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

3D Printing of Polysaccharide-Based Hydrogel Scaffolds for Tissue Engineering Applications: A Review

In tissue engineering, 3D printing represents a versatile technology employing inks to construct three-dimensional living structures, mimicking natural biological systems. This technology efficiently translates digital blueprints into highly reproducible 3D objects. Recent advances have expanded 3D printing applications, allowing for the fabrication of diverse anatomical components, including engineered functional tissues and organs. The development of printable inks, which incorporate macromolecules, enzymes, cells, and growth factors, is advancing with the aim of restoring damaged tissues and organs. Polysaccharides, recognized for their intrinsic resemblance to components of the extracellular matrix have garnered significant attention in the field of tissue engineering. This review explores diverse 3D printing techniques, outlining distinctive features that should characterize scaffolds used as ideal matrices in tissue engineering. A detailed investigation into the properties and roles of polysaccharides in tissue engineering is highlighted. The review also culminates in a profound exploration of 3D polysaccharide-based hydrogel applications, focusing on recent breakthroughs in regenerating different tissues such as skin, bone, cartilage, heart, nerve, vasculature, and skeletal muscle. It further addresses challenges and prospective directions in 3D printing hydrogels based on polysaccharides, paving the way for innovative research to fabricate functional tissues, enhancing patient care, and improving quality of life.

Marine Microbial Polysaccharides: An Untapped Resource for Biotechnological Applications

As the largest habitat on Earth, the marine environment harbors various microorganisms of biotechnological potential. Indeed, microbial compounds, especially polysaccharides from marine species, have been attracting much attention for their applications within the medical, pharmaceutical, food, and other industries, with such interest largely stemming from the extensive structural and functional diversity displayed by these natural polymers. At the same time, the extreme conditions within the aquatic ecosystem (e.g., temperature, pH, salinity) may not only induce microorganisms to develop a unique metabolism but may also increase the likelihood of isolating novel polysaccharides with previously unreported characteristics. However, despite their potential, only a few microbial polysaccharides have actually reached the market, with even fewer being of marine origin. Through a synthesis of relevant literature, this review seeks to provide an overview of marine microbial polysaccharides, including their unique characteristics. In particular, their suitability for specific biotechnological applications and recent progress made will be highlighted before discussing the challenges that currently limit their study as well as their potential for wider applications. It is expected that this review will help to guide future research in the field of microbial polysaccharides, especially those of marine origin.

Effective mRNA Delivery by Condensation with Cationic Nanogels Incorporated into Liposomes

The challenge in effective delivery of mRNA has been a major hurdle in their development as therapeutics. Herein, we present that the incorporation of cationic nanogels as the condensing material for mRNA into liposomes enables stable and enhanced mRNA delivery to cells in vitro. We prepared dextran-based nanogel particles, which were surface functionalized with oligoarginine peptide (DNPR9) and complexed with mRNA for incorporation into liposomes (LipoDNPR9). The use of DNPR9 with the liposomes resulted in enhanced internalization, as well as a 4-fold increase in transfection of luciferase mRNA when treated with A549 cells in vitro, compared to control liposomes. The enhancement in transfection efficiency was also observed in various cell lines while causing low cytotoxicity. The versatility of the strategy was also investigated by applying DNPR9 for mRNA condensation to ionizable lipid particles, which resulted in an ∼55% increase in transfection. The current development based on nanogel-incorporated liposomes introduces an effective platform for mRNA delivery, while the condensation strategy using DNPR9 can be widely applied for various lipid-based formulations to enhance their efficacy.

Carbohydrates Used in Polymeric Systems for Drug Delivery: From Structures to Applications

Carbohydrates, one of the most important compounds in living organisms, perform numerous roles, including those associated with the extracellular matrix, energy-related compounds, and information. Of these, polymeric carbohydrates are a class of substance with a long history in drug delivery that have attracted more attention in recent years. Because polymeric carbohydrates have the advantages of nontoxicity, biocompatibility, and biodegradability, they can be used in drug targeting, sustained drug release, immune antigens and adjuvants. In this review, various carbohydrate-based or carbohydrate-modified drug delivery systems and their applications in disease therapy have been surveyed. Specifically, this review focuses on the fundamental understanding of carbohydrate-based drug delivery systems, strategies for application, and the evaluation of biological activity. Future perspectives, including opportunities and challenges in this field, are also discussed.

Strategic Design of Intelligent-Responsive Nanogel Carriers for Cancer Therapy

Owing to the distinctive constituents of tumor tissue from those healthy organs, nanomedicine strategies show significant potentials in smart drug delivery. Nowadays, stimuli-responsive nanogels are playing increasingly important roles in the application of cancer therapy because of their sensitivity to various internal or external physicochemical stimuli, which exhibit site-specific and markedly enhanced drug release. Besides, nanogels are promising as drug carriers because of their porous structures, good biocompatibility, large surface area, and excellent capability with drugs. Taking advantage of multiresponsiveness, recent years have witnessed the rapid evolution of stimulus-responsive nanogels from monoresponsive to multiresponsive systems; however, there lacks a comprehensive review summarizing these reports. In this Review, we discuss the properties, synthesis, and characterization of nanogels. Moreover, tumor microenvironment and corresponding designing strategies for stimuli-response nanogels, both exogenous (temperature, magnetic field, light) and endogenous (pH, biomolecular, redox, ROS, pressure, hypoxia) are summarized on the basis of the recent advances in multistimuli-responsive nanogel systems. Nanogel and two-dimensional material composites show excellent performance in the field of constructing multistimulus-responsive nanoparticles and precise intelligent drug release integrated system for multimodal cancer diagnosis and therapy. Finally, potential progresses and suggestions are provided for the further design of hybrid nanogels based on emerging two-dimensional materials.

A nanoselenium-coating biomimetic cytomembrane nanoplatform for mitochondrial targeted chemotherapy- and chemodynamic therapy through manganese and doxorubicin codelivery

The cell membrane is widely considered as a promising delivery nanocarrier due to its excellent properties. In this study, self-assembled Pseudomonas geniculate cell membranes were prepared with high yield as drug nanocarriers, and named BMMPs. BMMPs showed excellent biosafety, and could be more efficiently internalized by cancer cells than traditional red cell membrane nanocarriers, indicating that BMMPs could deliver more drug into cancer cells. Subsequently, the BMMPs were coated with nanoselenium (Se), and subsequently loaded with Mn²⁺ ions and doxorubicin (DOX) to fabricate a functional nanoplatform (BMMP-Mn²⁺/Se/DOX). Notably, in this nanoplatform, Se nanoparticles activated superoxide dismutase-1 (SOD-1) expression and subsequently up-regulated downstream H₂O₂ levels. Next, the released Mn²⁺ ions catalyzed H₂O₂ to highly toxic hydroxyl radicals (·OH), inducing mitochondrial damage. In addition, the BMMP-Mn²⁺/Se nanoplatform inhibited glutathione peroxidase 4 (GPX4) expression and further accelerated intracellular reactive oxygen species (ROS) generation. Notably, the BMMP-Mn²⁺/Se/DOX nanoplatform exhibited increased effectiveness in inducing cancer cell death through mitochondrial and nuclear targeting dual-mode therapeutic pathways and showed negligible toxicity to normal organs. Therefore, this nanoplatform may represent a promising drug delivery system for achieving a safe, effective, and accurate cancer therapeutic plan.

Investigation of Polyacrylic Acid Toxicity in Human Breast Cancer (MCF-7) and Mouse Fibroblast (L-929) Cell Lines

In recent years, biopolymers have been widely used in various fields of medicine. Before using any polymer, its biocompatibility should be examined. Polyacrylic acid (PAA), a polyelectrolyte, is known to be used as an adjuvant effect in immunology, anti-thrombogenic effect in medical experiments, and as a carrier in drug delivery systems. Although there are studies on various conjugates and nanoparticles of PAA, studies on its toxicity alone are limited. Determination of toxicity in biopolymer studies is extremely important. Cultures of various cells are used for toxicity analyses. This study aimed to investigate the toxicity of PAA in human breast cancer (MCF-7) and mouse fibroblast (L-929) cell lines by various methods. Cell culture, 3-(4,5-dimethyltriazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), trypan blue and 4,6-diamidino 2 phenylindole (DAPI) methods were used in the study. The half-maximal effective concentration (EC50) value of PAA was 6.6 mg/ml in MCF 7 cells and 1.8 mg/ ml in L-929 cells. Apoptosis was observed in cells on the increasing PAA concentration with DAPI. With these results, the cytotoxic properties of PAA were determined in vitro. Accordingly, the biocompatibility of polymers to be used in modeling should be supported by in vitro and in vivo studies.

Combining Dextran Conjugates with Stimuli-Responsive and Folate-Targeting Activity: A New Class of Multifunctional Nanoparticles for Cancer Therapy

Nanoparticles with active-targeting and stimuli-responsive behavior are a promising class of engineered materials able to recognize the site of cancer disease, targeting the drug release and limiting side effects in the healthy organs. In this work, new dual pH/redox-responsive nanoparticles with affinity for folate receptors were prepared by the combination of two amphiphilic dextran (DEX) derivatives. DEXFA conjugate was obtained by covalent coupling of the polysaccharide with folic acid (FA), whereas DEXssPEGCOOH derived from a reductive amination step of DEX was followed by condensation with polyethylene glycol 600. After self-assembling, nanoparticles with a mean size of 50 nm, able to be destabilized in acidic pH and reducing media, were obtained. Doxorubicin was loaded during the self-assembling process, and the release experiments showed the ability of the proposed system to modulate the drug release in response to different pH and redox conditions. Finally, the viability and uptake experiments on healthy (MCF-10A) and metastatic cancer (MDA-MB-231) cells proved the potential applicability of the proposed system as a new drug vector in cancer therapy.

Prospects of Delivering Natural Compounds by Polymer-Drug Conjugates in Cancer Therapeutics

Synthetic chemotherapeutics have played a crucial role in minimizing mostly palliative symptoms associated with cancer; however, they have also created other problems such as system toxicity due to a lack of specificity. This has led to the development of polymer-drug conjugates amongst other novel drug delivery systems. Most of the formulations designed using delivery systems consist of synthetic drugs and face issues such as drug resistance, which has already rendered drugs such as antibiotics ineffective. This is further exacerbated by toxicity due to long term use. Given these problems and the fact that conjugation of synthetic compounds to polymers has been relatively slow with no formulation on the market after a decade of extensive studies, the focus has shifted to using this platform with medicinal plant extracts to improve solubility, specificity and increase drug release of medicinal and herbal bioactives. In recent years, various plant extracts such as flavonoids, tannins and terpenoids have been studied extensively using this approach. The success of formulations developed using novel drug-delivery systems is highly dependent on the tumour microenvironment especially on the enhanced permeability and retention effect. As a result, the compromised lymphatic network and 'leaky' vasculature exhibited by tumour cells act as a guiding principle in the delivering of these formulations. This review focuses on the state of the polymer-drug conjugates and their exploration with natural compounds, the progress and difficulties thus far, and future directions concerning cancer treatment.

pH-Sensitive nanogels for drug delivery in cancer therapy

Compared to normal tissue, solid tumors exhibit a lower pH value. Such pH gradient can be used to design pH-sensitive nanogels for selective drug delivery. The acid-sensitive elements in the nanogel cause it to swell/degrade rapidly, followed by rapid drug release.

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.

Glycogen as an advantageous polymer carrier in cancer theranostics: Straightforward in vivo evidence

As a natural polysaccharide polymer, glycogen possesses suitable properties for use as a nanoparticle carrier in cancer theranostics. Not only it is inherently biocompatible, it can also be easily chemically modified with various moieties. Synthetic glycogen conjugates can passively accumulate in tumours due to enhanced permeability of tumour vessels and limited lymphatic drainage (the EPR effect). For this study, we developed and examined a glycogen-based carrier containing a gadolinium chelate and near-infrared fluorescent dye. Our aim was to monitor biodistribution and accumulation in tumour-bearing rats using magnetic resonance and fluorescence imaging. Our data clearly show that these conjugates possess suitable imaging and tumour-targeting properties, and are safe under both in vitro and in vivo conditions. Additional modification of glycogen polymers with poly(2-alkyl-2-oxazolines) led to a reduction in the elimination rate and lower uptake in internal organs (lower whole-body background: 45% and 27% lower MRI signals of oxazoline-based conjugates in the liver and kidneys, respectively compared to the unmodified version). Our results highlight the potential of multimodal glycogen-based nanopolymers as a carrier for drug delivery systems in tumour diagnosis and treatment.

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.

Scalable dextran-polypyrrole nano-assemblies with photothermal/photoacoustic dual capabilities and enhanced biocompatibility

Polypyrroles have shown great potential in photoacoustic imaging and photothermal therapy owing to its excellent photothermal conversion capabilities. However, the synthesis of polypyrrole-based nano-assemblies which have colloidal stability in biological buffers requires a number of steps, including the polymerization of pyrrole monomers, self-assembly of polypyrrole-based copolymers, and even an additional step to increase the biocompatibility of the nano-assemblies. Herein, a "polymerization/assembly" two-in-one synthesis is proposed for the first time to achieve the one-step synthesis of a new family of polypyrrole-based nano-assemblies, dextran-polypyrrole nano-assemblies (Dex-PPy NAs), under ambient conditions and in aqueous media. In addition, the approach employs tetravalent cerium ions as initiators which can initiate the polymerization of pyrrole monomers through the initiation of free radicals from dextran molecular chains. The resultant Dex-PPy NAs have a photothermal conversion efficiency reaching as high as 41 % and an excellent photostability. More importantly, the NAs with controllable nanoscale dimensions display no signs of cytotoxicity in both in vitro and in vivo studies owing to their biocompatible dextran "shell". An in vivo study further confirmed that the Dex-PPy NAs have excellent real-time photoacoustic imaging and photothermal therapy capabilities for malignant tumors. Therefore, this study represents an important step towards the scalable synthesis of polypyrrole-based nano-assemblies with photothermal/photoacoustic dual capabilities and enhanced biocompatibility.

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.

Nanoscale Self-Assembly for Therapeutic Delivery

Self-assembly is the process of association of individual units of a material into highly arranged/ordered structures/patterns. It imparts unique properties to both inorganic and organic structures, so generated, via non-covalent interactions. Currently, self-assembled nanomaterials are finding a wide variety of applications in the area of nanotechnology, imaging techniques, biosensors, biomedical sciences, etc., due to its simplicity, spontaneity, scalability, versatility, and inexpensiveness. Self-assembly of amphiphiles into nanostructures (micelles, vesicles, and hydrogels) happens due to various physical interactions. Recent advancements in the area of drug delivery have opened up newer avenues to develop novel drug delivery systems (DDSs) and self-assembled nanostructures have shown their tremendous potential to be used as facile and efficient materials for this purpose. The main objective of the projected review is to provide readers a concise and straightforward knowledge of basic concepts of supramolecular self-assembly process and how these highly functionalized and efficient nanomaterials can be useful in biomedical applications. Approaches for the self-assembly have been discussed for the fabrication of nanostructures. Advantages and limitations of these systems along with the parameters that are to be taken into consideration while designing a therapeutic delivery vehicle have also been outlined. In this review, various macro- and small-molecule-based systems have been elaborated. Besides, a section on DNA nanostructures as intelligent materials for future applications is also included.

Mitochondria and nucleus delivery of active form of 10-hydroxycamptothecin with dual shell to precisely treat colorectal cancer

AIM

The objective of this study was to deliver a ring-closed form of 10-hydroxycamptothecin (HCPT) to the mitochondria and nucleus to treat colorectal cancer.

MATERIALS & METHODS

HCPT-loaded nanoparticle HCPT@PLGA-PEG_2k-triphenylphosphonium/PLGA-hyd-PEG_4k-folic acid (PT/PHF) and HCPT@PT/PLGA-SS-PEG_4k-folic acid (PSF) were prepared by using emulsion-solvent evaporation method.

RESULTS

In vitro experimental results indicated HCPT@PT/PHF and HCPT@PT/PSF maintained a large amount of HCPT in active form, and delivered more HCPT to the nucleus and mitochondria of the tumor cell, which resulted in the enhancement of cytotoxicity of HCPT. In vivo experimental results indicated that HCPT@PT/PHF and HCPT@PT/PSF delivered more ring-closed form of HCPT to tumor tissue, which led to strong antitumor activity.

CONCLUSION

HCPT@PT/PHF and HCPT@PT/PSF could enhance therapeutic efficacy of HCPT to colorectal cancer.

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.

Smart pH responsive drug delivery system based on poly(HEMA-co-DMAEMA) nanohydrogel

The advent of smart nanohydrogel has revealed new opportunities for scientists to develop the most efficient anti-cancer vehicles with safe and biocompatible profile. In this experiment, using reversible addition-fragmentation chain transfer polymerization method as a novel, safe and smart pH responsive formulation of poly (hydroxyethyl methacrylate-co-N,N-dimethylaminoethyl methacrylate) and poly (ethylene glycol)-diacrylate as cross-linker were synthesized. The synthesized structure was confirmed by Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance methods. The pH responsive behavior of the synthesized particles was checked by size measurement in two different pH values (5.5 and 7.4) by dynamic light scattering and transmission electron microscopy. The prepared structure had nanometer sizes of 180 in medium with pH of 7.4, when it encountered acidic medium (e.g. pH 5.5), the particles swelled to about 400 nm. The efficiency of the prepared pH responsive nanohydrogels was tested as a drug delivery system. An anti-cancer drug, doxorubicin successfully interacted with this material. The release profiles of nanoparticles carrying drug molecules were checked in two different simulated pH of healthy organs (7.4) and tumor site (5.5). Despite lower release in pH of 7.4 (∼20%), an increased drug release of 80% was obtained in pH of 5.5. The in vitro toxicity assay, apoptosis evaluation and uptake experiments were performed on breast cancer cell line (MCF-7), which showed a time dependency cellular entrance, an enhanced cytotoxicity and apoptosis induction by the doxorubicin loaded nanoparticles. Hemolysis assays confirmed the safety and hemocompatibility of the developed nanohydrogel. The suitable size (<200 nm), pH responsive behavior, anti-proliferative activity and apoptosis induction in cancer cells and hemocompatibility were the noticeable features of the developed doxorubicin adsorbed nanoparticle, which introduced this formulation as an ideal vehicle in anti-cancer drug delivery.

Miscibility of poly(acrylic acid)/poly(methyl vinyl ketone) blend and in vitro application as drug carrier system

A series of poly(acrylic acid)/poly(methyl vinyl ketone) (PAA/PMVK) blends with different compositions were prepared by the solvent casting method. The miscibility of this pair of polymers was investigated by differential scanning calorimetry(DSC), Fourier transform infra-red (FTIR) and X-Ray diffraction (XRD) techniques. An in-vitro cytotoxicity test of the drug-carrier system via MTT (3-(4,5-demethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay revealed no significant cytotoxic effects at concentrations up to 100 µg· ml⁻¹. The STX/PAA-50 drug carrier systems were also prepared by solvent casting of solutions containing the sulfamethoxazole (STX) used as drug model and PAA/PMVK blend in N.N-dimethylformamide then crosslinked with acidified ethylene glycol. The release dynamic of STX from the prepared hydrogels was investigated in which the diffusion through the polymer matrix, the enhancement of the water solubility of STX, the influence of the initial drug concentration, the pH of the medium, and the effect of the degree of swelling of the polymer matrix on the release dynamic was evaluated. According to the total gastrointestinal transit time estimated by Belzer, the estimate distribution of STX released in the different organs indicated that the performance is obtained with the drug – carrier-system containing equal ratios of polymer and 10 wt% of STX (STX-10/PAA-50).

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.

Development of a thermosensitive protein conjugated nanogel for enhanced radio-chemotherapy of cancer

Although chemo-radiotherapy has been widely applied in clinics for cancer treatment, current strategies still face many challenges including serious side-effects and drug resistance. Herein, we develop a chemically cross-linked poly-N,N'-dimethyl aminoethyl methacrylate (PDMAEMA) smart nanogel as an excellent thermosensitive nanocarrier to load both an anticancer drug, doxorubicin (DOX) and a radioisotope, ¹³¹I-labeled albumin, for enhanced chemo-radioisotope therapy. Such a PDMAEMA nanogel in the solution form at room temperature can be easily injected into a tumor, in which it would be transformed into a gel at body temperature. Sustained drug release occurs in the tumor owing to the pH sensitive switching activity of the nanogel. In addition, the in situ thermogelling behavior of PDMAEMA leads to the long-term retention of ¹³¹I-labeled albumin within the tumor. In vivo chemo-radiotherapy is then conducted, achieving excellent therapeutic efficacy due to the sustained drug release and ¹³¹I retention for a long time in the cancer lesions. Our newly developed strategy of using a thermosensitive polymer for enhancing chemo-radiotherapy may be considered as a promising platform for combined cancer therapy without inducing obvious side-effects compared to the traditional chemo or radiotherapy.

Bioresponsive functional nanogels as an emerging platform for cancer therapy

INTRODUCTION

Bioresponsive nanogels with a crosslinked three-dimensional structure and an aqueous environment that undergo physical or chemical changes including swelling and dissociation in response to biological signals such as mild acidity, hyperthermia, enzymes, reducing agents, reactive oxygen species (ROS), and adenosine-5'-triphosphate (ATP) present in tumor microenvironments or inside cancer cells have emerged as an appealing platform for targeted drug delivery and cancer therapy.

AREAS COVERED

This review highlights recent designs and development of bioresponsive nanogels for facile loading and triggered release of chemotherapeutics and biotherapeutics. The in vitro and in vivo antitumor performances of drug-loaded nanogels are discussed.

EXPERT OPINION

Bioresponsive nanogels with an excellent stability and safety profile as well as fast response to biological signals are unique systems that mediate efficient and site-specific delivery of anticancer drugs, in particular macromolecular drugs like proteins, siRNA and DNA, leading to significantly enhanced tumor therapy compared with the non-responsive counterparts. Future research has to be directed to the development of simple, tumor-targeted and bioresponsive multifunctional nanogels, which can be either constructed from natural polymers with intrinsic targeting ability or functionalized with targeting ligands. We anticipate that rationally designed nanotherapeutics based on bioresponsive nanogels will become available for future clinical cancer treatment.

ABBREVIATIONS

AIE, aggregation-induced emission; ATP, adenosine-5'-triphosphate; ATRP, atom transfer radical polymerization; BSA, bovine serum albumin; CBA, cystamine bisacrylamide; CC, Cytochrome C; CDDP, cisplatin; CT, computed tomography; DC, dendritic cell; DiI, 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate; DOX, doxorubicin; dPG, dendritic polyglycerol; DTT, dithiothreitol; EAMA, 2-(N,N-diethylamino)ethyl methacrylate; EPR, enhanced permeability and retention; GrB, granzyme B; GSH, glutathione tripeptide; HA, hyaluronic acid; HAase, hyaluronidases; HCPT, 10-Hydroxycamptothecin; HEP, heparin; HPMC, hydroxypropylmethylcellulose; LBL, layer-by-layer; MTX, methotrexate; NCA, N-carboxyanhydride; OVA, ovalbumin; PAH, poly(allyl amine hydrochloride); PBA, phenylboronic acid; PCL, polycaprolactone; PDEAEMA, poly(2-diethylaminoethyl methacrylate); PDGF, platelet derived growth factor; PDPA, poly(2-(diisopropylamino)ethyl methacrylate); PDS, pyridyldisulfide; PEG, poly(ethylene glycol); PEGMA, polyethyleneglycol methacrylate; PEI, polyethyleneimine; PHEA, poly(hydroxyethyl acrylate); PHEMA, poly(2-(hydroxyethyl) methacrylate; PNIPAM, poly(N-isopropylacrylamide); PMAA, poly(methacrylic acid); PPDSMA, poly(2-(pyridyldisulfide)ethyl methacrylate); PTX, paclitaxel; PVA, poly(vinyl alcohol); QD, quantum dot; RAFT, reversible addition-fragmentation chain transfer; RGD, Arg-Gly-Asp peptide; ROP, ring-opening polymerization; ROS, reactive oxygen species; TMZ, temozolomide; TRAIL, tumor necrosis factor-related apoptosis inducing ligand; VEGF, vascular endothelial growth factor.

Carbon-based hybrid nanogels: a synergistic nanoplatform for combined biosensing, bioimaging, and responsive drug delivery

Nanosized crosslinked polymer networks, named as nanogels, are playing an increasingly important role in a diverse range of applications by virtue of their porous structures, large surface area, good biocompatibility and responsiveness to internal and/or external chemico-physical stimuli. Recently, a variety of carbon nanomaterials, such as carbon quantum dots, graphene/graphene oxide nanosheets, fullerenes, carbon nanotubes, and nanodiamonds, have been embedded into responsive polymer nanogels, in order to integrate the unique electro-optical properties of carbon nanomaterials with the merits of nanogels into a single hybrid nanogel system for improvement of their applications in nanomedicine. A vast number of studies have been pursued to explore the applications of carbon-based hybrid nanogels in biomedical areas for biosensing, bioimaging, and smart drug carriers with combinatorial therapies and/or theranostic ability. New synthetic methods and structures have been developed to prepare carbon-based hybrid nanogels with versatile properties and functions. In this review, we summarize the latest developments and applications and address the future perspectives of these carbon-based hybrid nanogels in the biomedical field.

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.

Bone metastasis target redox-responsive micell for the treatment of lung cancer bone metastasis and anti-bone resorption

In order to inhibit the growth of lung cancer bone metastasis and reduce the bone resorption at bone metastasis sites, a bone metastasis target micelle DOX@DBMs-ALN was prepared. The size and the zeta potential of DOX@DBNs-ALN were about 60 nm and -15 mV, respectively. DOX@DBMs-ALN exhibited high binding affinity with hydroxyapatite and released DOX in redox-responsive manner. DOX@DBMs-ALN was effectively up taken by A549 cells and delivered DOX to the nucleus of A549 cells, which resulted in strong cytotoxicity on A549 cells. The in vivo experimental results indicated that DOX@DBMs-ALN specifically delivered DOX to bone metastasis site and obviously prolonged the retention time of DOX in bone metastasis site. Moreover, DOX@DBMs-ALN not only significantly inhibited the growth of bone metastasis tumour but also obviously reduced the bone resorption at bone metastasis sites without causing marked systemic toxicity. Thus, DOX@DBMs-ALN has great potential in the treatment of lung cancer bone metastasis.