Acid–degradable carboxymethyl chitosan nanogels via an ortho ester linkage mediated improved penetration and growth inhibition of 3-D tumor spheroids in vitro

A photocrosslinked methacrylated carboxymethyl chitosan/oxidized locust bean gum double network hydrogel for cartilage repair

Repairing articular cartilage defects is a great challenge due to the poor self-regenerative capability of cartilage. Inspired by active substances found in the natural cartilage extracellular matrix, we used methacrylated carboxymethyl chitosan (MA-CMCS) and oxidized locust bean gum (OLBG) as the hydrogel backbone, and prepared a photocrosslinked dual network hydrogel containing allicin and decellularized cartilage powder (DCP). The rheological, swelling and water retention capacities of MA-CMCS@OLBG-Allicin/DCP (MCOAC) hydrogels were investigated to confirm the successful preparation of hydrogels suitable for cartilage repair. The MCOAC hydrogels showed good antibacterial ability to kill S. aureus and E. coli and anti-inflammatory properties due to the introduction of allicin. Furthermore, MA-CMCS@OLBG-Allicin/DCP hydrogels presented good cytocompatibility due to the addition of DCP, which could promote chondrocyte proliferation and promote the differentiation of BMSCs to chondrocytes. Further studies in vivo demonstrated that the DCP-contained MCOAC hydrogel exhibited superior performance in promoting cartilage tissue growth and wound healing in articular cartilage defects. Thus, the MCOAC hydrogel is a promising cartilage repair hydrogel with potential for clinical use.

An update review of smart nanotherapeutics and liver cancer: opportunities and challenges

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer, typically diagnosed in advanced stages. Chemotherapy is necessary for treating advanced liver cancer; however, several challenges affect its effectiveness. These challenges include low specificity, high dosage requirements, high systemic toxicity and severe side effects, which significantly limit the efficacy of chemotherapy. These limitations can hinder the treatment of HCC. This review focuses on the prevalence of HCC, different types of liver cancer and the staging of the disease, along with available treatment methods. Additionally, explores recent and relevant studies on smart drug- and gene-delivery systems specifically designed for HCC. These systems include targeted endogenous and exogenous stimuli-responsive platforms.

A multi-crosslinking strategy of organic and inorganic compound bio-adhesive polysaccharide-based hydrogel for wound hemostasis

Polysaccharides are naturally occurring polymers with exceptional biodegradable and biocompatible qualities that are used as hemostatic agents. In this study, photoinduced CC bond network and dynamic bond network binding was used to give polysaccharide-based hydrogels the requisite mechanical strength and tissue adhesion. The designed hydrogel was composed of modified carboxymethyl chitosan (CMCS-MA) and oxidized dextran (OD), and introduced hydrogen bond network through tannic acid (TA) doping. Halloysite nanotubes (HNTs) were also added, and the effects of various doping amount on the performance of the hydrogel were examined, in order to enhance the hemostatic property of hydrogel. Experiments on vitro degradation and swelling demonstrated the strong structural stability of hydrogels. The hydrogel has improved tissue adhesion strength, with a maximum adhesion strength of 157.9 kPa, and demonstrated improved compressive strength, with a maximum compressive strength of 80.9 kPa. Meanwhile, the hydrogel had a low hemolysis rate and had no inhibition on cell proliferation. The created hydrogel exhibited a significant aggregation effect on platelets and a reduced blood clotting index (BCI). Importantly, the hydrogel can quickly adhere to seal the wound and has good hemostatic effect in vivo. Our work successfully prepared a polysaccharide-based bio-adhesive hydrogel dressing with stable structure, appropriate mechanical strength, and good hemostatic properties.

Lyophilized Platelet-Rich Fibrin Exudate-Loaded Carboxymethyl Chitosan/GelMA Hydrogel for Efficient Bone Defect Repair

Platelet-rich fibrin (PRF) is an autologous growth factor carrier that promotes bone tissue regeneration, but its effectiveness is restrained by poor storage capabilities, uncontrollable concentration of growth factors, unstable shape, etc. Herein, we developed a photocrosslinkable composite hydrogel by incorporating lyophilized PRF exudate (LPRFe) into the carboxymethyl chitosan methacryloyl (CMCSMA)/gelatin methacryloyl (GelMA) hydrogel to effectively solve the dilemma of PRF. The hydrogel possessed suitable physical properties and sustainable release ability of growth factors in LPRFe. The LPRFe-loaded hydrogel could improve the adhesion, proliferation, migration, and osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs). Furthermore, the animal experiments demonstrated that the hydrogel possessed excellent biocompatibility and biodegradability, and the introduction of LPRFe in the hydrogel can effectively accelerate the bone healing process. Conclusively, the combination of LPRFe with CMCSMA/GelMA hydrogel may be a promising therapeutic approach for bone defects.

Tumor Microenvironment-Based Stimuli-Responsive Nanoparticles for Controlled Release of Drugs in Cancer Therapy

With the development of nanomedicine technology, stimuli-responsive nanocarriers play an increasingly important role in antitumor therapy. Compared with the normal physiological environment, the tumor microenvironment (TME) possesses several unique properties, including acidity, high glutathione (GSH) concentration, hypoxia, over-expressed enzymes and excessive reactive oxygen species (ROS), which are closely related to the occurrence and development of tumors. However, on the other hand, these properties could also be harnessed for smart drug delivery systems to release drugs specifically in tumor tissues. Stimuli-responsive nanoparticles (srNPs) can maintain stability at physiological conditions, while they could be triggered rapidly to release drugs by specific stimuli to prolong blood circulation and enhance cancer cellular uptake, thus achieving excellent therapeutic performance and improved biosafety. This review focuses on the design of srNPs based on several stimuli in the TME for the delivery of antitumor drugs. In addition, the challenges and prospects for the development of srNPs are discussed, which can possibly inspire researchers to develop srNPs for clinical applications in the future.

Facile synthesis of chitosan-based nanogels through photo-crosslinking for doxorubicin delivery

Chitosan-based nanogels are effective carriers for drug delivery due to their biocompatibility and biodegradability. However, the chemically cross-linked nanogels usually require complicated procedures or tough conditions. Herein, we report a simple approach to generate chitosan-based nanogels by photo-crosslinking of poor solvent-induced nanoaggregates without requiring any emulsifying agent, catalyst, or external crosslinker. O-nitrobenzyl alcohol-modified carboxymethyl chitosan was synthesized and self-crosslinked into the nanogels in a mixed solution of ethanol and water under 365 nm light irradiation due to UV-induced primary amine and o-nitrobenzyl alcohol cyclization. The nanogels (CMC-NBA NPs) and lactobionic acid-decorated nanogels (LACMC-NBA NPs) displayed a uniform diameter (~200 nm) and excellent stability under physiological conditions. Notably, the nanogels exhibited a high loading content (~28 %) due to π-π stacking and electrostatic interactions between doxorubicin (DOX) and the carriers. These DOX-loaded nanogels showed rapid drug release under slightly acidic conditions. The cell and animal experiments confirmed that LACMC-NBA NPs increased cellular uptake, improved cytotoxicity in tumor cells, and enhanced growth inhibition in vivo than CMC-NBA NPs. Thus, these photo-crosslinked nanogels possess great potential for DOX delivery.

Recent Progress in Bio-Responsive Drug Delivery Systems for Tumor Therapy

Spatially- and/or temporally-controlled drug release has always been the pursuit of drug delivery systems (DDSs) to achieve the ideal therapeutic effect. The abnormal pathophysiological characteristics of the tumor microenvironment, including acidosis, overexpression of special enzymes, hypoxia, and high levels of ROS, GSH, and ATP, offer the possibility for the design of stimulus-responsive DDSs for controlled drug release to realize more efficient drug delivery and anti-tumor activity. With the help of these stimulus signals, responsive DDSs can realize controlled drug release more precisely within the local tumor site and decrease the injected dose and systemic toxicity. This review first describes the major pathophysiological characteristics of the tumor microenvironment, and highlights the recent cutting-edge advances in DDSs responding to the tumor pathophysiological environment for cancer therapy. Finally, the challenges and future directions of bio-responsive DDSs are discussed.

Application of Chitosan and Its Derivative Polymers in Clinical Medicine and Agriculture

Chitosan is a biodegradable natural polymer derived from the exoskeleton of crustaceans. Because of its biocompatibility and non-biotoxicity, chitosan is widely used in the fields of medicine and agriculture. With the latest technology and technological progress, different active functional groups can be connected by modification, surface modification, or other configurations with various physical, chemical, and biological properties. These changes can significantly expand the application range and efficacy of chitosan polymers. This paper reviews the different uses of chitosan, such as catheter bridging to repair nerve broken ends, making wound auxiliaries, as tissue engineering repair materials for bone or cartilage, or as carriers for a variety of drugs to expand the volume or slow-release and even show potential in the fight against COVID-19. In addition, it is also discussed that chitosan in agriculture can improve the growth of crops and can be used as an antioxidant coating because its natural antibacterial properties are used alone or in conjunction with a variety of endophytic bacteria and metal ions. Generally speaking, chitosan is a kind of polymer material with excellent development prospects in medicine and agriculture.

Angiopep-2-Modified Carboxymethyl Chitosan-Based pH/Reduction Dual-Stimuli-Responsive Nanogels for Enhanced Targeting Glioblastoma

Glioblastoma (GBM) is a fatal brain tumor with poor prognosis. Blood-brain barrier (BBB) prevents the effective delivery of chemotherapeutic agents to GBM. Herein, we developed a pH/reduction-sensitive carboxymethyl chitosan nanogel (CMCSN) modified by targeting peptide angiopep-2 (ANG) and loaded with doxorubicin (DOX). The multifunctional nanogel (DOX-ANG-CMCSN) exhibited good pH and reduction sensitivity, ideal stability, and biocompatibility. Its hydrodynamic diameter was 190 nm, drug loading was 12.7%, and the cumulative release rate of 24 h was 82.3% under the simulated tumor microenvironment. More importantly, the modification of ANG significantly enhanced BBB penetration and tumor targeting ability both in vivo and in vitro. DOX-ANG-CMCSN achieved 2-3-fold higher uptake and an enhanced antitumor activity compared with nontargeted DOX-CMCSN. Therefore, the targeted nanogels with the pH/reduction dual-stimuli response may provide a promising platform for GBM-targeted chemotherapy.

Hybrid nanoparticles based on ortho ester-modified pluronic L61 and chitosan for efficient doxorubicin delivery

Tumor intrinsic or acquired multidrug resistance (MDR) is still one of the major obstacles to the success of nanomedicine. To address this, the pH-sensitive nanoparticles (L61-OE-CS) with MDR-reversal ability were prepared by the crosslinking between acid-labile ortho-ester-modified pluronic (L61-OE) and chitosan (CS) for efficient doxorubicin (DOX) delivery. The size and micromorphology of the prepared nanoparticles were observed by dynamic light scanning and scanning electron microscopy and the nanoparticles displayed a uniform spherical shape with a diameter around 200 nm. The pH-triggered morphology change of the nanoparticles was also observed by scanning electron microscope. Drug release profiles under different pH values showed that DOX release amount within 72 h reached 16% (pH 7.4) and 76.5% (pH 5.0), respectively. In vitro cellular uptake and MTT assay demonstrated that the ortho ester and pluronic-based nanoparticles had higher cytotoxicity than non-sensitive nanoparticles. In vivo antitumor experiments also proved the superiority of the dual-functional nanoparticles, and the tumor growth inhibition rate (TGI) on day 14 was higher than 80%. Therefore, L61-OE-CS nanoparticles have great potential to be used as drug carriers in anticancer therapy.

Synthesis of pH-sensitive hyaluronic acid nanogels loaded with paclitaxel and interferon gamma: Characterization and effect on the A549 lung carcinoma cell line

Lung cancer is one of the deadliest cancers in various populations. Apart from the effects that anticancer drugs such as paclitaxel (PTX) have on cancer cells, they also have many side effects on healthy cells. Interferon gamma (IFN-γ) is also one of the cytokines used in the treatment of cancer. Current research is focused on providing new drug carriers to find new therapeutic goals. After synthesis of nanogels and loading of PTX and IFN-γ, the cytotoxicity of these nanogels on A549 and HEK293 healthy cell line was measured by MTT assay and flow cytometry analysis. Finally, the expression of STAT1 gene was investigated using Real time-PCR. The results of MTT assay showed that the survival rate of healthy cells treated with PTX and IFN-γ-loaded nanogels was 2.15 and 2.39 times higher than cancer cells, respectively. The results also showed that the gene expression STAT1 in A549 cells exposed to these nanogels was higher than healthy cells (p < 0.05). Based on flow cytometry results, the death rate of healthy cells treated with the mentioned nanogels was lower than cancer cells (p < 0.05). Therefore, Studies showed that synthesized nanogels have positive effects on cancer cells and also have fewer side effects on healthy cells.

Lactobionic acid-modified thymine-chitosan nanoparticles as potential carriers for methotrexate delivery

In order to achieve efficient delivery of methotrexate (MTX), thymine-chitosan nanoparticles (Thy-Cs NPs) were prepared, and further decorated with lactobionic acid (LA) to obtain tumor-targeting nanoparticles (LA-Thy-Cs NPs). These nanoparticles possessed a regular spherical structure with the average size about 190-250 nm and narrow size distribution, which were kinetically stable in the physiological environment. Due to electrostatic interactions and multiple hydrogen-bonding interactions between MTX and carriers, MTX was loaded into Thy-Cs NPs with high drug loading content (~20%). MTX release from Thy-Cs NPs was significantly accelerated in the mildly acidic environment due to the destruction of two types of non-covalent interactions. In vitro cell experiments demonstrated that LA-Thy-Cs NPs could be efficiently internalized into hepatoma carcinoma cells, leading to higher cytotoxicity. Moreover, MTX-loaded LA-Thy-Cs NPs performed an enhanced growth inhibition in three-dimensional multicellular tumor spheroids. Thus, the LA decorated thymine-chitosan nanocarriers can be a promising candidate for efficient delivery of MTX.

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.

Chitosan Derivatives in Macromolecular Co-assembly Nanogels with Potential for Biomedical Applications

Maleoyl-chitosan/poly(aspartic acid) nanogels were developed and characterized in order to assess its suitability for biomedical applications. Thus, the physicochemical properties were investigated and correlated with the composition of the new structures. Dynamic light scattering measurements, correlated with transmission electron microscopy images, demonstrated that nanogels size distribution was narrow with average diameter between 186 and 246 nm, and presented positive zeta potential values. The sensitivity of nanogels at pH and temperature was also evaluated. Nanogels loaded with amoxicillin showed a controlled release profile dependent on nanogel content. The formulations loaded with amoxicillin had antibacterial properties, and the cytotoxicity tests indicated good in vivo biocompatibility. In conclusion, the new synthesized polyelectrolyte nanogels, which can provide a stable environment for the encapsulated drugs, can be used as a multifunctional platform for administration of antimicrobial agents from the spectrum of antibiotics that have a very poor biodistribution.

Nanogels for Skin Cancer Therapy via Transdermal Delivery: Current Designs

BACKGROUND

Recently, several strategies have been proposed for skin cancer therapy by transdermal delivery, and particularly the use of nanotechnology.

METHODS

This process disrupts the stratum corneum to deliver a drug through the skin, allowing it to accumulate at the tumor site.

RESULTS

Nanogels are drug delivery systems that can be applied to many diseases. Nanogel engineering has been widely studied for use in drug delivery, particularly in cancer theranostics. This review summarizes specific strategies for using nanogels to treat skin cancer, a topic that is limited in recent literature.

CONCLUSION

Advanced techniques for effective skin cancer therapy based on the nanogel's penetration and cellular uptake abilities will be discussed. Moreover, techniques for penetrating the skin, as well as drug release, permeation studies, and microscopic observations, will also be discussed.

pH- and enzyme-triggered drug release as an important process in the design of anti-tumor drug delivery systems

It is necessary to design a reasonable drug delivery system(DDS) for targeted release to overcome the potential toxicity and poor selectivity of anti-tumor drug. How a drug is released from a DDS is a critical issue that determines whether the DDS is designed successfully. We all know that the microenvironment of tumors is quite different from normal tissues, such as its acidic environment, different expression levels of some enzymes, etc. These features are widely used in the design of DDSs and play an important role in the drug release process in vivo. Numerous DDSs have been designed and synthesized. This article attention to how drugs are released from DDSs. We summarizes and classify the characteristic enzymes and chemical bonds used in the drug release process by browsing a large number of papers, and describes how they are applied in DDSs with specific examples. By understanding these acid-sensitive chemical bonds and over-expressed enzymes in tumors, different DDSs can be designed for different drug structures to solve specific problems of anti-tumor drugs.

pH-sensitive and pluronic-modified pullulan nanogels for greatly improved antitumor in vivo

It remains a crucial challenge to achieve efficient cellular uptake in tumor cells for nanoscale drug delivery systems. This work described that two multi-functional pullulan nanogels were prepared by co-polymerization between methacrylated pullulan (Pullulan-M) and different crosslink agents, an acid-labile ortho ester-modified pluronic (L61-MOE) or non-acid-sensitive methacrylated pluronic (L61-M). The prepared nanogels showed a regular spherical structure with the size about 200 nm measured by dynamic light scattering and transmission electron microscopy (TEM). Doxorubicin as a model drug was successfully encapsulated into nanogels. As expected, Pul-L61-MOE showed pH-dependent DOX release, and 25% of DOX was released at pH 7.4 while 84.48% of DOX was released at pH 5.0. In vitro cellular uptake and MTT results indicated that pH-sensitive nanogels (Pul-L61-MOE) displayed higher cellular internalization and cytotoxicity than acid-insensitive nanogels (Pul-L61-M) and free DOX. Flow cytometry assay suggested these nanogels remarkably increased intracellular reactive oxygen species (ROS) level and induced more cell apoptosis by the function of pluronic. Finally, in vivo antitumor results indicated that the multi-functional nanogels exhibit supreme antitumor efficiency, and the tumor growth inhibition (TGI) was 83.37%. Therefore, the pH-sensitive pullulan nanogels can be potential nano-carriers for drug delivery in tumor treatment.

TPGS-grafted and acid-responsive soy protein nanogels for efficient intracellular drug release, accumulation, penetration in 3D tumor spheroids of drug-resistant cancer cells

The frequent occurrence of multidrug resistance (MDR) in solid tumors is the major obstacle for nano-drug delivery systems (nDDS) to realize the successful cancer chemotherapy. Herein, we had prepared pH-responsive nanogels via cross-linking TPGS-grafted soy protein with an acid-labile ortho ester cross-linker (OEAM) to realize the efficient intracellular drugs release and accumulation, and subsequently enhance therapeutic effect in MDR tumor cells. These nanogels displayed a uniform size (~200 nm) and morphology, and the introduction of ortho ester bonds endowed nanogels stability in neutral environment and acid-degradability in acidic conditions. Cisplatin (CDDP) was successfully loaded into nanogels, which exhibited an accelerated drug release at low pH. The modification of TPGS efficiently improved cellular internalization and drug accumulation in A549/DDP cells by inhibiting the function of drug efflux pumps (MRP2 and ATP7A/7B), leading to higher cytotoxicity and apoptosis. Moreover, TPGS-grafted nanogels also showed better drug accumulation and penetration in tumor-like spheroids, and then remarkably inhibited tumor growth owing to the rapid drug release in acidic organelles. As a result, the TPGS-grafted and pH-sensitive soy protein nanogels have a great potential as a drugs carrier for the efficient cancer treatment.

Acid-breakable TPGS-functionalized and diallyl disulfide-crosslinked nanogels for enhanced inhibition of MCF-7/ADR solid tumours

Herein, the dual-functionalized nanogels were used for multidrug resistance (MDR) solid tumour therapy by combining ROS with inhibition of efflux.

Tumor microenvironment-responsive nanoparticles for cancer theragnostic applications

BACKGROUND

Cancer is one of the deadliest threats to human health. Abnormal physiochemical conditions and dysregulated biosynthetic intermediates in the tumor microenvironment (TME) play a significant role in modulating cancer cells to evade or defend conventional anti-cancer therapy such as surgery, chemotherapy and radiotherapy. One of the most important challenges in the development of anti-tumor therapy is the successful delivery of therapeutic and imaging agents specifically to solid tumors.

MAIN BODY

The recent progresses in development of TME responsive nanoparticles offers promising strategies for combating cancer by making use of the common attributes of tumor such as acidic and hypoxic microenvironments. In this review, we discussed the prominent strategies utilized in the development of tumor microenvironment-responsive nanoparticles and mode of release of therapeutic cargo.

CONCLUSION

Tumor microenvironment-responsive nanoparticles offers a universal approach for anti-cancer therapy.

TPGS-functionalized and ortho ester-crosslinked dextran nanogels for enhanced cytotoxicity on multidrug resistant tumor cells

Herein pH-sensitive nanogels (NG1) and P-glycoprotein-repressive nanogels (NG2) were prepared by copolymerization between an ortho ester crosslinker (OEAM) and tocopheryl polyethylene glycol succinate (TPGS)-free or conjugated dextran. Nanogels with or without TPGS possessed a uniform diameter (∼180 nm) and excellent stability in various physiological environments. Doxorubicin (DOX) was successfully loaded into NG1 and NG2 to give NG1/DOX and NG2/DOX, both of them showed appropriate drug release profiles under mildly acidic conditions (pH 5.0). NG2/DOX possessed higher drug enrichment and lethality than NG1/DOX did on MCF-7/ADR cells. Analysis of corresponding index of efflux activity showed that NG2 could induce depolarization of mitochondrial membrane and interfere with ATP metabolism. NG2/DOX also displayed increased penetration and growth inhibition on MCF-7/ADR multicellular spheroids. These results demonstrated that pH-sensitive TPGS-functionalized nanogels (NG2) as drug carriers had great potential to suppress drug efflux in MCF-7/ADR cells and even overcome MDR on cancer cells.