancreatic cancer. NanoICG was not cytotoxic to healthy pancreatic epithelial cells and did not induce chemotaxis or phagocytosis, it accumulated significantly within the pancreas in an orthotopic pancreatic ductal adenocarcinoma model, and demonstrated contrast-enhancement for pancreatic lesions relative to non-diseased portions of the pancreas. Fluorescence microscopy showed higher fluorescence intensity in pancreatic lesions and splenic metastases due to NanoICG compared to ICG alone. The in vivo safety profile of NanoICG, including, biochemical, hematological, and pathological analysis of NanoICG-treated healthy mice, indicates negligible toxicity. These results suggest that NanoICG is a promising contrast agent for intraoperative detection of pancreatic tumors.

CD44-Targeted Facile Enzymatic Activatable Chitosan Nanoparticles for Efficient Antitumor Therapy and Reversal of Multidrug Resistance

Nanoparticles are attractive platforms for the delivery of various anticancer therapeutics. Nevertheless, their applications are still limited by the relatively low drug loading capacity and the occurrence of multidrug resistance (MDR) against chemotherapeutics. In this study, we report that the integration of d-α-tocopherol succinate (VES) residue with both chitosan and paclitaxel (PTX) led to significant improvement of drug loading capacity and drug loading efficiency through the enhancement of drug/carrier interaction. After the incorporation of hyaluronic acid containing PEG side chains (HA-PEG), higher serum stability and more efficient cellular uptake were obtained. Due to HA coating, VES residues and the enzymatic responsive drug release property, such facile nanoparticles actively targeted cancer cells that overexpress CD44 receptor and efficiently reversed the MDR of treated cells, but caused no significant toxicity to mouse fibroblast (NIH-3T3). More importantly, with HA-PEG coating, longer blood circulation and more effective tumor accumulation were achieved for prodrug nanoparticles. Finally, superior anticancer activity and excellent safety profile was demonstrated by HA-PEG coated enzymatically activatable prodrug nanoparticles compared to commercially available Taxol formulation.

Suppress orthotopic colon cancer and its metastasis through exact targeting and highly selective drug release by a smart nanomicelle

The treatment of metastatic cancer is a huge challenge at the moment. Highly precise targeting delivery and drug release in tumor have always been our pursuit in cancer therapy, especially to advance cancer with metastasis, for increasing the efficacy and biosafety. We established a smart nanosized micelle, formed by tocopherol succinate (TOS) conjugated hyaluronic acid (HA) using a disulfide bond linker. The micelle (HA-SS-TOS, HSST) can highly specifically bind with CD44 receptor over-expressed tumor, and response selectively to high GSH level in the cells, inducing disulfide bond breakage and the release of the payload (paclitaxel, PTX). To predict the antitumor efficacy of the micelles more clinically, we established an orthotopic colon cancer model with high metastasis rate, which could be visualized by the luciferase bioluminescence. Our data confirmed CD44 high expression in the colon cancer cells. Highly matching between the micellar fluorescence and bioluminescence of cancer cells in intestines demonstrated an exact recognition of our micelles to orthotopic colon tumor and its metastatic cells, attributing to the mediation of CD44 receptors. Furthermore, the fluorescence of the released Nile Red from the micelles was found only in the tumor and its metastatic cells, and almost completely overlapped with the bioluminescence of the cancer cells, indicating a highly selective drug release. Our micelles presented an excellent therapeutic effect against metastatic colon cancer, and induced significantly prolonged survival time for the mice, which might become a promising nanomedicine platform for the future clinical application against advanced cancers with high CD44 receptor expression.

In situlow-immunogenic albumin-conjugating-corona guiding nanoparticles for tumor-targeting chemotherapy

Thein siturecruited albumin corona enables NPs' tumor-targeting and enhanced antitumor activityin vivo.

Reduction-responsive core-crosslinked hyaluronic acid-b-poly(trimethylene carbonate-co-dithiolane trimethylene carbonate) micelles: synthesis and CD44-mediated potent delivery of docetaxel to triple negative breast tumor in vivo

Docetaxel-loaded core crosslinked HA-P(TMC-DTC) micelles show high targetability to CD44-overexpressing MDA-MB-231 breast tumor and effectively inhibit tumor growth.

Co-administration of biocompatible self-assembled polylactic acid–hyaluronic acid block copolymer nanoparticles with tumor-penetrating peptide-iRGD for metastatic breast cancer therapy

The safe and efficient targeted delivery of chemotherapeutic drugs has remained a challenge in metastatic breast cancer therapy.

Nanocarriers for spleen targeting: anatomo-physiological considerations, formulation strategies and therapeutic potential

There are several clinical advantages of spleen targeting of nanocarriers. For example, enhanced splenic concentration of active agents could provide therapeutic benefits in spleen resident infections and hematological disorders including malaria, hairy cell leukemia, idiopathic thrombocytopenic purpura, and autoimmune hemolytic anemia. Furthermore, spleen delivery of immunosuppressant agents using splenotropic carriers may reduce the chances of allograft rejection in organ transplantation. Enhanced concentration of radiopharmaceuticals in the spleen may improve visualization of the organ, which could provide benefit in the diagnosis of splenic disorders. Unique anatomical features of the spleen including specialized microvasculature environment and slow blood circulation rate enable it an ideal drug delivery site. Because there is a difference in blood flow between spleen and liver, splenic delivery is inversely proportional to the hepatic uptake. It is therefore desirable engineering of nanocarriers, which, upon intravenous administration, can avoid uptake by hepatic Kupffer cells to enhance splenic localization. Stealth and non-spherical nanocarriers have shown enhanced splenic delivery of active agents by avoiding hepatic uptake. The present review details the research in the field of splenotropy. Formulation strategies to design splenotropic drug delivery systems are discussed. The review also highlights the clinical relevance of spleen targeting of nanocarriers and application in diagnostics.

Multifunctionalized polyethyleneimine-based nanocarriers for gene and chemotherapeutic drug combination therapy through one-step assembly strategy

Gene therapy combined with chemotherapy to achieve synergistic therapeutic effects has been a hot topic in recent years. In this project, the human tumor necrosis factor-related apoptosis-inducing ligand-encoding plasmid gene (TRAIL) and doxorubicin (Dox)-coloaded multi-functional nanocarrier was constructed based on the theory of circulation, accumulation, internalization, and release. Briefly, polyethyleneimine (PEI) was selected as skeleton material to synthesize PEI–polyethylene glycol (PEG)–TAT (PPT). Dox was conjugated to PEI using C6-succinimidyl 6-hydrazinonicotinate acetone hydrazone (C6-SANH), and a pH-sensitive Dox-PEI (DP) conjugate was obtained. Then, intracellular cationic pH-sensitive cellular assistant PPT and DP were mixed to condense TRAIL, and TRAIL–Dox coloaded PPT/DP/TRAIL (PDT) nanocarriers were obtained by one-step assembly. TRAIL was completely condensed by DP or PPT when mass ratios (DP/PPT to TRAIL) were up to 100:64, which indicated that DP and PPT could be mixed at any ratio for TRAIL condensation. The intracellular uptake rate of PDT was enhanced (P<0.05) when the contents of PPT in PPT+DP increased from 0 to 30%. Free Dox and TRAIL-loaded nanocarriers (PPT/C6-SANH-PEI/TRAIL [PCT]) were selected as controls to verify the synergistic antitumor effects of PDT. Compared with free TRAIL, TRAIL-protein expression was upregulated by PDT and PCT on Western blotting assays. The in vitro cytotoxicity of PDT was significantly enhanced compared to free Dox and PCT (P<0.01). Furthermore, murine PDT nanocarriers showed higher in vivo antitumor ability than both the Dox group (P<0.05) and the murine PCT group (P<0.05). These results indicated that the TRAIL + Dox synergistic antitumor effect could be achieved by PDT, which paves the way to gene–drug combination therapy for cancer.

The effect of particle shape on cellular interaction and drug delivery applications of micro- and nanoparticles

Encapsulation of therapeutic agents in nanoparticles offers several benefits including improved bioavailability, site specific delivery, reduced toxicity and in vivo stability of proteins and nucleotides over conventional delivery options. These benefits are consequence of distinct in vivo pharmacokinetic and biodistribution profile of nanoparticles, which is dictated by the complex interplay of size, surface charge and surface hydrophobicity. Recently, particle shape has been identified as a new physical parameter which has exerted tremendous impact on cellular uptake and biodistribution, thereby in vivo performance of nanoparticles. Improved therapeutic efficacy of anticancer agents using non-spherical particles is the recent development in the field. Additionally, immunological response of nanoparticles was also altered when antigens were loaded in non-spherical nanovehicles. The apparent impact of particle shape inspired the new research in the field of drug delivery. The present review therefore details the research in this field. The review focuses on methods of fabrication of particles of non-spherical geometries and impact of particle shape on cellular uptake, biodistribution, tumor targeting and production of immunological responses.

Recent advances in TPGS-based nanoparticles of docetaxel for improved chemotherapy

Docetaxel (DTX) is one of the important antitumor drugs, being used in several common chemotherapies to control leading cancer types. Severe toxicities of the DTX are prominent due to sudden parenteral exposure of desired loading dose to maintain the therapeutic concentration. Field of nanotechnology is leading to resist sudden systemic exposure of DTX with more specific delivery to the site of cancer. Further nanometric size range of the formulation aid for prolonged circulation, thereby extensive exposure results better efficacy. In this article, we extensively reviewed the therapeutic benefit of incorporating d-α-tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS, or simply TPGS) in the nanoparticle (NP) formulation of DTX for improved delivery, tumor control and tolerability. TPGS is well accepted nonionic-ampiphilic polymer which has been identified in the role of emulsifier, stabilizer, penetration enhancer, solubilizer and in protection in micelle. Simultaneously, P-glycoprotein inhibitory activity of TPGS in the multidrug resistant (MDR) cancer cells along with its apoptotic potential are the added advantage of TPGS to be incorporated in nano-chemotherapeutics. Thus, it could be concluded that TPGS based nanoparticulate application is an advanced approach to improve therapeutic efficacy of chemotherapeutic agents by better internalization and sustained retention of the NPs.

pH-Responsive de-PEGylated nanoparticles based on triphenylphosphine-quercetin self-assemblies for mitochondria-targeted cancer therapy

We have developed mitochondria-targeted self-assembled nanoparticles (NPs) based on amphiphilic triphenylphosphine-quercetin (TPP-Que) conjugates, which were further modified by poly(ethylene glycol) via a pH-responsive coordination bond to form TQ-PEG NPs. And it is revealed that the TQ-PEG NPs were more effective therapeutic agents compared with Que in vitro and in vivo.

Stepwise pH-responsive nanoparticles for enhanced cellular uptake and on-demand intracellular release of doxorubicin

Physicochemical properties, including particle size, zeta potential, and drug release behavior, affect targeting efficiency, cellular uptake, and antitumor effect of nanocarriers in a formulated drug-delivery system. In this study, a novel stepwise pH-responsive nanodrug delivery system was developed to efficiently deliver and significantly promote the therapeutic effect of doxorubicin (DOX). The system comprised dimethylmaleic acid-chitosan-urocanic acid and elicited stepwise responses to extracellular and intracellular pH. The nanoparticles (NPs), which possessed negative surface charge under physiological conditions and an appropriate nanosize, exhibited advantageous stability during blood circulation and enhanced accumulation in tumor sites via enhanced permeability and retention effect. The tumor cellular uptake of DOX-loaded NPs was significantly promoted by the first-step pH response, wherein surface charge reversion of NPs from negative to positive was triggered by the slightly acidic tumor extracellular environment. After internalization into tumor cells, the second-step pH response in endo/lysosome acidic environment elicited the on-demand intracellular release of DOX from NPs, thereby increasing cytotoxicity against tumor cells. Furthermore, stepwise pH-responsive NPs showed enhanced antiproliferation effect and reduced systemic side effect in vivo. Hence, the stepwise pH-responsive NPs provide a promising strategy for efficient delivery of antitumor agents.

Preparation of intravenous injection nanoformulation via co-assemble between cholesterylated gemcitabine and cholesterylated mPEG: enhanced cellular uptake and intracellular drug controlled release

The objective of this study was to prepare the CHS-mPEG/CHS-dFdC nanoformulation could be administrated through intravenous injection in nude mice. Particularly, CHS-mPEG was selected to co-assemble with CHS-dFdC to improve the prodrug concentration and enhance the stability of nanoformulation. The nanoformulation could be prepared by codissolution-coprecipitation. All of the nanoformulations kept stable in PBS at 4 °C or simulative human plasma at 37 °C. As molar ratios of CHS-mPEG₁₉₀₀/CHS-dFdC increased from 0.1/1 to 2/1, the weight concentration of CHS-dFdC increased from 2.5 to 15 mg/mL. It was found the optimal CHS-mPEG₁₉₀₀/CHS-dFdC nanoformulation displayed controlled drug release in simulative lysosome condition. The amount of released dFdC reached up to 90% within 10 h. It also exhibited enhanced cellular uptake ability, 7-folds higher than that of dFdC during 2.5 h incubation. And it showed superior cytotoxicity resulted from the enhanced cellular uptake ability on BxPC-3 cells.

pH-triggered degradable polymeric micelles for targeted anti-tumor drug delivery

2-(Octadecyloxy)-1,3-dioxan-5-amine (OD) with an acid degradable ortho ester group was synthesized, and conjugated to hyaluronic acid (HA) backbone to prepare pH-responsive and tumor-targeted hyaluronic acid-2-(octadecyloxy)-1,3-dioxan-5-amine (HOD) conjugates. ¹H NMR was used to confirm the structures of the OD and HOD. The studies of pH-responsive behavior showed that HOD micelles were stable under physiological conditions while they were degraded in the tumor acidic microenvironment. Doxorubicin (DOX)-loaded HOD micelles (DOX/HOD) with a narrow size distribution were prepared and characterized. The increased release of DOX from DOX/HOD micelles was presented at low pH condition. From in vitro cytotoxicity assays against MCF-7 cells, the blank micelles exhibited low cytotoxicity, but DOX/HOD micelles had the higher cytotoxicity than pH insensitive control and free DOX. Cellular uptake experiments and confocal images demonstrated that pH-sensitive DOX/HOD micelles could be internalized efficiently by CD44 receptor mediated endocytosis, and then DOX was rapidly released due to pH-induced degradable of OD to cell nucleus compared to the non-sensitive micelles. Furthermore, endocytosis inhibition studies presented that DOX/HOD micelles were internalized into cells mainly via caveolae-mediated routes. In vivo study of micelles in tumor-bearing mice indicates that HOD micelles were more effectively accumulated into the tumor tissue than HOA micelles. These results verify that the pH-sensitive HOD micellar system is a promising nanocarrier for enhanced internalization of antitumor drugs to cancer cells.

Biomacromolecule/lipid hybrid nanoparticles for controlled delivery of sorafenib in targeting hepatocellular carcinoma therapy

Aim: Hybrids composed of various materials are highly versatile for drug delivery in tumor therapy including hepatocellular carcinoma. Herein, a sorafenib (SF)-loaded biomacromolecule hyaluronic acid (HA)/lipid hybrid nanoparticles (HA/SF-cLNS) were developed for targeting drug delivery. Materials & methods: In vitro assays determined HA/SF-cLNS release behavior, enzymatic degradation, uptake and cytotoxicity. H22-bearing liver cancer xenograft murine models were used to evaluate the biodistribution and therapeutic efficacy in vivo. Results: HA/SF-cLNS could be disassembled and drug was released in response to hyaluronidase. In vivo imaging results demonstrated HA/cLNS could enhance drug accumulation at tumor site. Meanwhile, HA/SF-cLNS exhibited improved antitumor efficacy in vitro and in vivo. Conclusion: HA/SF-cLNS demonstrated the potential to enhance antitumor efficacy of SF.

Phosphorylcholine micelles decorated by hyaluronic acid for enhancing antitumor efficiency

DOX-loaded PCL-PDEAMPC micelles coated with HA by electrostatic attraction for enhancing antitumor efficiency and prolonging blood circulation time.

Co-delivery of hydrophilic gemcitabine and hydrophobic paclitaxel into novel polymeric micelles for cancer treatment

Schematic illustration of the preparation and intracellular performance of GEM–VE and PTX–VE loaded FA–PEG–VE micelle.

The effect of dual-functional hyaluronic acid-vitamin E succinate micelles on targeting delivery of doxorubicin

Tumor-targeted delivery system has been developed as an attractive strategy for effective tumor therapy. In this study, in order to enhance the antitumor effects of doxorubicin (DOX), amphiphilic hyaluronic acid (HA)-conjugated vitamin E succinate (VES) copolymers (HA-VES) with different degrees of substitution (DS) were prepared with synergistic antitumor effects and active targeting activities, and utilized as nanocarriers for the efficient delivery of DOX. DOX-loaded HA-VES polymeric micelles (HA-VES/DOX) self-assembled from dual-functional HA-VES copolymer and exhibited excellent loading efficiency and superior colloidal stability. In vitro, HA-VES/DOX displayed enhanced cytotoxicity with synergistic anticancer effects of HA-VES copolymer, high apoptosis-inducing activities of tumor cells, and reversal effects of DOX on multidrug resistance, in comparison with DOX. Also, in vitro cellular uptake and subcellular localization studies revealed that HA-VES/DOX could more efficiently internalize into cancer cells and selectively release DOX within lysosomes, thereby enhancing the distribution of DOX in nuclei and facilitating its interactions with DNA. Specifically, HA-VES/DOX decreased the activity of CD44 mRNA and improved the targeting efficiency on MCF-7 cells, based on the active recognition between HA and CD44 receptor. More importantly, HA-VES/DOX displayed better tumor accumulation and targeting, and enhanced antitumor efficacy with reduced systemic toxicity in 4T1 tumor-bearing mice. In summary, the developed HA-VES-based drug delivery system, which increased drug targeting on the tumor site and exhibited preferable anticancer activity, could hold great potential as an effective and promising strategy for efficient tumor therapy.

Targeted delivery of doxorubicin to tumour tissues by a novel legumain sensitive polygonal nanogel

Targeted delivery of cytotoxic drugs to tumour tissue has great importance for successful chemotherapy. Legumain is an asparaginyl endopeptidase that is highly up-regulated in a number of solid tumours. The aim of this work was to prepare a novel hyaluronic acid (HA) based legumain sensitive nanogel for the delivery of doxorubicin with a high targeting efficiency both in vitro and in vivo. The legumain sensitive property is achieved by the conjugation of doxorubicin with HA via a legumain substrate peptide bridge. This HA derivative is further crosslinked in a water/oil solvent system to form a polygonal nanogel. Doxorubicin released in the tumour tissue is sustained thanks to the combined action of legumain and hyaluronidase, which are both overexpressed in tumour tissues. Hyaluronic acid could act as a targeting agent to CD44 (HA receptor), which further improved the in vivo target effect and enhanced in vitro cellular uptake. The developed nanogel exhibited a high therapeutic index that improved tumour inhibition effects and reduced system toxicity in a lung cancer mice model. These results highlighted the advantages of using this multi-functional material for a successful delivery of doxorubicin against cancer.