Self-Assembled Degradable Nanogels Provide Foliar Affinity and Pinning for Pesticide Delivery by Flexibility and Adhesiveness Adjustment

At present, it is highly important to develop a simple and compatible nano delivery system for pesticides for foliar application, which can improve their insecticidal efficacy and resistance to adverse climates while reducing the environmental risks. Polyethylene glycol and 4,4-methylenediphenyl diisocyanate are used as hydrophilic soft and hydrophobic hard segments, respectively, for polymer self-assembly and polyurethane gelation in a nanoreactor. The nanocarrier synthesis and the pesticide loading are realized by a one-step integration procedure and suited well for hydrophobic active compounds. Modifying the molecular structure of the soft segment can adjust the flexibility of the nanocarriers and result in viscosity and deformation characteristics. After foliar spray application, the foliar flattening state of the nanogels increases the foliar protection area by 2.21 times and improves both pesticide exposure area and target contact efficiency. Concurrently, the flexibility and viscosity of the nanogels increase the washing resistance and the retention rate of the pesticide by approximately 80 times under continuous washing. The encapsulation of the nanogels reduces the foliar ultraviolet (UV) degradation and aquatic pesticide exposure, which increase the security of λ-cyhalothrine by 9.33 times. Moreover, the degradability of nanogels is beneficial for pesticide exposure and reducing pollution. This system has simple preparation, good properties, and environmental friendliness, making the nanocarriers promising for delivering pesticides.

Hollow Mesoporous Silica Nanoparticles Gated by Chitosan-Copper Sulfide Composites as Theranostic Agents for the Treatment of Breast Cancer

The combination of chemotherapy and photothermal therapy (PTT) into a single formulation has attracted increasing attention as a strategy for enhancing cancer treatment. Here, hollow mesoporous silica nanoparticles (HMSNs) were used as a base carrier material, loaded with the anti-cancer drug doxorubicin (DOX), and surface functionalized with chitosan (CS) and copper sulfide (CuS) nanodots to give HMSNs-CS-DOX@CuS. In this formulation, the CuS dots act as gatekeepers to seal the surface pores of the HMSNs, preventing a burst release of DOX into the systemic circulation. S-S bonds connect the CuS dots to the HMSNs; these are selectively cleaved under the reducing microenvironment of the tumor, permitting targeted drug release. This, coupled with the PTT properties of CuS, results in a potent chemo/PTT platform. The HMSNs-CS-DOX@CuS nanoparticles have a uniform size (150 ± 13 nm), potent photothermal properties (η = 36.4 %), and tumor-targeted and near infrared (NIR) laser irradiation-triggered DOX release. In vitro and in vivo experimental results confirmed that the material has good biocompatibility, but is effectively taken up by cancer cells. Moreover, the CuS nanodots permit simultaneous thermal/photoacoustic dual-modality imaging. Treatment with HMSNs-CS-DOX@CuS and NIR irradiation caused extensive apoptosis in cancer cells both in vitro and in vivo, and could dramatically extend the lifetimes of animals in a murine breast cancer model. The system developed in this work therefore merits further investigation as a potential nanotheranostic platform for cancer treatment. STATEMENT OF SIGNIFICANCE: Conventional cancer chemotherapy is accompanied by unavoidable off-target toxicity. Combination therapies, which can ameliorate these issues, are attracting significant attention. Here, the anticancer drug doxorubicin (DOX) was encapsulated in the central cavity of chitosan (CS)-modified hollow mesoporous silica nanoparticles (HMSNs). The prepared system can target drug release to the tumor microenvironment. When exposed to near infrared laser (NIR) irradiation, CuS nanodots located at the surface pores of the HMSNs generate energy, accelerating drug release. In addition, a systematic in vitro and in vivo evaluation confirmed the HMSNs-CS-DOX@CuS platform to give highly effective synergistic chemotherapeutic-photothermal therapy and have effective thermal/photoacoustic dual-imaging properties. This work may open up a new avenue for NIR-enhanced synergistic therapy with simultaneous thermal/photoacoustic dual imaging.

Anti-P0 Antibody-Conjugated Nanoscale Contrast Agent Targeting the Myelin Sheath for Intraoperative Visible Delineation of Cranial Nerves

The preservation of cranial nerves is a major problem that surgeons encounter when resecting a tumor in the posterior cranial fossa. Most cranial nerve injuries occur because the tight adhesion between the tumor capsule and cranial nerves renders the nerves indistinguishable. In this study, a nerve-specific nanoscale contrast agent was developed for visually distinguishing cranial nerves from the tumor surface in real time. To enable the contrast agent to specifically bind peripheral nerves, a previously reported biodegradable multiblock polyurethane nanoparticle (BMPU NP) was conjugated with an antibody against myelin protein zero (MPZ, P0), which is expressed on myelin sheaths in peripheral nerve fibers. Coomassie brilliant blue G (CB) was encapsulated into the BMPU NP for visual contrast. The CB-BMPU NP specifically stained mouse peripheral nerve fibers blue when directly applied to the nerve surface ex vivo and in vivo. The CB-BMPU NP also achieved satisfactory visual contrast of the trigeminal nerve in a mouse nerve-tissue adhesion model. This study offers new insights for the development of intraoperatively applied nerve-specific contrast agents for delineating cranial nerves adhered to tumors.

Poly(ethylene glycol)-sheddable reduction-sensitive polyurethane micelles for triggered intracellular drug delivery for osteosarcoma treatment

BACKGROUND

The survival rate of osteosarcoma therapy still lags behind overall cancer therapies due to the intrinsic or acquired drug resistance. Developing novel drug delivery systems that may overcome drug resistance would greatly facilitate osteosarcoma therapy.

METHODS

Poly(ethylene glycol) (PEG)-sheddable reduction-sensitive polyurethane (SS-PU-SS-PEG) was synthesized using a disulfide-containing polycaprolactone diol as the hydrophobic block and a cystamine-functionalized PEG as the hydrophilic block. SS-PU-SS-PEG micelles were then prepared to load the anti-tumor drug Doxorubicin (DOX) in order to achieve triggered intracellular drug delivery to improve the efficacy of osteosarcoma therapy.

RESULTS

When DOX was used as a model drug, the drug-loaded SS-PU-SS-PEG micelles were about 82∼94 nm in diameter and exhibited good stability in phosphate buffer saline (PBS). The micelles could release about 80% DOX in a quantitative fashion within 5 hours under a reductive environment. The intracellular drug release of DOX-loaded SS-PU-SS-PEG micelles increased upon incubation with Saos-2 cells in vitro. The micelles had good biocompatibility. In vitro, DOX-loaded SS-PU-SS-PEG micelles showed significant antitumor activity toward Saos-2 cells, which was close to that of free DOX. In vivo, DOX-loaded SS-PU-SS-PEG micelles exhibited better antitumor activity than free DOX.

CONCLUSION

Findings from this study suggest that the SS-PU-SS-PEG micelles could achieve well-controlled triggered drug release in a reduction environment and could therefore improve the antitumor efficacy of osteosarcoma therapies.

TRANSLATION POTENTIAL OF THIS ARTICLE

In this study we developed PEG-sheddable reduction-sensitive polyurethane micelles (SS-PU-SS-PEG), which were able to achieve well-controlled triggered release of anti-tumor drug Doxorubicin (DOX) in an intracellular reduction environment. DOX-loaded SS-PU-SS-PEG micelles markedly improved the antitumor efficacy in a Saos-2 cells-bearing xenograft tumor model. Therefore, such micelles might be used as a novel drug delivery system for osteosarcoma treatment.

pH and reduction dual-responsive micelles based on novel polyurethanes with detachable poly(2-ethyl-2-oxazoline) shell for controlled release of doxorubicin

We describe a biodegradable amphiphilic polyurethane (PU) with disulfide bonds in the main chain [PEtOz-b-PU(SS)-b-PEtOz]. This multi-block PU was synthesized using poly (ε-caprolactone) diol (PCL-SS-PCL) and poly (2-ethyl-2-oxazoline) (PEtOz-OH) as soft segments, and bis (2-isocyanatoethyl) disulfide as the hard segment. Acid-sensitive PEtOz-OH was used as a hydrophilic segment for pH sensitivity. And reduction sensitivity was induced via disulfide bonds incorporated into the hydrophobic poly (ε-caprolactone) segment of the amphiphilic PUs. The system can self-assemble to form micelles responsive to pH and reducing conditions. The properties of the micelle were studied with dynamic light scattering and scanning electron microscopy. Doxorubicin (DOX) was chosen as a model drug. The in vitro release studies showed that PEtOz-b-PU(SS)-b-PEtOz micelle could degrade more rapidly and completely in a reductive and acidic environment [10 mM dl-Dithiothreitol, pH 5.0]. The methyl tetrazolium (MTT) assay and fluorescent microscopy confirmed the cytotoxicity of the DOX-loaded micelles. This work provides a promising dual-responsive drug carrier based on amphiphilic PU to achieve efficient drug delivery.

Facile preparation of biodegradable dual stimuli-responsive micelles from waterborne polyurethane for efficient intracellular drug delivery

A novel waterborne polyurethane based on main chain degradation under acidic and reductive conditions of tumors was synthesized.

Polymer coated mesoporous ceramic for drug delivery in bone tissue engineering

Treatment strategy for various bone fracture and defects the researchers are focusing to develop a new carrier for delivering the drug into injured area with controlled and sustained manner using biomaterials with dynamic architecture orientation. Ceramic materials are resembled with bone compositional architecture and better bioactivity, degradability as well as antimicrobial activity made its enormous application in bone tissue engineering (BTE). Current focus in regenerative medicine were orchestration of biomaterials with the capacity of loading the drugs, growth factors, ionic components to promote better healing of bone tissue. Mesoporous type materials owed a great look towards the delivery of drugs, growth factors, etc in BTE because of its unique geometry. So the guest molecules loaded with geometrically organized ceramics would deliver onto the site of injury in controlled manner also the guiding and regulation of delivery of molecules have been controlled with the polymers response to different stimulation or biochemical factors as either scaffold or encapsulated particles for bone regeneration. Hence the review aims to describing the recent progress in bone tissue engineering using the ceramic based mesoporous materials encapsulated with polymers respond to different physiochemical stimulation for the efficient and controlled delivery of drug/growth factors for better bone healing.

Precise ratiometric loading of PTX and DOX based on redox-sensitive mixed micelles for cancer therapy

PTX and DOX have different anticancer mechanisms. The combination of the two anticancer drugs could synergically enhance their anticancer effect, but simultaneously accompanied by severe side effects. In the present study, we constructed a mixed micelle system based on redox-sensitive mPEG-SS-PTX and mPEG-SS-DOX conjugate. The drug delivery system has a fixed and high drug loading content of 24.2% (PTX∼14.8% and DOX∼9.4%) with a precise ratio of PTX and DOX to realize the synchronized and controlled release. The mixed micelle has an average size of 93.3nm with a narrow distribution, suitable for passive targeting to tumor tissues by the EPR effect. In vitro release profile and in vitro anticancer results show the mixed micelles have obvious redox-sensitive release properties in reducing environment and have a significant cytotoxicity to A549 and B16 cells. Importantly, in vivo study shows the mixed micelles have no obvious side effect on mice compared to free PTX/DOX samples during the treatment. Therefore, the constructed redox-sensitive mixed micelle is a promising drug delivery system for cancer therapy.

Biodegradable polyurethane micelles with pH and reduction responsive properties for intracellular drug delivery

Polyurethane micelles with disulfide linkage located at the interface of hydrophilic shell and hydrophobic core (PU-SS-I) have been shown enhanced drug release profiles. However, the payloads could not be released completely. The occurrence of aggregation of hydrophobic cores upon shedding hydrophilic PEG coronas was considered as the reason for the incomplete release. To verify the above hypothesis and to develop a new polyurethane based micelles with dual stimuli respond properties and controllable location of pH and reduction responsive groups in the PU main chains, a tertiary amine was incorporated into the hydrophobic core PU-SS-I, which resulted polyurethane with both reduction and pH sensitive properties (PU-SS-N). Biodegradable polyurethane with only disulfide linkages located between the hydrophilic PEG segment and the hydrophobic PCL segments (PU-SS-I) and polyurethane with only pH sensitive tertiary amine at the hydrophobic core (PU-N-C) were used as comparisons. Paclitaxel (PTX) was chosen as mode hydrophobic drug to evaluate the loading and redox triggered release profiles of the PU micelles. It was demonstrated that PU-SS-N micelles disassembled instantly at the presence of 10mM GSH and at an acidic environment (pH=5.5), which resulted the nearly complete release (~90%) of the payloads within 48h, while about ~70% PTX was released from PU-SS-I and PU-SS-N micelles at neutral environment (pH=7.4) with the presence of 10mM GSH. The rapid and complete redox and pH stimuli release properties of the PU-SS-N nanocarrier will be a promising anticancer drug delivery system to ensure sufficient drug concentration to kill the cancer cells and to prevent the emergency of MDR. The in vitro cytotoxicity and cell uptake of the PTX-loaded micelles was also assessed in H460 and HepG2 cells.

Precise control of drug loading and release of an NSAID–polymer conjugate for long term osteoarthritis intra-articular drug delivery

The synthesis of biocompatible polymer diclofenac conjugates (PDCs) that have a high drug loading and high degree of control over diclofenac (DCF) release is described.

Surface charge switchable and core cross-linked polyurethane micelles as a reduction-triggered drug delivery system for cancer therapy

The core cross-linked polyurethane micelles with redox sensitive and pH-responsive surface charge switchable properties were prepared by using diisocyanates as crosslinkers and studied as anticancer drug carriers.

Fully glutathione degradable waterborne polyurethane nanocarriers: Preparation, redox-sensitivity, and triggered intracellular drug release

Polyurethanes are important class of biomaterials that are extensively used in medical devices. In spite of their easy synthesis, polyurethanes that are fully degradable in response to the intracellular reducing environment are less explored for controlled drug delivery. Herein, a novel glutathione degradable waterborne polyurethane (WPU) nanocarrier for redox triggered intracellular delivery of a model lipophilic anticancer drug, doxorubicin (DOX) is reported. The WPU was prepared from polyaddition reaction of isophorone diisocyanate (IPDI) and a novel linear polyester polyol involving disulfide linkage, disulfide labeled chain extender, dimethylolpropionic acid (DMPA) using dibutyltin dilaurate (DBTDL) as a catalyst. The resulting polyurethane self-assembles into nanocarrier in water. The dynamic light scattering (DLS) measurements and scanning electron microscope (SEM) revealed fast swelling and disruption of nanocarriers under an intracellular reduction-mimicking environment. The in vitro release studies showed that DOX was released in a controlled and redox-dependent manner. MTT assays showed that DOX-loaded WPU had a high in vitro antitumor activity in both HDF noncancer cells and MCF- 7 cancer cells. In addition, it is found that the blank WPU nanocarriers are nontoxic to HDF and MCF-7 cells even at a high concentration of 2mg/mL. Hence, nanocarriers based on disulfide labeled WPU have appeared as a new class of biocompatible and redox-degradable nanovehicle for efficient intracellular drug delivery.

Facile Synthesis of Reductively Degradable Biopolymers Using Cystamine Diisocyanate as a Coupling Agent

Reductively degradable biopolymers have emerged as a unique class of smart biomedical materials. Here, a functional coupling agent, cystamine diisocyanate (CDI), was designed to offer a facile access to reductively degradable biopolymers via polycondensation with various diols. CDI was readily obtained with a decent yield of 46% by reacting cystamine dihydrochloride with triphosgene. The polycondensation of oligo(ethylene glycol) diol (Mn = 0.4 or 1.5 kg/mol) or oligo(ε-caprolactone) diol (Mn = 0.53 kg/mol) with CDI in N,N-dimethylformamide at 60 °C using dibutyltin dilaurate as a catalyst afforded reductively degradable poly(ethylene glycol) (SSPEG, Mn = 6.2-76.8 kg/mol) or poly(ε-caprolactone) (SSPCL, Mn = 6.8-16.3 kg/mol), in which molecular weights were well controlled by diol/CDI molar ratios. Moreover, PEG-SSPCL-PEG triblock copolymers could be readily prepared by reacting dihydroxyl-terminated SSPCL with PEG-isocyanate derivative. PEG-SSPCL-PEG with an Mn of 5.0-16.3-5.0 kg/mol formed small-sized micelles with an average diameter of about 85 nm in PB buffer. The in vitro release studies using doxorubicin (DOX) as a model drug showed that, in sharp contrast to reduction-insensitive PEG-PCL(HDI)-PEG controls, drug release from PEG-SSPCL-PEG micelles was fast and nearly complete in 24 h under a reductive condition containing 10 mM glutathione. The confocal microscopy experiments in drug-resistant MCF-7 cells (MCF-7/ADR) displayed efficient cytoplasmic DOX release from PEG-SSPCL-PEG micelles. MTT assays revealed that DOX-loaded PEG-SSPCL-PEG micelles were much more potent against MCF-7/ADR cells than reduction-insensitive PEG-PCL(HDI)-PEG controls (IC50: 6.3 vs 55.4 μg/mL). It should further be noted that blank PEG-SSPCL-PEG micelles were noncytotoxic up to a tested concentration of 1 mg/mL. Hence, cystamine diisocyanate appears to be an innovative coupling agent that facilitates versatile synthesis of biocompatible and reductively degradable biopolymers.

A star-shaped amphiphilic block copolymer with dual responses: synthesis, crystallization, self-assembly, redox and LCST–UCST thermoresponsive transition

The micelles/aggregates that were self-assembled from a star-shaped copolymer presented redox-responsive behaviour and LCST–UCST thermoresponsive transition.

Biodegradable multi-blocked polyurethane micelles for intracellular drug delivery: the effect of disulfide location on the drug release profile

Polyurethane micelles with disulfide bonds positioned mainly either at the hydrophobic PCL junctions (PU-SS-C) or at the connections between the hydrophilic PEG and hydrophobic PCL blocks (PU-SS-I) were developed as a antitumor drug carriers.

Biodegradable pH-sensitive polyurethane micelles with different polyethylene glycol (PEG) locations for anti-cancer drug carrier applications

Biodegradable pH sensitive polyurethane micelles with a dense brush like coating of PEG were prepared. The PTX-loaded PEG-g-PU-3 micelles exhibited potent cytotoxicity against H460 cancer cells compared to PEG-b-PU-3 and PEG-c-PU-3 micelles.

Reduction-responsive modification-induced higher efficiency for attenuation of tumor metastasis of low molecular weight heparin functionalized liposomes

Higher efficiency of attenuation of tumor metastasis was achievedviareduction-responsive modification of low molecular weight heparin on doxorubicin liposomes.

Folate-containing reduction-sensitive lipid-polymer hybrid nanoparticles for targeted delivery of doxorubicin

The development and evaluation of folate-targeted and reduction-triggered biodegradable nanoparticles are introduced to the research on targeted delivery of doxorubicin (DOX). This type of folate-targeted lipid-polymer hybrid nanoparticles (FLPNPs) is comprised of a poly(D,L-lactide-co-glycolide) (PLGA) core, a soybean lecithin monolayer, a monomethoxy-poly(ethylene glycol)-S-S-hexadecyl (mPEG-S-S-C16) reduction-sensitive shell, and a folic acid-targeted ligand. FLPNPs exhibited high size stability but fast disassembly in a simulated cancer cell reductive environment. The experiments on the release process in vitro revealed that as a reduction-sensitive drug delivery system, FLPNPs released DOX faster in the presence of 10 mM dithiothreitol (DTT). Results from flow cytometry, confocal image and in vitro cytotoxicity assays revealed that FLPNPs further enhanced cell uptake and generated higher cytotoxicity against human epidermoid carcinoma in the oral cavity than non-targeted redox-sensitive and targeted redox-insensitive controls. Furthermore, in vivo animal experiments demonstrated that systemic administration of DOX-loaded FLPNPs remarkably reduced tumor growth. Experiments on biodistribution of DOX-loaded FLPNPs showed that an increasing amount of DOX accumulated in the tumor. Therefore, FLPNPs formulations have proved to be a stable, controllable and targeted anticancer drug delivery system.

Biocompatible and bioreducible micelles fabricated from novel α-amino acid-based poly(disulfide urethane)s: design, synthesis and triggered doxorubicin release

Novel α-amino acid-based poly(disulfide urethane)s have been developed for the construction of smart triblock copolymer micelles that show good biocompatibility, fast reductive degradation, and triggered intracellular drug release behavior.

pH and reduction dual responsive cross-linked polyurethane micelles as an intracellular drug delivery system

pH- and reduction-responsive disulfide-crosslinked polyurethane micelles (CL-PUMs) were developed. The CL-PUMs remained stable in normal PBS while selectively swelled or decomposed in response to weakly acidic environment or reducing agent.