Doxorubicin-induced co-assembling nanomedicines with temperature-sensitive acidic polymer and their in-situ-forming hydrogels for intratumoral administration

Functional hydrogels for hepatocellular carcinoma: therapy, imaging, and in vitro model

Hepatocellular carcinoma (HCC) is among the most common malignancies worldwide and is characterized by high rates of morbidity and mortality, posing a serious threat to human health. Interventional embolization therapy is the main treatment against middle- and late-stage liver cancer, but its efficacy is limited by the performance of embolism, hence the new embolic materials have provided hope to the inoperable patients. Especially, hydrogel materials with high embolization strength, appropriate viscosity, reliable security and multifunctionality are widely used as embolic materials, and can improve the efficacy of interventional therapy. In this review, we have described the status of research on hydrogels and challenges in the field of HCC therapy. First, various preparation methods of hydrogels through different cross-linking methods are introduced, then the functions of hydrogels related to HCC are summarized, including different HCC therapies, various imaging techniques, in vitro 3D models, and the shortcomings and prospects of the proposed applications are discussed in relation to HCC. We hope that this review is informative for readers interested in multifunctional hydrogels and will help researchers develop more novel embolic materials for interventional therapy of HCC.

Development of Intratumoral Drug Delivery Based Strategies for Antitumor Therapy

Research for tumor treatment with significant therapy effects and minimal side-effects has been widely carried over the past few decades. Different drug forms have received a lot of attention. However, systemic biodistribution induces efficacy and safety issues. Intratumoral delivery of agents might overcome these problems because of its abundant tumor accumulation and retention, thereby reducing side effects. Delivering hydrogels, nanoparticles, microneedles, and microspheres drug carriers directly to tumors can realize not only targeted tumor therapy but also low side-effects. Furthermore, intratumoral administration has been integrated with treatment strategies such as chemotherapy, enhancing radiotherapy, immunotherapy, phototherapy, magnetic fluid hyperthermia, and multimodal therapy. Some of these strategies are ongoing clinical trials or applied clinically. However, many barriers hinder it from being an ideal and widely used option, such as decreased drug penetration impeded by collagen fibers of a tumor, drug squeezed out by high density and high pressure, mature intratumoral injection technique. In this review, we systematically discuss intratumoral delivery of different drug carriers and current development of intratumoral therapy strategies.

Highly Efficient Photodynamic Hydrogel with AIE-Active Photosensitizers toward Methicillin-Resistant Staphylococcus aureus Ultrafast Imaging and Killing

Methicillin-resistant Staphylococcus aureus (MRSA) causes great health hazards to society because most antibiotics are ineffective. Photodynamic treatment (PDT) has been proposed to combat MRSA due to the advantage of imaging-guided no-drug resistance therapy. However, the traditional photosensitizers for PDT are limited by aggregation-caused quenching for imaging and low photodynamic antibacterial efficiency. In this work, we synthesize a new aggregation-induced emission (AIE) photosensitizer (APNO), which can ultrafast distinguish between Gram-positive and Gram-negative bacteria within 3 s by AIE-active photosensitizer imaging. Meanwhile, APNO can generate antibacterial reactive oxygen species under light irradiation, which holds potential for antibacterial PDT. Then, APNO is loaded by PHEAA hydrogel to obtain a highly efficient photodynamic hydrogel (APNO@gel). In vitro results show complete inhibition of MRSA by APNO@gel under lower-power light irradiation. Transcriptome analysis is performed to investigate antibacterial mechanism of APNO@gel. Most importantly, APNO@gel also exhibits significant inhibition and killing ability of MRSA in the MRSA wound infection model, which will further promote rapid wound healing. Therefore, the photodynamic hydrogel provides a promising strategy toward MRSA ultrafast imaging and killing.

Formation of biocompatible MgO/cellulose grafted hydrogel for efficient bactericidal and controlled release of doxorubicin

In this study, MgO-doped CNC-g-PAA hydrogel was synthesized by grafting poly (acrylic acid) (PAA) onto cellulose nanocrystals (CNC) and then doped Magnesium oxide (MgO) using pH 7.0 and 12.0 to obtain an efficient nanocomposite hydrogel for antibacterial and anti-cancer activities. The synthesized nanocomposite hydrogels were evaluated by detailed characterization and confirmed the formation of a well-interconnected porous structure. MgO/CNC-g-PAA (pH = 12.0) exhibited improved bactericidal tendencies towards gram-negative and gram-positive bacteria, which was further investigated by in-silico molecular docking analyses and also examined the reactive oxygen species production by photocatalysis and free radical-scavenging assay. After this, Doxorubicin (DOX), a model anticancer drug, was successfully loaded into nanocomposites (~79 %) by electrostatic interaction and confirmed pH-triggered based release, which was over 53.7 % in 24 h. Finally, in vitro cytotoxicity-based analysis confirmed the improved antitumor efficacy of nanocomposite hydrogels. These findings revealed that MgO/CNC-g-PAA hydrogels might be prospective carriers for controlled drug delivery.

Functional Thermoresponsive Hydrogel Molecule to Material Design for Biomedical Applications

Temperature-induced, rapid changes in the viscosity and reproducible 3-D structure formation makes thermos-sensitive hydrogels an ideal delivery system to act as a cell scaffold or a drug reservoir. Moreover, the hydrogels’ minimum invasiveness, high biocompatibility, and facile elimination from the body have gathered a lot of attention from researchers. This review article attempts to present a complete picture of the exhaustive arena, including the synthesis, mechanism, and biomedical applications of thermosensitive hydrogels. A special section on intellectual property and marketed products tries to shed some light on the commercial potential of thermosensitive hydrogels.

Fabrication of injectable hydrogels from an anticancer peptide for local therapeutic delivery and synergistic photothermal-chemotherapy

The susceptibility of anticancer peptides to proteolytic degradation is often considered as a major weakness that limits systemic therapeutic applications. However, localized delivery of anticancer peptides via injectable hydrogels is expected to improve drug efficacy and reduce systemic toxicity. Herein, an injectable hydrogel with drug releasing properties, NIR responsiveness and pH sensitivity was developed from an anticancer peptide (KL), Fe³⁺ ions and protocatechualdehyde via dynamic and reversible interactions. Benefiting from the formation of Fe(III)-catechol complexes between Fe³⁺ ions and protocatechualdehyde within gel networks, the obtained hydrogel exhibited intrinsic NIR absorption properties for photothermal ablation of tumor cells, and remote light control of drug release. Besides, the pH-labile imine bonds between KL and protocatechualdehyde endowed the injectable gel with pH sensitivity for sustained release of KL under a mildly acidic environment, inducing membrane destabilization and facilitating the cell uptake of DOX for combinational chemotherapy. Both in vitro and in vivo experiments revealed that the injectable hydrogel exhibited a synergistic therapeutic effect on inhibiting tumor growth via combinational photothermal-chemotherapy. Therefore, this work provides a promising attempt to develop a therapeutic hydrogel from an anticancer peptide, which could work as a localized drug delivery platform for synergistic photothermal-chemotherapy.

Hydrogels for localized chemotherapy of liver cancer: a possible strategy for improved and safe liver cancer treatment

The systemic drug has historically been preferred for the treatment of the majority of pathological conditions, particularly liver cancer. Indeed, this mode of treatment is associated with adverse reactions, toxicity, off-target accumulation, and rapid hepatic and renal clearance. Numerous efforts have been made to design systemic therapeutic carriers to improve retention while decreasing side effects and clearance. Following systemic medication, local administration of therapeutic agents allows for higher 'effective' doses with fewer side effects, kidney accumulation, and clearance. Hydrogels are highly biocompatible and can be used for both imaging and therapy. Hydrogel-based drug delivery approach has fewer side effects than traditional chemotherapy and can deliver drugs to tumors for a longer time. The chemical and physical flexibility of hydrogels can be used to achieve disease-induced in situ accumulation as well as subsequent drug release and hydrogel-programmed degradation. Moreover, they can act as a biocompatible depot for localized chemotherapy when stimuli-responsive carriers are administrated. Herein, we summarize the design strategies of various hydrogels used for localized chemotherapy of liver cancer and their delivery routes, as well as recent research on smart hydrogels.

Intratumoral Administration of Thermosensitive Hydrogel Co-Loaded with Norcantharidin Nanoparticles and Doxorubicin for the Treatment of Hepatocellular Carcinoma

Background

The efficacy of systemic chemotherapy for hepatocellular carcinoma (HCC) is predominantly hampered by low accumulation in tumor tissue and the high systemic toxicity of anticancer drugs. In this study, we designed an in situ drug-loaded injectable thermosensitive hydrogel system for the simultaneous delivery of norcantharidin-loaded nanoparticles (NCTD-NPs) and doxorubicin (Dox) via intratumoral administration to HCC tumors.

Methods

NCTD-NPs were prepared by the thin film dispersion method using PCEC polymers as the carrier. Then, NCTD-NPs and Dox were co-encapsulated in a thermosensitive hydrogel based on Pluronic F127 (PF127) to construct a dual drug-loaded hydrogel system. The rheological properties of the drug-loaded hydrogel were studied using a rheometer. Drug release of the drug-loaded hydrogel and cytotoxicity in HepG2 cells were evaluated in vitro. An H22 tumor-bearing mice model was used to assess the in vivo antitumor activity of the drug-loaded hydrogel via intratumoral administration.

Results

The prepared drug-loaded hydrogel exhibited good thermal-sensitive properties, which remained liquid at room temperature and rapidly transformed into a non-flowing gel at body temperature, and released the drugs in a sustained manner. In vitro studies revealed that the drug-loaded hydrogel exhibited remarkable antiproliferative activity in HepG2 cells compared to free drugs. In vivo antitumor efficacy experiments showed that the drug-loaded hydrogel significantly suppressed tumor growth, alleviated side effects, and prolonged the survival time of mice bearing H22 tumors compared to the other groups. Moreover, immunohistochemical staining revealed that the expression of Ki-67 and CD31 in the drug-loaded hydrogel group was significantly lower than that in the other groups (P < 0.05), indicating that the drug-loaded hydrogel effectively inhibited tumor proliferation and angiogenesis.

Conclusion

The formulated hybrid thermosensitive hydrogel system with sustained drug release and enhanced therapeutic efficacy was demonstrated to be a promising strategy for the local-regional treatment of HCC via intratumoral administration.

Assessment of the embolization effect of temperature-sensitive p(N-isopropylacrylamide-co-butyl methylacrylate) nanogels in the rabbit renal artery by CT perfusion and confirmed by macroscopic examination

Transcatheter embolization is an important treatment method in clinical therapy, and vascular embolization material plays a key role in embolization. The temperature-sensitive p(N-isopropylacrylamide-co-butyl methylacrylate) (PIB) nanogel is a novel embolic agent. To evaluate the feasibility of the nanogel as a blood vessel embolization agent, we aimed to assess the effect of embolization with PIB nanogels in the rabbit renal artery by non-invasive computed tomography (CT) perfusion, macroscopic and histological examination. Ten healthy adult Japanese rabbits were used to implement RAE of PIB nanogels in their right kidneys. CT perfusion scans were performed pre- and post-treatment at various time-points (1, 4, 8, and 12 weeks). Two rabbits were euthanized and histologically examined at each time-point, and the remaining rabbits were euthanized at 12 weeks after embolization. The RAE efficacy of the nanogels was further confirmed by macroscopic and histological examination. The renal volume and renal blood flow (BF) of the right kidney were significantly decreased post-treatment compared with those pre-treatment (volume: pre, 9278 ± 1736 mm³; post 1 week, 5155 ± 979 mm³, P < 0.0001; post 4 weeks, 3952 ± 846 mm³, P < 0.0001; post 8 weeks, 3226 ± 556 mm³, P < 0.0001; post 12 weeks, 2064 ± 507 mm³, P < 0.0001. BF: pre, 530.81 ± 51.50 ml/min/100 ml; post 1 week, 0 ml/min/100 ml, P < 0.0001; post 4 weeks, 0 ml/min/100 ml, P < 0.0001; post 8 weeks, 0 ml/min/100 ml, P < 0.0001; post 12 weeks, 0 ml/min/100 ml, P < 0.0001). No revascularization or collateral circulation was observed on histological examination during this period, and PIB nanogels were dispersed in all levels of the renal arteries. Twelve weeks after embolization, CT perfusion showed no BF in the right renal artery and renal tissue, a finding that was consistent with histological examination showing complete embolization of the right renal artery with a lack of formation of collateral vessels. The effect of embolization on PIB was adequate, with good dispersion and permanency, and could be evaluated by non-invasive and quantitative CT perfusion.

Recent advances in thermo-sensitive hydrogels for drug delivery

Thermo-sensitive hydrogels based on different polymers have been broadly used in the pharmaceutical fields. In this review, the state-of-the-art thermo-sensitive hydrogels for drug delivery are elaborated

Injectable in Situ Forming Hydrogels of Thermosensitive Polypyrrole Nanoplatforms for Precisely Synergistic Photothermo-Chemotherapy

The combination of photothermal therapy (PTT) with chemotherapy has great potential to maximize the synergistic effect of thermo-induced chemosensitization and improve treatment performance. To achieve high drug-loading capacity as well as precise synchronization between the controllable release of chemotherapeutics and the duration of near-infrared PTT, in this work, a facile one-step method was first developed to fabricate a novel injectable in situ forming photothermal modulated hydrogel drug delivery platform (D-PPy@PNAs), in which a PNIPAM-based temperature-sensitive acidic triblock polymer [poly(acrylic acid-b-N-isopropylamide-b-acrylic acid (PNA)] was utilized as the stabilizing agent in the polymerization of polypyrrole (PPy). The in situ forming hydrogels showed a sensitive temperature-responsive sol-gel phase-transition behavior, as well as an excellent photothermal property. The strong interaction of ionic bonds together with π-π stacking interactions resulted in high doxorubicin (DOX) loading capacity and controlled/sustained drug release behavior. In addition, D-PPy@PNAs also displayed enhanced cellular uptake and promoted intratumoral penetration of DOX upon NIR laser irradiation. The synergistic photothermal therapy-chemotherapy of D-PPy@PNA hydrogels greatly improved the antitumor efficacy in vivo. Therefore, thermosensitive polypyrrole-based D-PPy@PNA hydrogels may be powerful drug delivery nanoplatforms for precisely synergistic photothermo-chemotherapy of tumors.

Thermo-sensitive hydrogels for delivering biotherapeutic molecules: A review

To date, a variety of delivery systems based on organic or inorganic materials have been investigated. Among them, hydrogels have become one of the most promising field in drug delivery system due to their unique properties. Temperature-sensitive hydrogels, which gelation at physiological temperature, gift the delivery system with excellent spatial and temporal control, and have a widely application in drug delivery, tissue engineering, imaging, and wound dressing. This review provides a brief overview on the concept and classification of temperature-sensitive hydrogels, and covers the application of temperature-sensitive gel systems in delivery of biotherapeutic molecules.

Spatiotemporally Light-Activatable Platinum Nanocomplexes for Selective and Cooperative Cancer Therapy

Highly efficient nanoarchitectures are of great interest for achieving precise chemotherapy with minimized adverse side effects in cancer therapy. However, a major challenge remains in exploring a rational approach to synthesize spatiotemporally selective vehicles for precise cancer chemotherapy. Here, we demonstrate a rational design of bifunctional light-activatable platinum nanocomplexes (PtNCs) that produce dually cooperative cancer therapy through spatiotemporally selective thermo-chemotherapy. The Pt⁴⁺-coordinated polycarboxylic nanogel is explored as the nanoreactor template, which is exploited to synthesize bifunctional PtNCs consisting of a zero-valent Pt⁰ core and a surrounding bivalent Pt²⁺ shell with tunable ratios through a facile and controllable reduction. Without light exposure, chemotherapeutic Pt²⁺ ions are tightly bound on the surface of PtNCs, efficiently reducing undesirable drug leakage and nonselective damage on normal tissues/cells. Upon light exposure, PtNCs generate much heat via photothermal conversion from the Pt⁰ core and simultaneously trigger a rapid release of chemotherapeutic Pt²⁺ ions, thereby leading to the spatiotemporally light-activatable synergistic effect of thermo-chemotherapy. Moreover, PtNCs show enhanced tumor accumulation through the heat-triggered hydrophilicity-hydrophobicity transition upon immediate light exposure after injection, dramatically facilitating in vivo tumor regression through their cooperative anticancer efficiency. This rational design of spatiotemporally activatable nanoparticles provides an insightful tool for precise cancer therapy.

pH- and photothermal-driven multistage delivery nanoplatform for overcoming cancer drug resistance

Reversing multidrug resistance (MDR) remains a big challenge in cancer therapy. Combining the hyperthermia and chemotherapy is a promising strategy for efficient cancer treatment with MDR reversal. Gold nanocages (GNCs) are an ideal photothermal (PTT)-chemotherapy integration platform due to their good photothermal conversion efficiency and the unique hollow interiors. However, insufficient tumor cell internalization and in vivo premature drug leakage restrict the anticancer activity of GNCs-based drug delivery systems. Methods: pH low insertion peptide (pHLIP)- and thermoresponsive poly(di(ethylene glycol) methyl ether methacrylate-co-oligo(ethylene glycol) methyl ether methacrylate) polymer-conjugated GNCs were rationally constructed to load anticancer drug doxorubicin (DOX@pPGNCs). Tumor acidic environment-responsive tumor cell internalization, and near-infrared (NIR) laser-induced tumor accumulation, penetration and on-demand drug release were systematically examined. Results: DOX@pPGNCs display good photothermal efficacy and thermoresponsive property. NIR laser irradiations at the tumor site significantly enhance tumor accumulation and penetration. Once DOX@pPGNCs reach the tumor site, the conformational transformation of pHLIP at the acidic tumor microenvironment contributes to the enhanced cellular internalization. Furthermore, NIR laser-triggered photothermal effects induce the shrinkage of thermoresponsive polymer, resulting in the opening of the pores of GNCs and a rapid intracellular DOX release to the nuclei. DOX@pPGNCs exhibit synergistic antitumor effect with MDR reversal in vitro and in vivo. Conclusion: DOX@pPGNCs present strong potential to overcome MDR in cancer.

The study of establishment of an in vivo tumor model by three-dimensional cells culture systems methods and evaluation of antitumor effect of biotin-conjugated pullulan acetate nanoparticles

In this study, three-dimensional (3D) hydrogels were used for human hepatocellular carcinoma (HepG2) cells culture systems in vitro and establishment of an in vivo xenografted tumor model. Based on our previous work on the biotin-conjugated pullulan acetate nanoparticles (Bio-PA NPs) as anticancer drug carriers, we further studied the anti-tumor effect of the NPs in two-dimensional (2D) and 3D cell culture system. When embedded in 3D hydrogels, HepG2 cells formed tumor spheroids and the cytoplasmic actin microfilamentrates were rearranged over a period of 7 days. In vitro cytotoxicity results indicated that HepG2 cells in 3D hydrogels were more resistant to Bio-PA NPs treatments compared to the 2D system. The tumor formation rate of in vivo xenografted tumor model using 3D culture systems method was 98.2%, which was significantly higher than that using of 2D cultured cells (76.4%). Then we injected the 3D HepG2 cells systems in the right anterior axillary of female Balb/c nude mice, and evaluate the in vivo anti-tumor efficacy of Bio-PA NPs. In summary, these results suggested that HepG2 cells in 3D hydrogel system has shown the potential to provide an in vitro and in vivo model and for the evaluation of Bio-PA NPs.

PEG-Detachable Polymeric Micelles Self-Assembled from Amphiphilic Copolymers for Tumor-Acidity-Triggered Drug Delivery and Controlled Release

The development of an intelligent biomaterial system that can efficiently accumulate at the tumor site and release a drug in a controlled way is very important for cancer chemotherapy. PEG is widely selected as a hydrophilic shell to acquire prolonged circulation time and enhanced accumulation at the tumor site, but it also restrains the cellular transport and uptake and leads to insufficient therapeutic efficacy. In this work, a PEG-detachable pH-responsive polymer that forms micelles from copolymer cholesterol grafted poly(ethylene glycol) methyl ether- D_labile-poly(β-amino ester)- D_labile-poly(ethylene glycol) methyl ether (MPEG- D_labile-PAE- g-Chol) is developed to overcome the aforementioned challenges based on pH value changes among normal physiological, extracellular (pH_e), and intracellular (pH_i) environments. PEGylated doxorubicin (DOX)-loaded polymeric micelles (DOX-PMs) can accumulate at the tumor site via an enhanced permeability and retention effect, and the PEG shell is detachable induced by cleavage of the pH_e-labile linker between the PEG segment and the main chain. Meanwhile, the pH_i-sensitive poly(β-amino ester) segment is protonated and has a high positive charge. The detachment of PEG and protonation of PAE facilitate cellular uptake of DOX-PMs by negatively charged tumor cells, along with the escape from endo-/lysosome due to the "proton-sponge" effect. The DOX molecules are controlled release from the carriers at specific pH values. The results demonstrate that DOX-PMs have the capability of showing high therapeutic efficacy and negligible cytotoxicity compared with free DOX in vitro and in vivo. Overall, we anticipate that this PEG-detachable and tumor-acidity-responsive polymeric micelle can mediate effective and biocompatible drug delivery "on demand" with clinical application potential.

Dual-targeting nanoparticles with core-crosslinked and pH/redox-bioresponsive properties for enhanced intracellular drug delivery

Multifunctional nanoparticles (NPs) with high blood-stability, tumor-targeting ability, and stimuli-bioresponsive drug release behaviors are urgently demanded. Herein, folic acid (FA) and galactose (GAL) functionalized, core-crosslinked NPs (CC NPs) with dual-targeting and pH/redox-bioresponsive properties were developed based on amphiphilic FA-poly(6-O-methacryloyl-d-galactopyranose)-b-poly[2-(diisopropylamino) ethyl methacrylate-co-pyridyl disulfide methylacrylate] [FA-PMAgGP-b-P(DPA-co-PDEMA), termed as FA-PMgDP] block copolymers, and then investigated for facilitated hepatoma-targeting delivery of doxorubicin (DOX). A series of PMgDP copolymers were synthesized though two-step RAFT copolymerization followed by acid-induced acetal deprotection reaction. Their well-defined chemical structures and compositions were characterized by ¹H NMR and gel permeation chromatography. Nano-sized, non-crosslinked PMgDP NPs (PMgDP NC NPs) with sizes of less than 25 nm in aqueous solution were self-assembled via the solvent exchange method, and PMgDP CC NPs were readily prepared in the presence of dithiothreitol. The drug-loading content of PMgDP CC NPs was up to 15.8% and its entrapment efficiency was 89.0%. In normal physiological conditions, 11.6% of DOX was released from DOX-loaded PMgDP CC NPs at 25 h, whereas in analogous intracellular microenvironment, 95.5% was released at 11 h owing to the acid-induced protonation of tertiary amine and reductive cleavage of disulfide bond in the hydrophobic core. In a cellular uptake study, FA and GAL-mediated, active, dual-targeted DOX-loaded FA-PMgDP CC NPs showed a 3.54-fold increase in cellular uptake efficiency to HepG2 cells compared to that of shown by single GAL-targeted, DOX-loaded PMgDP NC NPs. Results of in vitro cytotoxicity study showed that blank FA-PMgDP CC NPs exhibited good biocompatibility, whereas dual-targeting DOX-loaded FA-PMgDP CC NPs increased cell apoptosis. Therefore, the above results indicated that the well-constructed FA-PMgDP CC NPs with multi-synergistic effect may serve as new nanocarriers in the field of precise hepatoma-targeting drug delivery.

Rational design of temperature-sensitive blood-vessel-embolic nanogels for improving hypoxic tumor microenvironment after transcatheter arterial embolization

Transcatheter arterial embolization (TAE) plays an important role in clinical tumor therapy by accomplishing vessel-casting embolization of tumor arteries at all levels and suppressing tumor collateral circulation and vascular re-canalization. In this study, we describe smart blood-vessel-embolic nanogels for improving the anti-tumor efficacy of TAE therapy on hepatocellular carcinoma (HCC). Methods: In this study, an in vitro model composed of two microfluidic chips was used for simulating the tumor capillary network and analyzing artery-embolization properties. Also, blood-vessel-casting embolization of renal arteries was evaluated in normal rabbits. Using a VX2 tumor-bearing rabbit model, the therapeutic efficacy of TAE on HCC was investigated for tumor growth, necrosis, and proliferation. Neovascularization and collateral circulation were evaluated by immunofluorescent detection of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), and CD31 following the TAE therapy of VX2 tumor-bearing rabbits. Results: Sufficient embolization of all eight levels of micro-channels was achieved in a tumor-vessel-mimetic model with two microfluidic chips using PIBI-2240, and was further confirmed in renal arteries of normal rabbit. Effective inhibition of tumor collateral circulation and vascular re-canalization was observed in VX2 tumor-bearing rabbits due to the reduced expression levels of HIF-1α, VEGF, and CD31. Conclusions: The exceptional anti-tumor effect of PIBI-2240 observed in this study suggested that it is an excellent blood-vessel-embolic material for tumor TAE therapy.

Precise synchronization of hyperthermia-chemotherapy: photothermally induced on-demand release from injectable hydrogels of gold nanocages

Though a therapeutic sequence plays a key role in tumor therapy, little attention has been paid to its influence on multimodal combined therapy. Herein, we developed gold nanocages (GNC@PNA-hls) decorated with two kinds of temperature sensitive p(N-isopropyl-acrylamide-acrylic acid) copolymers (PNA-hs and PNA-ls) for precise antitumor coordination of thermo-chemotherapy. Doxorubicin-loaded GNC@PNA-hls (Dox-GNC@PNA-hls) showed a steady photothermally induced on-demand release under multiple near-infrared (NIR) irradiations. In vitro evaluations indicated that concurrent thermo-chemotherapy treatments (Dox - L) showed the best antitumor effect, compared with the sequence of either doxorubicin treatment followed by NIR radiation (Dox + L) or NIR radiation followed by doxorubicin treatment (L + Dox). The in vivo antitumor efficacy also indicated that the tumor volume was totally suppressed (ca. 0.14 cm3) by the treatment of Dox-GNC@PNA-hls with NIR radiation for 14 days. These results indicated that Dox-GNC@PNA-hls could achieve precise synchronization between hyperthermia and chemotherapy, and effectively enhance their antitumor efficacy.

Injectable hydrogel encapsulating Cu2MnS2 nanoplates for photothermal therapy against breast cancer

BACKGROUND

In order to explore the possibility of treating breast cancer by local photo-therapy, a photothermal agents loaded in situ hydrogel was established. In detail, The Cu2MnS2 nanoplates were prepared by one-pot synthesis and, the thermosensitive Pluronic F127 was used as the hydrogel matrix. The Cu2MnS2 nanoplates and the hydrogel were characterized by morphous, particle size, serum stability, photothermal performance upon repeated 808 nm laser irradiation as well as the rheology features. The therapeutic effects of the Cu2MnS2 nanoplates and the hydrogel were evaluated qualitatively and quantitatively in 4T1 mouse breast cancer cells. The retention, photothermal efficacy, therapeutic effects and systemic toxicity of the hydrogel were assessed in tumor bearing mouse model.

RESULTS

The Cu2MnS2 nanoplates with a diameter of about 35 nm exhibited satisfying serum stability, photo-heat conversion ability and repeated laser exposure stability. The hydrogel encapsulation did not negatively influence the above features of the photothermal agent. The nanoplates loaded in situ hydrogel shows a phase transition at body temperature and, as a result, a long retention in vivo.

CONCLUSIONS

The photothermal agent embedded hydrogel played a promising photothermal therapeutic effects in tumor bearing mouse model with low systemic toxicity after peritumoral administration.

Theranostic niosomes for direct intratumoral injection: marked enhancement in tumor retention and anticancer efficacy

AIM

For simultaneous bioimaging and drug delivery via direct intratumoral injection, doxorubicin and Ag₂S quantum dots co-loaded multifunctional niosomes were prepared and fully characterized.

MATERIALS & METHODS

Various theranostic niosomes were prepared and investigated regarding cytotoxicity, in vivo imaging, drug accumulation in breast cancer tumor and antitumor activity.

RESULTS

Niosomes composed of Tween-60, Tween-80 or Span 60 produced strong and more durable detectable fluorescence signals. Despite a higher accumulation of Tween-60 niosomes in tumor, the Span 60 formulation showed the highest antitumor efficacy when compared with the free drug (71.7 and 20.3% inhibition in tumor growth, respectively).

CONCLUSION

Direct intratumoral injection of theranostic niosomes with appropriate composition could be a powerful tool for combined multimodal imaging and therapy.

Injectable Hexapeptide Hydrogel for Localized Chemotherapy Prevents Breast Cancer Recurrence

Although postsurgical chemotherapy is frequently used for the treatment of breast cancer, tumor recurrence is still a frequent event. Enhancing the efficacy of chemotherapy via localized drug delivery may help to prevent breast cancer recurrence. To achieve this goal, we designed a hydrogel nanocarrier that could be injected at the tumor site by coassembly of tailor-made hexapeptide and doxorubicin. Evidently, on the basis of our findings, the sustained release of drug from the hydrogel led to a reduction in cancer recurrence, including the suppression of primary regrowth and distant metastasis. This localized chemotherapy strategy did not show any obvious side effects in vivo and represents a promising adjuvant therapeutic strategy for breast cancer recurrence.

Fabrication of inherently radiopaque BaSO4@BaAlg microspheres by a one-step electrospraying method for embolization

Inherently radiopaque BaSO₄@BaAlg microspheres were fabricated by a one-step electrospraying method for embolization and noninvasive examination after operations.

Temperature-sensitive poly(phenyleneethynylene) nanomedicines for intracellular tracking via fluorescence resonance energy transfer

pNIPAM-grafted poly(phenyleneethynylene) nanoparticles (pNE NPs) were synthesized by atom transfer radical polymerization and Sonogashira coupling reaction and were developed as novel self-indicating drug nano-carriers for monitoring the intracellular drug release.

Temperature/pH-Sensitive Nanoantibiotics and Their Sequential Assembly for Optimal Collaborations between Antibacterial and Immunoregulation

Treatment of bacterial infections due to the fast emergence of drug-resistant bacteria is a significant challenge faced in modern medicine. Here the authors report a drug-induced self-assembly nanoantibiotic for treating bacterial infection, with temperature/pH-sensitivity, synergistic antibacterial effect of silver and antibiotics, and immunoregulatory effect. In this nanoantibiotic, smart polymer p(N-isopropylacrylamide-b-acrylic acid) triblock polymer (PNA) utilized to encapsulate the drugs provides convenience in preparing this structure simply through drug-induced self-assembly and controllable release profile by changing the sequence of addition of different drugs. The polymer also allows the nanoantibiotic to be responsive to multiple external stimuli such as pH, temperature, and ionic strength. The silver and antibiotics codelivered in this nanoantibiotic can exert a synergistic antibacterial effect due to the different antibacterial mechanisms. More importantly, macrophages can be activated into an M2 phenotype to promote tissue repair by this nanoantibiotic for the negative surface charge and the antibiotics contained. The self-assembly nanoantibiotic exhibited great promise to be applied in the treatment of bacterial infection and provide favorable utility for inflammation treatment, tissue engineering, and targeted therapy.

pH-responsive self-healing injectable hydrogel based on N-carboxyethyl chitosan for hepatocellular carcinoma therapy

Injectable hydrogels with pH-responsiveness and self-healing ability have great potential for anti-cancer drug delivery. Herein, we developed a series of polysaccharide-based self-healing hydrogels with pH-sensitivity as drug delivery vehicles for hepatocellular carcinoma therapy. The hydrogels were prepared by using N-carboxyethyl chitosan (CEC) synthesized via Michael reaction in aqueous solution and dibenzaldehyde-terminated poly(ethylene glycol) (PEGDA). Doxorubicin (Dox), as a model of water-soluble small molecule anti-cancer drug was encapsulated into the hydrogel in situ. Self-healing behavior of the hydrogels was investigated at microscopic and macroscopic levels, and the hydrogels showed rapid self-healing performance without any external stimulus owing to the dynamic covalent Schiff-base linkage between amine groups from CEC and benzaldehyde groups from PEGDA. The chemical structures, rheological property, in vitro gel degradation, morphology, gelation time and in vitro Dox release behavior from the hydrogels were characterized. Injectability was verified by in vitro injection and in vivo subcutaneous injection in a rat. pH-responsive behavior was verified by in vitro Dox release from hydrogels in PBS solutions with different pH values. Furthermore, the activity of Dox released from hydrogel matrix was evaluated by employing human hepatocellular liver carcinoma (HepG2). Cytotoxicity test of the hydrogels using L929 cells confirmed their good cytocompatibility. Together, these pH-responsive self-healing injectable hydrogels are excellent candidates as drug delivery vehicles for liver cancer treatment. STATEMENT OF SIGNIFICANCE: pH-responsive drug delivery system could release drug efficiently in targeted acid environment and minimalize the amount of drug release in normal physiological environment. pH-sensitive injectable hydrogels as smart anti-cancer drug delivery carriers show great potential application for cancer therapy. The hydrogels with self-healing property could prolong their lifetime during implantation and provide the advantage of minimally invasive surgery and high drug-loading ratio. This work reported the design of a series of pH-responsive self-healing injectable hydrogels based on N-carboxyethyl chitosan synthesized in aqueous solution and dibenzaldehyde-terminated poly(ethylene glycol) via a green approach, and demonstrated their potential as intelligent delivery vehicle of doxorubicin for hepatocellular carcinoma therapy via the pH-responsive nature of dynamic Schiff base.

Engineered Hydrogels in Cancer Therapy and Diagnosis

Over the last decade, numerous investigations have attempted to clarify the intricacies of tumor development to propose effective approaches for cancer treatment. Thanks to the unique properties of hydrogels, researchers have made significant progress in tumor model reconstruction, tumor diagnosis, and associated therapies. Notably, hydrogel-based systems can be adjusted to respond to cancer-specific hallmarks and/or external stimuli. These well-known drug reservoirs can be used as smart carriers for multiple cargos, including both naked and nanoparticle-encapsulated chemotherapeutics, genes, and radioisotopes. Recent works have attempted to specialize hydrogels for cancer research; we comprehensively review this topic for the first time, synthesizing past results and defining paths for future work.

Cisplatin-directed coordination-crosslinking nanogels with thermo/pH-sensitive triblock polymers: improvement on chemotherapic efficacy via sustained release and drug retention

To realize the sustained release and long-term intratumoural retention of water-soluble cisplatin, thermo/pH-sensitive cisplatin-directed coordination-crosslinking nanogels (Pt-PNA) were developed via the coordination bonds of Pt-carboxyl groups. As the coordination ratio (CR) of the Pt-carboxyl bonds increased from 5% to 35%, the sizes of the Pt-PNA nanogels decreased from 999 nm to 167 nm, and their zeta potentials increased from -35 mV to -13 mV. Only through a simple mixing of cisplatin and PNAs, the entrapment efficiencies (EEs) of the Pt-PNA nanogels reached near 100% (>90%), and the drug-loading amounts (DLs) of cisplatin could achieve up to 25.5 ± 0.1%. For water-soluble cisplatin, Pt-PNA nanogels exhibited a sustained release for as long as 5 days. The thermo/pH-sensitive sol-gel phase-transition behaviour of the Pt-PNA nanogels were investigated via inverting-vial and rheological methods. Platinum elemental analysis indicated that the Pt-PNA nanogels showed a much stronger ability of cisplatin retention in tumours than free cisplatin. The platinum content in a tumour treated by the Pt-PNA nanogels was far higher than that by free cisplatin: 200.7 ± 63.6 μg vs. 82.7 ± 26.8 μg at the 1st day, or 118.9 ± 35.2 μg vs. 18.5 ± 9.4 μg at the 14th day. The evaluation of the in vivo antitumour efficacy indicated that only after a single dose of Pt-PNA nanogels, the tumour volume continuously decreased to 0.73 ± 0.07 times that of the original tumour volume (OTV) for 14 days; however, it rapidly increased by 3.37 ± 0.82, 8.01 ± 0.53 and 9.25 ± 1.85 times that of the OTV with the same dose of free cisplatin, PNA, and NS, respectively. Some preliminary evaluations of the biocompatibility indicated that the toxic side effects of cisplatin could be greatly improved via cisplatin-directed coordination-crosslinking with PNA. As a result, Pt-PNA nanogels could likely become a promising versatile strategy for improving antitumour efficacy and reducing the toxicity and size effects of platinum-based drugs, and they could also be developed as promising nanomedicines for regional chemotherapy.