Dextran-based fluorescent nanoprobes for sentinel lymph node mapping

Spatiotemporal Mapping of Lymphatic Metastases in Gastric Cancer Using Tumor-Trackable and Enzyme-Activatable Near-Infrared Fluorescent Nanoprobes

Sentinel lymph node biopsy holds significant importance in cancer management, yet the challenge persists in early detection and precise resection of metastasis lymph nodes (LNs) due to the absence of specific and sensitive optical probes. This study reports metastatic LN reporters (MLRs) with an activatable optical output for accurate spatiotemporal mapping of lymphatic metastases in gastric cancer. MLRs are self-assembled entities incorporating mixed amphiphiles with a lipophilic tail and a tumor-targeting ligand or a fluorescent moiety that is caged with a switch cleavable by tumor-specific β-galactosidase (β-Gal). After draining into LNs, MLRs selectively activate their near-infrared fluorescence in the presence of spreading tumor cells. In orthotopic gastric cancer mouse models, the representative reporter MLR1 distinguishes macro/micrometastatic LNs from benign LNs and enables early detection of skip LNs metastasis patterns in a spatial-dependent manner. Such an active sensing mechanism provides a high level of sensitivity and specificity comparable to those of flow cytometry analysis. In surgically resected patient specimens, MLR1 differentiates cancerous tissues and metastatic LNs from normal tissues and benign LNs within 1 h. This study thus presents NIRF nanoprobes that permit facile detection of LN metastases in GC patient samples and highlights a generic translatable nanoprobe design for understanding metastatic progression.

Advances in molecular imaging and targeted therapeutics for lymph node metastasis in cancer: a comprehensive review

Lymph node metastasis is a critical indicator of cancer progression, profoundly affecting diagnosis, staging, and treatment decisions. This review article delves into the recent advancements in molecular imaging techniques for lymph nodes, which are pivotal for the early detection and staging of cancer. It provides detailed insights into how these techniques are used to visualize and quantify metastatic cancer cells, resident immune cells, and other molecular markers within lymph nodes. Furthermore, the review highlights the development of innovative, lymph node-targeted therapeutic strategies, which represent a significant shift towards more precise and effective cancer treatments. By examining cutting-edge research and emerging technologies, this review offers a comprehensive overview of the current and potential impact of lymph node-centric approaches on cancer diagnosis, staging, and therapy. Through its exploration of these topics, the review aims to illuminate the increasingly sophisticated landscape of cancer management strategies focused on lymph node assessment and intervention.

Regulating Electron Acceptor Unit to Construct Conjugated Polymer Probe for Raman Imaging of Tumor and Sentinel Lymph Nodes

Donor-acceptor (D-A) conjugated polymers have large Stokes shifts, high photostability, and good biocompatibility and thus are ideal for use as Raman probes in vivo. However, few D-A conjugated polymers are used as Raman probes for Raman imaging due to their weak Raman signal intensity and intrinsic fluorescence interference. Here, we developed a D-A conjugated polymer probe (CDT-TT) containing alternating cyclopentadithiophene-thienothiophene units for Raman imaging of tumor and sentinel lymph nodes (SLNs). The CDT-TT shows a strong Raman signal at 1389 cm-1 without fluorescence and lipid background signal interference under 785 nm near-infrared light. Moreover, the CDT-TT loaded nanoparticles realized the accurate imaging of tumor cells and tumor tissues. In addition, a high-resolution margin imaging of in situ SLNs was acquired. Taken together, the established method is effective for accurate Raman detection of tumors and SLNs, which may shed new light on the development of D-A polymer Raman probes for clinical imaging.

Advances in nanomedicines for lymphatic imaging and therapy

Lymph nodes play a pivotal role in tumor progression as key components of the lymphatic system. However, the unique physiological structure of lymph nodes has traditionally constrained the drug delivery efficiency. Excitingly, nanomedicines have shown tremendous advantages in lymph node-specific delivery, enabling distinct recognition and diagnosis of lymph nodes, and hence laying the foundation for efficient tumor therapies. In this review, we comprehensively discuss the key factors affecting the specific enrichment of nanomedicines in lymph nodes, and systematically summarize nanomedicines for precise lymph node drug delivery and therapeutic application, including the lymphatic diagnosis and treatment nanodrugs and lymph node specific imaging and identification system. Notably, we delve into the critical challenges and considerations currently facing lymphatic nanomedicines, and futher propose effective strategies to address these issues. This review encapsulates recent findings, clinical applications, and future prospects for designing effective nanocarriers for lymphatic system targeting, with potential implications for improving cancer treatment strategies.

Bioengineered nanogels for cancer immunotherapy

Recent years have witnessed increasingly rapid advances in nanocarrier-based biomedicine aimed at improving treatment paradigms for cancer. Nanogels serve as multipurpose and constructed vectors formed via intramolecular cross-linking to generate drug delivery systems, which is attributed predominantly to their satisfactory biocompatibility, bio-responsiveness, high stability, and low toxicity. Recently, immunotherapy has experienced unprecedented growth and has become the preferred strategy for cancer treatment, and mainly involves the mobilisation of the immune system and an enhanced anti-tumour immunity of the tumour microenvironment. Despite the inspiring success, immunotherapeutic strategies are limited due to the low response rates and immune-related adverse events. Like other nanomedicines, nanogels are comparably limited by lower focal enrichment rates upon introduction into the organism via injection. Because nanogels are three-dimensional cross-linked aqueous materials that exhibit similar properties to natural tissues and are structurally stable, they can comfortably cope with shear forces and serum proteins in the bloodstream, and the longer circulation life increases the chance of nanogel accumulation in the tumour, conferring deep tumour penetration. The large specific surface area can reduce or eliminate off-target effects by introducing stimuli-responsive functional groups, allowing multiple physical and chemical modifications for specific purposes to improve targeting to specific immune cell subpopulations or immune organs, increasing the bioavailability of the drug, and conferring a low immune-related adverse events on nanogel therapies. The slow release upon reaching the tumour site facilitates long-term awakening of the host's immune system, ultimately achieving enhanced therapeutic effects. As an effective candidate for cancer immunotherapy, nanogel-based immunotherapy has been widely used. In this review, we mainly summarize the recent advances of nanogel-based immunotherapy to deliver immunomodulatory small molecule drugs, antibodies, genes and cytokines, to target antigen presenting cells, form cancer vaccines, and enable chimeric antigen receptor (CAR)-T cell therapy. Future challenges as well as expected and feasible prospects for clinical treatment are also highlighted.

Cell Coding Arrays Based on Fluorescent Glycan Nanoparticles for Cell Line Identification and Cell Contamination Evaluation

Cell lines are applied on a large scale in the field of biomedicine, but they are susceptible to issues such as misidentification and cross-contamination. This situation is becoming worse over time due to the rapid growth of the biomedical field, and thus there is an urgent need for a more effective strategy to address the problem. As described herein, a cell coding method is established based on two types of uniform and stable glycan nanoparticles that are synthesized using the graft-copolymerization-induced self-assembly (GISA) method, which further exhibit distinct fluorescent properties due to elaborate modification with fluorescent labeling molecules. The different affinity between each nanoparticle and various cell lines results in clearly distinguishable differences in their endocytosis degrees, thus resulting in distinct characteristic fluorescence intensities. Through flow cytometry measurements, the specific signals of each cell sample can be recorded and turned into a map divided into different regions by statistical processing. Using this sensing array strategy, we have successfully identified six human cell lines, including one normal type and five tumor types. Moreover, cell contamination evaluation of different cell lines with HeLa cells as the contaminant in a semiquantitative analysis has also been successfully achieved. Notably, the whole process of nanoparticle fabrication and fluorescent testing is facile and the results are highly reliable.

Targeted Delivery of Drugs and Genes Using Polymer Nanocarriers for Cancer Therapy

Cancer is one of the primary causes of worldwide human deaths. Most cancer patients receive chemotherapy and radiotherapy, but these treatments are usually only partially efficacious and lead to a variety of serious side effects. Therefore, it is necessary to develop new therapeutic strategies. The emergence of nanotechnology has had a profound impact on general clinical treatment. The application of nanotechnology has facilitated the development of nano-drug delivery systems (NDDSs) that are highly tumor selective and allow for the slow release of active anticancer drugs. In recent years, vehicles such as liposomes, dendrimers and polymer nanomaterials have been considered promising carriers for tumor-specific drug delivery, reducing toxicity and improving biocompatibility. Among them, polymer nanoparticles (NPs) are one of the most innovative methods of non-invasive drug delivery. Here, we review the application of polymer NPs in drug delivery, gene therapy, and early diagnostics for cancer therapy.

High-Order Assembly toward Polysaccharide-Based Complex Coacervate Nanodroplets Capable of Targeting Cancer Cells

High-order assembly plays a significant role in the formation of living organisms containing a large number of biomacromolecules and, thus, enlightens the construction of nanomaterials that can load macromolecular payloads at a high efficiency. Herein, by choosing anionic hyaluronic acid (HA) as a model payload, we demonstrated how the electrostatic-interaction-induced high-order assembly can be used to load efficiently biomacromolecules into complex coacervate nanodroplets. The resultant assemblies were primarily composed of HA and cationic chitosan oligosaccharide/dextran (COS/Dex) nanogels and had a controllable structure while also exhibiting biological functionality. HA in the assemblies is capable of targeting CD44-overexpressed tumor cells through CD44-mediated endocytic pathways, which are elucidated herein. Therefore, this study provides a reliable approach for the efficient loading of macromolecular payloads into complex coacervate nanodroplets via electrostatic-attraction-induced high-order assembly.

Bio-inspired gene carriers with low cytotoxicity constructed via the assembly of dextran nanogels and nano-coacervates

Aim: To achieve safe and biocompatible gene carriers. Materials & methods: A core/shell-structured hierarchical carrier with an internal peptide/gene coacervate 'core' and a dextran nanogel 'shell' on the surface has been designed. Results: The dextran nanogels shield coacervate (DNSC) can effectively condense genes and release them in reducing environments. The dextran nanogel-based 'shell' can effectively shield the positive charge of the peptide/gene coacervate 'core', thus reducing the side effects of cationic gene carriers. In contrast with the common nonviral gene carriers that had high cytotoxicities, the DNSC showed a high transfection efficiency while maintaining a low cytotoxicity. Conclusion: The DNSC provides an effective environmentally responsive gene carrier with potential applications in the fields of gene therapy and gene carrier development.

Dextran-based coacervate nanodroplets as potential gene carriers for efficient cancer therapy

The intractable toxicity of cationic polymers limits their applicability in gene transport and controlled release. In consideration of the good biocompatibility and biofunctionality of dextran, herein we design and synthesize two types of amino group-containing cationic copolymers based on dextran by the copolymerization of cationic monomers from dextran backbones. Additionally, allyl crosslinkers containing disulfide bonds were introduced into polymerization, that made the copolymer crosslinked by disulfide. The resultant coacervates were formed from the self-assembly of cationic coplymers and anionic genes, and redox-responsive disulfide branch points endow coacervates with reducing environment responsiveness. The in vitro experiments showed that the dextran-based coacervates were sensitive to the reducing environment and underwent cleavage, which resulted in an effective release, uptake, and transfection of the genes by 293T cells. In addition, dextran-based coacervates can be used to carry siRNA into cancer cells with a high transfection efficiency, demonstrating their potential applicability in treatment against cancer.

Gene/paclitaxel co-delivering nanocarriers prepared by framework-induced self-assembly for the inhibition of highly drug-resistant tumors

While drug resistance has been recognized as the main cause of unsuccessful chemotherapy, the efficient inhibition of highly drug-resistant tumors still remains a significant challenge, especially for in vivo treatments. Drug resistance has been associated with the high expression of the multi-drug resistance gene 1 (MDR1), which can encode an efflux transporter known as P-glycoprotein (P-gp) that is located in the cellular membrane. Therefore, the combined delivery of MDR1-inhibited genes and chemotherapeutic drugs is anticipated to enable the effective inhibition of drug-resistant tumors. Herein, highly paclitaxel (PTX)-resistant ovarian (OV) cancer with a drug resistance index reaching up to ~ 60 was chosen to evaluate the performance of an efficient gene/drug co-delivery nanocarrier. Inspired by the self-assembly that occurs in cells and exosomes, we designed a biomimetic lipid/dextran hybrid nanocarrier with a diameter of ~ 100 nm to enhance the endocytosis and the efficiency of drug/gene release within the cells. This nanocarrier was fabricated via the frame-guided self-assembly of lipid amphiphiles on the surfaces of redox-cleavable dextran-based nanogels. The anionic MDR1-siRNA and the hydrophobic drug PTX were respectively loaded into the cationic lipid shell and the hydrophobic internal core of the hybrid nanocarriers. MDR1-siRNA can knock down MDR1, promoting the accumulation of PTX in cells, and thus is expected to achieve an efficient inhibitory effect against highly PTX-resistant cancer cells. Both in vitro and in vivo studies revealed that this dual-delivery system significantly enhanced the therapeutic effect in comparison with that provided by a PTX-only system. Thus, the construction of gene/chemo co-delivered lipid/dextran nanocarriers provides a new strategy to inhibit highly drug-resistant tumors both in vitro and in vivo. In addition, this work will contribute toward the development of urgently needed tumor nanotherapy that is able to overcome drug resistance while also offering an unmatched range of effective therapeutic nanocarriers. STATEMENT OF SIGNIFICANCE: The biomimetic lipid/dextran hybrid nanocarrier with a diameter of ~ 100 nm, which was fabricated via the frame-guided self-assembly of lipid amphiphiles onto the surface of redox-cleavable dextran-based nanogels, provides a model carrier to co-deliver MDR1-siRNA and PTX.  The MDR1-siRNA/PTX co-loaded biomimetic lipid/dextran hybrid nanocarriers demonstrate good capability in overcoming the PTX-resistance in highly chemo-resistant human ovarian (OV) cancer cells both in vitro and in vivo.

Fluorescent Polysaccharide Nanogels for the Detection of Tumor Heterogeneity in Drug-Surviving Cancer Cells

Tumor metastasis, recurrence, and drug resistance have been associated with tumor heterogeneity, and thus the identification of tumor heterogeneity has great significance in medicine. The approach provides a way to identify and isolate various cell subtypes from drug-surviving ovarian cancer cells, by synthesizing a series of polysaccharide nanogels and using them in flow cytometry analysis. The results show that the drug-surviving OVCAR-3 cells that are subjected to paclitaxel intervention comprise various cell subtypes, including drug-resistant and non-drug-resistant cell subtypes. Besides, there are significant differences between the drug-resistant cell subtype and non-drug-resistant cell subtype in terms of their migration and invasion behavior. In addition, the phenotype switch genes are detected by mRNA sequencing, and it is found that different subtypes show significant genetic differences with regard to their drug resistance, metastasis, and proliferation. In particular, modifying polysaccharide nanogels with lipids can promote the uptake of nanogels by drug-resistant cells, and thus the lipid modification can enhance the effectiveness of a chemotherapy drug carrier against drug-resistant cells. These studies reveal the heterogeneity of drug-surviving tumor cells, as well as the significant differences in drug-resistance, migration, and invasion capabilities of different subtypes, and demonstrate a way to overcome drug resistance.

Novel Hybrid Dextran-Gadolinium Nanoparticles as High-relaxivity T1 Magnetic Resonance Imaging Contrast Agent for Mapping the Sentinel Lymph Node

OBJECTIVES

To assess the applicability of a novel hybrid dextran-gadolinium nanoparticles (NPs) as high-relaxivity T1 magnetic resonance imaging (MRI) contrast agent for mapping the sentinel lymph node (SLN).

METHODS

Dextran-bis-acrylamide-polyacrylic acid (Dex-MBA-PAA) NPs were synthesized through a self-assembly assisted approach and complexed with multiple chelated gadolinium (Gd) (III) ions. After their characterization was validated, they were used to mapping SLNs by MRI in Wistar rats, and their biosafety was evaluated.

RESULTS

Dextran-MBA-polyacrylic acid-Gd NPs have suitable particle size and much higher longitudinal relaxivity (r1) than that of commonly used clinical MRI contrast agents (eg, gadopentetic acid dimeglumine salt injection). The in vivo T1-weighted MRI results revealed their effectiveness at mapping SLNs. And their biological safety was also verified.

CONCLUSIONS

Dextran-MBA-polyacrylic acid-Gd NPs were synthesized and validated by in vitro and in vivo experiments for their ability to visualize SLNs by MRI with accurate positioning and excellent biosafety, and they have great potential for clinical SLN mapping.

A Nanoprobe for Diagnosing and Mapping Lymphatic Metastasis of Tumor Using 3D Multispectral Optoacoustic Tomography Owing to Aggregation/Deaggregation Induced Spectral Change

Lymphatic metastasis of tumor is one of leading causes of cancer‐related death, and diagnosing lymphatic metastasis is of significance in terms of optimal disease management and possible better outcomes for patients. Herein a turn‐on optoacoustic nanoprobe is reported for noninvasively diagnosing and locating lymphatic metastasis in vivo. A positively charged tricyanofuran‐containing polyene chromophore (TCHM) with high extinction coefficient is designed, synthesized, and allowed to form the nanoprobe with a negatively charged hyaluronan. The TCHMs take an aggregated state within the nanoprobe and exhibit weak absorption at 882 nm, the overexpressed hyaluronidase in cancer cells specifically degrades hyaluronan into small fragments and disaggregates TCHMs, thereby greatly enhancing the absorption at 882 nm and generating prominent optoacoustic signals. For multispectral optoacoustic tomography (MSOT) imaging in vivo, mice models with subcutaneous tumor and orthotopic bladder tumor are imaged first to demonstrate the nanoprobe's capability for detecting HAase‐overexpressing tumors. A mouse model of lymphatic metastasis of tumor is then established and the lymphatic metastasis is successfully imaged and tracked optoacoustically. The imaging results were verified using multiple biochemical assays. Moreover, 3D MSOT renderings are obtained for precisely locating and tracking the metastasis of tumor in lymphatic system in a spatiotemporal manner.

Doxorubicin-loaded dextran-based nano-carriers for highly efficient inhibition of lymphoma cell growth and synchronous reduction of cardiac toxicity

Purpose

Cardiac side effects of doxorubicin (Dox) have limited its clinical application. The aim of this study was to explore new Dox-loaded dextran-based nano-carriers (NCs) in efficiently targeting tumor growth with less cardiac toxicity.

Methods

Inspired by recent reports that polymeric NCs could function as sustained, controlled and targeted drug delivery systems, we developed Dox-loaded NCs which displayed a 2-fold release ratio of Dox in the mimic tumor site condition (pH 5.0 with 10 mM glutathione, GSH) as much as that in systemic circulation condition (pH 7.4).

Results

Lymphoma cells treated with Dox-NCs had significantly higher intracellular Dox concentrations and more apoptotic induction, with lower P-gp expression, when compared with those treated with Dox alone. The identified mechanism of action, apoptosis, was triggered through survivin reduction and caspase-3 activation. Even in the Dox-resistant cells, Dox-NCs could significantly inhibit cell growth and induce apoptosis. In murine lymphoma xenograft models, Dox-NCs also remarkably significantly retarded tumor growth, assessed by murine weight, and demonstrated less cytotoxicity. Noticeably, apoptotic myocardial cells were decreased in the Dox-NCs-treated group, when compared with the control group, which was consistent with low intracellular Dox concentration in the cardiac cell line H9C2.

Conclusion

Dox-NCs showed an anti-lymphoma effect with reduced cardiac toxicity in both in vivo and in vitro models and, therefore, could be a potential therapeutic agent in the treatment of lymphoma.

Scalable and cleavable polysaccharide nanocarriers for the delivery of chemotherapy drugs

While polysaccharide-based nanocarriers have been recognized for their crucial roles in tumor theranostics, the industrial-scale production of nanotherapeutics still remains a significant challenge. Most current approaches adopt a postpolymerization self-assembly strategy that follows a separate synthetic step and thus suffers from subgram scale yields and a limited range of application. In this study, we demonstrate the kilogram-scale formation of polysaccharide-polyacrylate nanocarriers at concentrations of up to 5 wt% through a one-pot approach - starting from various acrylate monomers and polysaccharides - that combines aspects of hydrophobicity-induced self-assembly with the free radical graft copolymerization of acrylate monomers from polysaccharide backbones into a single process that is thus denoted as a graft copolymerization induced self-assembly. We also demonstrate that this novel approach is applicable to a broad range of polysaccharides and acrylates. Notably, by choosing a crosslinker that bears a disulfide group and two vinyl capping groups to structurally lock the nanocarriers, the products are rendered cleavable in the reducing environments encountered at tumor sites and thus provide ideal candidates for the construction of anticancer nanotherapeutic systems. In vitro and in vivo studies demonstrated that the use of this nanocarrier for the delivery of doxorubicin hydrochloride (DOX) significantly decreased the side effects of DOX and improved the bio-safety of the chemotherapy accordingly.

STATEMENT OF SIGNIFICANCE

While polysaccharide-based nanocarriers have been recognized for their crucial roles in tumor theranostics, the industrial-scale production of these nanotherapeutics still remains a significant challenge. Most current approaches adopt a post-polymerization self-assembly strategy which that follows a separate synthetic step, and thus suffers from sub-gram scale yields and a limited range of application. In this study, the hydrophobic effect was combined with free radical polymerization to facilitate the graft copolymerization-induced self-assembly (GISA) of acrylate monomers with various hydrophobicities to construct cleavable polysaccharide-polyacrylate nanocarriers at a high efficiency with excellent potential for industrial-scale production. We envision that these nanocarriers will contribute to the development of tumor nanotheranostics that combine the biological functionalities of polysaccharides with the unmatched application-specific flexibility of nanocarriers.

Gap-enhanced Raman tags for high-contrast sentinel lymph node imaging

The sentinel lymph node (SLN) biopsy is gaining in popularity as a procedure to investigate the lymphatic metastasis of malignant tumors. The commonly used techniques to identify the SLNs in clinical practice are blue dyes-guided visualization, radioisotope-based detection and near-infrared fluorescence imaging. However, all these methods have not been found to perfectly fit the clinical criteria with issues such as short retention time in SLN, poor spatial resolution, autofluorescence, low photostability and high cost. In this study, we have reported a new type of nanoprobes, named, gap-enhanced Raman tags (GERTs) for the SLN Raman imaging. With the advantageous features including unique "fingerprint" Raman signal, strong Raman enhancement, high photostability, good biocompatibility and extra-long retention time, we have demonstrated that GERTs are greatly favorable for high-contrast and deep SLN Raman imaging, which meanwhile reveals the dynamic migration behavior of the probes entering the SLN. In addition, a quantitative volumetric Raman imaging (qVRI) data-processing method is employed to acquire a high-resolution 3-dimensional (3D) margin of SLN as well as the content variation of GERTs in the SLN. Moreover, SLN detection could be realized via a cost-effective commercial portable Raman scanner. Therefore, GERTs hold the great potential to be translated in clinical application for accurate and intraoperative location of the SLN.

The Potential of Stimuli-Responsive Nanogels in Drug and Active Molecule Delivery for Targeted Therapy

Nanogels (NGs) are currently under extensive investigation due to their unique properties, such as small particle size, high encapsulation efficiency and protection of active agents from degradation, which make them ideal candidates as drug delivery systems (DDS). Stimuli-responsive NGs are cross-linked nanoparticles (NPs), composed of polymers, natural, synthetic, or a combination thereof that can swell by absorption (uptake) of large amounts of solvent, but not dissolve due to the constituent structure of the polymeric network. NGs can undergo change from a polymeric solution (swell form) to a hard particle (collapsed form) in response to (i) physical stimuli such as temperature, ionic strength, magnetic or electric fields; (ii) chemical stimuli such as pH, ions, specific molecules or (iii) biochemical stimuli such as enzymatic substrates or affinity ligands. The interest in NGs comes from their multi-stimuli nature involving reversible phase transitions in response to changes in the external media in a faster way than macroscopic gels or hydrogels due to their nanometric size. NGs have a porous structure able to encapsulate small molecules such as drugs and genes, then releasing them by changing their volume when external stimuli are applied.

One-pot synthesis of dextran-coated iron oxide nanoclusters for real-time regional lymph node mapping

The intraoperative precision cleaning of lymph nodes (LNs) is an essential component of treating neoplastic disease. To develop efficient probes for the targeted detection of LNs that could act as carriers for the specific diagnosis and treatment of metastatic LNs in the future, dextran-coated iron oxide nanoclusters (DIONs) were synthesized using a one-pot coprecipitation procedure. These modified DIONs have good water dispersibility, cytocompatibility, an optimum size, and a stable, dark brown color for LN imaging. In this study, cytotoxicity was evaluated using lymphatic endothelial cells (LECs) to predict biosafety and biocompatibility. Most importantly, the effectiveness of DIONs in mapping perigastric LNs in Sprague Dawley rats following injection into the gastric submucosal layer was demonstrated. In addition, a long-term tracing in vivo (from 4 days to 3 months) indicated that the DIONs had good biosafety and biocompatibility according to an evaluation of the behavior and blood biochemistry of the rat and a histopathological examination of the important organs.

Self-Assembly Assisted Fabrication of Dextran-Based Nanohydrogels with Reduction-Cleavable Junctions for Applications as Efficient Drug Delivery Systems

In order to overcome the key challenge in improving both fabrication efficiency and their drug delivery capability of anti-cancer drug delivery systems (ACDDS), here polyacrylic acid (PAA) grafted dextran (Dex) nanohydrogels (NGs) with covalent crosslinked structure bearing redox sensitive disulfide crosslinking junctions (Dex-SS-PAA) were synthesized efficiently through a one-step self-assembly assisted methodology (SAA). The Dex-SS-PAA were subsequently conjugated with doxorubicin through an acid-labile hydrazone bond (Dex-SS-PAA-DOX). The in vitro drug release behavior, anti-cancer effects in vivo, and biosafety of the as-prepared acid- and redox-dual responsive biodegradable NGs were systematically investigated. The results revealed that the Dex-SS-PAA-DOX exhibited pH- and redox-controlled drug release, greatly reduced the toxicity of free DOX, while exhibiting a strong ability to inhibit the growth of MDA-MB-231 tumors. Our study demonstrated that the Dex-SS-PAA-DOX NGs are very promising candidates as ACDDS for anti-cancer therapeutics.

Nanogels: An overview of properties, biomedical applications and obstacles to clinical translation

Nanogels have emerged as a versatile hydrophilic platform for encapsulation of guest molecules with a capability to respond to external stimuli that can be used for a multitude of applications. These are soft materials capable of holding small molecular therapeutics, biomacromolecules, and inorganic nanoparticles within their crosslinked networks, which allows them to find applications for therapy as well as imaging of a variety of disease conditions. Their stimuli-responsive behavior can be easily controlled by selection of constituent polymer and crosslinker components to achieve a desired response at the site of action, which imparts nanogels the ability to participate actively in the intended function of the carrier system rather than being passive carriers of their cargo. These properties not only enhance the functionality of the carrier system but also help in overcoming many of the challenges associated with the delivery of cargo molecules, and this review aims to highlight the distinct and unique capabilities of nanogels as carrier systems for the delivery of an array of cargo molecules over other nanomaterials. Despite their obvious usefulness, nanogels are still not a commonplace occurrence in clinical practice. We have also made an attempt to highlight some of the major challenges that need to be overcome to advance nanogels further in the field of biomedical applications.

Biodegradable Smart Nanogels: A New Platform for Targeting Drug Delivery and Biomedical Diagnostics

Nanogels (or nanohydrogels) have been extensively investigated as one of the most promising nanoparticulate biomedical platforms owing to their advantageous properties that combine the characteristics of hydrogel systems with nanoparticles. Among them, smart nanogels that have the ability to respond to external stimuli, such as pH, redox, temperature, enzymes, light, magnetic field and so forth, are most attractive in the area of drug delivery. Besides, numerous multifunctionalized nanogels with high sensitivity and specificity were designed for diagnostic applications. In this feature article, we have reviewed and discussed the recent progress of biodegradable nanogels as smart nanocarriers of anticancer drugs and biomedical diagnostic agents for cancer.

Nanogels as imaging agents for modalities spanning the electromagnetic spectrum

In the past few decades, advances in imaging equipment and protocols have expanded the role of imaging in in vivo diagnosis and disease management, especially in cancer. Traditional imaging agents have rapid clearance and low specificity for disease detection. To improve accuracy in disease identification, localization and assessment, novel nanomaterials are frequently explored as imaging agents to achieve high detection specificity and sensitivity. A promising material for this purpose are hydrogel nanoparticles, whose high hydrophilicity, biocompatibility, and tunable size in the nanometer range make them ideal for imaging. These nanogels (10 to 200 nm) can circumvent uptake by the reticuloendothelial system, allowing longer circulation times than small molecules. In addition, their size/surface properties can be further tailored to optimize their pharmacokinetics for imaging of a particular disease. Herein, we provide a comprehensive review of nanogels as imaging agents in various modalities with sources of signal spanning the electromagnetic spectrum, including MRI, NIR, UV-vis, and PET. Many materials and formulation methods will be reviewed to highlight the versatility of nanogels as imaging agents.

Non-invasive monitoring of transplanted endothelial progenitor cells in diabetic ischemic stroke models

Endogenous endothelial progenitor cells (EPCs) are functionally impaired in hyperglycemia through the p38 MAPK signaling pathway. However, the number and function of transplanted exogenous EPCs in diabetic animals remains unclear. The objectives of this study were to establish a non-invasive imaging strategy to monitor the homing of transplanted EPCs in diabetic stroke mice and to assess the effect of RWJ 67657, an inhibitor of p38 MAPK, on the homing ability of exogenous EPCs. Bone marrow-derived EPCs were labeled in vitro with a multi-functional nanoprobe modified with paramagnetic chelators and fluorophores before being infused into stroke mice. The signal of the nanoprobe reached its peak on day 5 in both magnetic resonance imaging and near-infrared fluorescence imaging after EPC transplantation in wild-type stroke models. The signal enhancement of diabetic stroke models was significantly lower than that of wild-type controls. However, the signal intensity of diabetic stroke models significantly increased after oral administration of RWJ 67657, indicating that more transplanted EPCs migrated to the ischemic brain. Furthermore, the increased exogenous EPCs induced remarkably greater angiogenesis after stroke. These results suggest that this dual-modal imaging strategy is feasible for non-invasively monitoring transplanted cells in vivo.