Design, Synthesis, and Acid-Responsive Disassembly of Shell-Sheddable Block Copolymer Labeled with Benzaldehyde Acetal Junction

Smart nanoassemblies degradable through the cleavage of acid-labile linkages have attracted significant attention because of their biological relevance found in tumor tissues. Despite their high potential to achieve controlled/enhanced drug release, a systematic understanding of structural factors that affect their pH sensitivity remains challenging, particulary in the consruction of effective acid-degradable shell-sheddable nanoassemblies. Herein, the authors report the synthesis and acid-responsive degradation through acid-catalyzed hydrolysis of three acetal and ketal diols and identify benzaldehyde acetal (BzAA) exhibiting optimal hydrolysis profiles in targeted pH ranges to be a suitable candidate for junction acid-labile linkage. The authors explore the synthesis and aqueous micellization of well-defined poly(ethylene glycol)-based block copolymer bearing BzAA linkage covalently attached to a polymethacrylate block for the formation of colloidally-stable nanoassemblies with BzAA groups at core/corona interfaces. Promisingly, the investigation on acid-catalyzed hydrolysis and disassembly shows that the formed nanoassemblies meet the criteria for acid-degradable shell-sheddable nanoassemblies: slow degradation at tumoral pH = 6.5 and rapid disassembly at endo/lysosomal pH = 5.0, while colloidal stability at physiological pH = 7.4. This work guides the design principle of acid-degradable shell-sheddable nanoassemblies bearing BzAA at interfaces, thus offering the promise to address the PEG dilemma and improve endocytosis in tumor-targeting drug delivery.

Recent Advances in the Application of ATRP in the Synthesis of Drug Delivery Systems

Advances in atom transfer radical polymerization (ATRP) have enabled the precise design and preparation of nanostructured polymeric materials for a variety of biomedical applications. This paper briefly summarizes recent developments in the synthesis of bio-therapeutics for drug delivery based on linear and branched block copolymers and bioconjugates using ATRP, which have been tested in drug delivery systems (DDSs) over the past decade. An important trend is the rapid development of a number of smart DDSs that can release bioactive materials in response to certain external stimuli, either physical (e.g., light, ultrasound, or temperature) or chemical factors (e.g., changes in pH values and/or environmental redox potential). The use of ATRPs in the synthesis of polymeric bioconjugates containing drugs, proteins, and nucleic acids, as well as systems applied in combination therapies, has also received considerable attention.

Perfluorocarbon Nanodroplets for Dual Delivery with Ultrasound/GSH-Responsive Release of Model Drug and Passive Release of Nitric Oxide

Nitric oxide (NO) plays a critical role as an important signaling molecule for a variety of biological functions, particularly inhibiting cell proliferation or killing target pathogens. To deliver active radical NO gaseous molecule whose half-life is a few seconds in a stable state, the design and development of effective exogenous NO supply nanocarriers are essential. Additionally, the delivery of desired drugs with NO can produce synergistic effects. Herein, we report a new approach that allows for the fabrication of dual ultrasound (US)/glutathione (GSH)-responsive perfluorocarbon (PFC) nanodroplets for the controlled release of model drug and passive release of safely incorporated NO. The approach centers on the synthesis of a disulfide-labeled amphiphilic block copolymer and its use as a GSH-degradable macromolecular emulsifier for oil-in-water emulsification process of PFC. The fabricated PFC nanodroplets are colloidally stable and enable the encapsulation of both NO and model drugs. Encapsulated drug molecules are synergistically released when ultrasound and GSH are presented, while NO molecules are passively but rapidly released. Our preliminary results demonstrate that the approach is versatile and can be extended to not only GSH-responsive but also other stimuli-responsive block copolymers, thereby allowing for the fabrication of broad choices of stimuli-responsive (smart) PFC-nanodroplets in aqueous solution for dual delivery of drug and NO therapeutics.

High-Throughput Routes to Biomaterials Discovery

Many existing clinical treatments are limited in their ability to completely restore decreased or lost tissue and organ function, an unenviable situation only further exacerbated by a globally aging population. As a result, the demand for new medical interventions has increased substantially over the past 20 years, with the burgeoning fields of gene therapy, tissue engineering, and regenerative medicine showing promise to offer solutions for full repair or replacement of damaged or aging tissues. Success in these fields, however, inherently relies on biomaterials that are engendered with the ability to provide the necessary biological cues mimicking native extracellular matrixes that support cell fate. Accelerating the development of such "directive" biomaterials requires a shift in current design practices toward those that enable rapid synthesis and characterization of polymeric materials and the coupling of these processes with techniques that enable similarly rapid quantification and optimization of the interactions between these new material systems and target cells and tissues. This manuscript reviews recent advances in combinatorial and high-throughput (HT) technologies applied to polymeric biomaterial synthesis, fabrication, and chemical, physical, and biological screening with targeted end-point applications in the fields of gene therapy, tissue engineering, and regenerative medicine. Limitations of, and future opportunities for, the further application of these research tools and methodologies are also discussed.

Imidazole-Mediated Dual Location Disassembly of Acid-Degradable Intracellular Drug Delivery Block Copolymer Nanoassemblies

Acid-degradable (or acid-cleavable) polymeric nanoassemblies have witnessed significant progress in anti-cancer drug delivery. However, conventional nanoassemblies designed with acid-cleavable linkages at a single location have several challenges, such as, sluggish degradation, undesired aggregation of degraded products, and difficulty in controlled and on-demand drug release. Herein, a strategy that enables the synthesis of acid-cleavable nanoassemblies labeled with acetaldehyde acetal groups in both hydrophobic cores and at core/corona interfaces, exhibiting synergistic response to acidic pH at dual locations and thus inducing rapid drug release is reported. The systematic analyses suggest that the acid-catalyzed degradation and disassembly are further enhanced by decreasing copolymer concentration (i.e., increasing proton/acetal mole ratio). Moreover, incorporation of acid-ionizable imidazole pendants in the hydrophobic cores improve the encapsulation of doxorubicin, the anticancer drug, through π-π interactions and enhance the acid-catalyzed hydrolysis of acetal linkages situated in the dual locations. Furthermore, the presence of the imidazole pendants induce the occurrence of core-crosslinking that compensates the kinetics of acetal hydrolysis and drug release. These results, combined with in vitro cell toxicity and cellular uptake, suggest the versatility of the dual location acid-degradation strategy in the design and development of effective intracellular drug delivery nanocarriers.

Cascade-Targeting of Charge-Reversal and Disulfide Bonds Shielding for Efficient DOX Delivery of Multistage Sensitive MSNs-COS-SS-CMC

BACKGROUND

Although pH and redox sensitiveness have been extensively investigated to improve therapeutic efficiency, the effect of disulfide bonds location and pH-triggered charge-reversal on cascade-targeting still need to be further evaluated in cancer treatment with multi-responsive nanoparticles.

PURPOSE

The aim of this study was to design multi-responsive DOX@MSNs-COS-NN-CMC, DOX@MSNs-COS-SS-CMC and DOX@MSNs-COS-CMC-SS and systematically investigate the effects of disulfide bonds location and charge-reversal on the cancer cell specificity, endocytosis mechanisms and antitumor efficiency.

RESULTS

In vitro drug release rate of DOX@MSNs-COS-SS-CMC in tumor environments was 7-fold higher than that under normal physiological conditions after 200 h. Furthermore, the fluorescence intensity of DOX@MSNs-COS-SS-CMC and DOX@MSNs-COS-CMC-SS was 1.9-fold and 1.3-fold higher than free DOX at pH 6.5 and 10 mM GSH. In addition, vesicular transport might be a factor that affects the uptake efficiency of DOX@MSNs-COS-SS-CMC and DOX@MSNs-COS-CMC-SS. The clathrin-mediated endocytosis and endosomal escape of DOX@MSNs-COS-SS-CMC enhanced cellular internalization and preserved highly controllable drug release into the perinuclear of HeLa cells. DOX@MSNs-COS-SS-CMC exhibited a synergistic chemotherapy in preeminent tumor inhibition and less side effects of cardiotoxicity.

CONCLUSION

The cascade-targeting of charge-reversal and disulfide bonds shielding would be a highly personalized strategy for cervical cancer treatment.

Stimuli-Responsive Cycloaurated "OFF-ON" Switchable Anion Transporters

Anion transporters have shown potential application as anti-cancer agents that function by disrupting homeostasis and triggering cell death. In this research article we report switchable anion transport by gold complexes of anion transporters that are "switched on" in situ in the presence of the reducing agent GSH by decomplexation of gold. GSH is found in higher concentrations in tumors than in healthy tissue and hence this approach offers a strategy to target these systems to tumors.

Dual Reduction/Acid-Responsive Disassembly and Thermoresponsive Tunability of Degradable Double Hydrophilic Block Copolymer

We report a thermoresponsive double hydrophilic block copolymer degradable in response to dual reduction and acidic pH at dual locations. The copolymer consists of a poly(ethylene oxide) block covalently connected through an acid-labile acetal linkage with a thermoresponsive polymethacrylate block containing pendant oligo(ethylene oxide) and disulfide groups. The copolymer undergoes temperature-driven self-assembly in water to form nanoassemblies with acetal linkages at the core/corona interface and disulfide pendants in the core, exhibiting dual reduction/acid responses at dual locations. The physically assembled nanoaggregates are converted to disulfide-core-crosslinked nanogels through disulfide-thiol exchange reaction, retaining enhanced colloidal stability, yet degraded to water-soluble unimers upon reduction/acid-responsive degradation. Further, the copolymer exhibits improved tunability of thermoresponsive property upon the cleavage of junction acetal and pendant disulfide linkages individually and in combined manner. This work suggests that dual location dual reduction/acid-responsive degradation is a versatile strategy toward effective drug delivery exhibiting disulfide-core-crosslinking capability and disassembly as well as improved thermoresponsive tunability.

Controlled Microfluidic Synthesis of Biological Stimuli-Responsive Polymer Nanoparticles

Microfluidic flow-directed self-assembly of biological stimuli-responsive block copolymers is demonstrated with dual-location cleavable linkages at the junction between hydrophilic and hydrophobic blocks and on pendant group within the hydrophobic blocks. On-chip self-assembly within a two-phase microfluidic reactor forms various "DualM" polymer nanoparticles (PNPs), including cylinders and multicompartment vesicles, with sizes and morphologies that are tunable with manufacturing flow rate. Complex kinetically trapped intermediates between shear-dependent states provide the most detailed mechanism to date of microfluidic PNP formation in the presence of flow-variable high shear. Glutathione (GSH)-triggered changes in PNP size and internal structure depend strongly on the initial flow-directed size and internal structure. Upon incubation in GSH, flow-directed PNPs with smaller average sizes showed a faster hydrodynamic size increase (attributed to junction cleavage) and those with higher excess Gibbs free energy showed faster inner compartment growth (attributed to pendant cleavage). These results demonstrate that the combination of chemical control of the location of biologically responsive linkages with microfluidic shear processing offers promising routes for tunable "smart" polymeric nanomedicines.

Thiol-reactive thiosulfonate group containing copolymers: facile entry to disulfide-mediated polymer conjugation and redox-responsive functionalizable networks

Herein, we report a synthetic approach to thiol-reactive polymers containing methanethiosulfonate groups as side chains, and demonstrate their application in post-polymerization functionalization through reversible disulfide linkages.

Hydrogen Peroxide and Glutathione Dual Redox-Responsive Nanoparticles for Controlled DOX Release

Polymer nanoparticulate drug delivery systems that respond to reactive oxygen species (ROS) and glutathione (GSH) simultaneously at biologically relevant levels hold great promise to improve the therapeutic efficacy to cancer cells with reduced side effects of chemo drugs. Herein, a novel redox dual-responsive amphiphilic block copolymer (ABP) that consists of a hydrophilic poly (ethylene oxide) block and a hydrophobic block bearing disulfide linked phenylboronic ester group as pendant is synthesized, and the DOX loaded nanoparticles (BSN-DOX) based on ABPs with varied hydrophobic block length are fabricated for DOX delivery. The self-immolative leaving reaction of phenylboronic ester triggered by extracellular ROS and the cleavage of disulfide linkages induced by intracellular GSH both lead to rapid DOX release from BSN-DOX, resulting in an on-demand DOX release. Moreover, BSN-DOX show better tumor inhibition and lower side effects in vivo compared with free drug.

Synthesis of crosslinkable diblock terpolymers PDPA-b-P(NMS-co-OEG) and preparation of shell-crosslinked pH/redox-dual responsive micelles as smart nanomaterials

Crosslinked polymer nanomaterials have attracted great attention due to their stability and highly controllable drug delivery; herein, a series of well-defined amphiphilic PDPA-b-P(NMS-co-OEG) diblock terpolymers (P1–P3) were designed and prepared via RAFT polymerization and were self-assembled into non-cross-linked (NCL) nanomicelles, which were further prepared into shell-cross-linked (SCL) micelles via cystamine-based in situ shell cross-linking. Using P3 as an optimized polymer, SCL-P3 micelles were prepared, which demonstrated remarkable pH/redox-dual responsive behaviour. For drug delivery, camptothecin (CPT)-loaded SCL-P3 micelles were prepared and showed much higher CPT-loading capability than their NCL-P3 counterparts. Notably, the SCL-P3 micelles showed good synergistic pH/redox-dual responsive CPT release properties, making them potential “smart” nanocarriers for drug delivery.

A series of well-defined amphiphilic PDPA-b-P(NMS-co-OEG) diblock terpolymers were prepared via RAFT polymerization and self-assembled into non-cross-linked nanomicelles, and then shell-cross-linked micelles via cystamine-based in situ shell cross-linking.

Disassembly and tumor-targeting drug delivery of reduction-responsive degradable block copolymer nanoassemblies

Review on recent strategies to synthesize novel disulfide-containing reductively-degradable block copolymers and their nanoassemblies as being classified with the number, position, and location of the disulfide linkages toward effective tumor-targeting intracellular drug delivery exhibiting enhanced release of encapsulated drugs.

Facile Strategies to Synthesize Dual Location Dual Acidic pH/Reduction-Responsive Degradable Block Copolymers Bearing Acetal/Disulfide Block Junctions and Disulfide Pendants

We report new dual acidic pH/reduction-responsive degradable amphiphilic block copolymers featured with dual acidic pH-labile acetal linkage and a reductively-cleavable disulfide bond at the hydrophilic/hydrophobic block junction as well as pendant disulfide bonds in the hydrophobic block. Centered on the use of a macroinitiator approach, three strategies utilize the combination of atom transfer radical polymerization and reversible addition fragmentation chain transfer polymerization in a sequential or concurrent mechanism, along with facile coupling reactions. Combined structural analysis with dual-stimuli-responsive degradation investigation allows better understanding of the architectures and orthogonalities of the formed block copolymers as a diblock or a triblock copolymer. Our study presents the development of effective synthetic strategies to well-defined multifunctional amphiphilic block copolymers that exhibit dual-stimuli-responsive degradation at dual location (called the DL-DSRD strategy), thus potentially promising as nanoassemblies for effective drug delivery.

Intracellular GSH-activated galactoside photosensitizers for targeted photodynamic therapy and chemotherapy

Ligand-targeted cancer therapeutics has been developed to minimize non-specific cytotoxicity via ligand-drug conjugates during the past few decades. We present here the design and synthesis of a GSH-activated amphiphilic photosensitizer conjugated with galactose (TPP-S-S-Gal) for targeted photodynamic therapy. Furthermore, the galactoside photosensitizer as supramolecular amphiphiles can self-assemble into micelles, which can be applied in integrative cancer treatment with chemotherapy drugs such as camptothecin (CPT) encapsulated in the hydrophobic core of micelles. Upon reaction with free thiol GSH that is relatively abundant in tumor cells, disulfide bond cleavage occurs as well as the active photosensitizer TPP and chemotherapy drug CPT release, which can cause cell apoptosis. The in vitro biological assessment of TPP-S-S-Gal micelles against the A549 cell line was evaluated by MTT assay, flow cytometry and confocal scanning laser microscopy, respectively. According to the MTT assay, TPP-S-S-Gal micelles exhibited low dark toxicity and efficient integrative efficacy of PDT and chemotherapy towards A549 cells after light irradiation.

Facile Fabrication of a Modular "Catch and Release" Hydrogel Interface: Harnessing Thiol-Disulfide Exchange for Reversible Protein Capture and Cell Attachment

Surfaces engineered to "specifically capture" and "release on demand" analytes ranging from biomolecules to cells find niche applications in areas such as diagnostics and detection. Utilization of a disulfide-based linker as a building block allows fabrication of a novel hydrogel-based platform that incorporates a "catch and release" attribute. Hydrogels incorporating pyridyl disulfide groups as thiol-reactive handles were prepared by photopolymerization in the presence of a poly(ethylene glycol) (PEG)-based cross-linker. A range of bulk and micropatterned hydrogels with varying amounts of the reactive group were prepared using PEG-based monomers with different chain lengths. Thiol-containing molecules were conjugated to these hydrogels through the thiol-disulfide exchange reaction under ambient conditions with high efficiencies, as determined by UV-vis spectroscopy. Facile conjugation of a thiol-containing fluorescent dye, namely 4,4-difluoro-1,3,5,7-tetramethyl-8-[(10-mercapto)]-4-bora-3 a,4 a-diaza- s-indacene, was demonstrated, followed by its effective cleavage in the presence of dithiothreitol (DTT), a thiol-containing disulfide-reducing agent. Conjugation of a biotin-containing ligand onto the hydrogels allowed specific binding of protein extravidin when exposed to a mixture of extravidin and bovine serum albumin. The bound protein could be released from the hydrogel by simple exposure to a DTT solution. Likewise, hydrogels modified with a cell-adhesive peptide unit containing the RGD sequence acted as favorable substrates for cellular attachment. Incubation of these cell-attached hydrogel surfaces in a DTT-containing solution leads to facile detachment of cells from the surfaces, while retaining a high level of cell viability. It can be envisioned that the benign nature of these hydrogels, their facile fabrication, and modular functionalization will make them attractive platforms for many applications.

Hydroxyl-triggered fluorescence for location of inorganic materials in polymer-matrix composites

We present a locating technique for inorganic materials in polymer-matrix composites through a post-labeling approach based on specific covalent binding.

There is a long-standing challenge to realize in situ visualization of incorporated inorganic materials in organic–inorganic composites in a post-labeling manner, owing to the lack of specific fluorescent organic dye molecules for targeting inorganic materials. Herein, we observe that the specific covalent B–O binding between the hydroxyl groups of inorganic materials and commercially available aggregation-induced emission (AIE)-active boronic acid could lead to the formation of highly emissive solid-state fluorescent composite materials. The hydroxyl-triggered luminescent probe may serve as a practical method for in situ location of incorporated inorganic materials in polymer-matrix composites by simply dipping the composite film in boronic acid-modified AIE solution. This present work offers a non-invasive avenue to locate inorganic materials which possess hydroxyl-groups in polymer-matrix composites, thereby developing a convenient screening strategy for assessing the advanced properties of composites. This strategy can also be extended to the targeted tracing of other inorganic materials with inherent and functionalized carboxyl, amino, sulfhydryl and other groups via tuning the binding affinity between the inorganic materials and luminescent molecules.

Preparation of multilocation reduction-sensitive core crosslinked folate-PEG-coated micelles for rapid release of doxorubicin and tariquidar to overcome drug resistance

Herein, we prepared folate-targeting core crosslinked polymeric micelles (CCL/FA) containing multiple disulfide bonds located at the interface and core of the micelles to co-deliver doxorubicin (DOX) and the P-glycoprotein (P-gp) inhibitor tariquidar (TQR) for reversing drug resistance. The stability and redox-responsive behavior of the CCL/FA micelles was evaluated through the changes in morphology, molecular weight and hydrodynamic size. On the one hand, the micelles possessed good stability, which led to the suppression of drug release from the CCL micelles in the physiological environment. On the other hand, under reductive conditions, the CCL micelles collapsed rapidly and accelerated drug release markedly. In vitro cytotoxicity measurements, combined with confocal laser scanning microscopy (CLSM) and flow cytometry, confirmed that the dual-drug-loaded micelles exhibited obviously higher cytotoxicity to MCF-7/ADR-resistant cells than free DOX · HCl, single-drug loaded CCL micelles and nontargeted CCL micelles. The results imply that co-delivering DOX and TQR by CCL/FA micelles may be a promising way of overcoming multidrug resistance in tumor treatments.

Fabrication of Two-Dimensional Arrays of Diameter-Tunable PS-b-P2VP Nanowires at the Air/Water Interface

Composite thin films with well-defined and parallel nanowires were fabricated from the binary blends of a diblock copolymer polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) and several homopolystyrenes (h-PSs) at the air/liquid interface through a facile technique, which involves solution self-assembly, interface adsorption, and further self-organization processes. It was confirmed that the nanowires that appeared at the air/water interface came from the cylindrical micelles formed in solution. Interestingly, the diameters of the nanowires are uniform and can be tuned precisely from 45 to 247 nm by incorporating the h-PS molecules into the micellar core. This parallel alignment of the nanowires has potential applications in optical devices and enables the nanowires to be used as templates to prepare functional nanostructures. The extent to which h-PS molecules with different molecular weights are able to influence the diameter control of the nanowires was also systematically investigated.

Rosin-based block copolymer intracellular delivery nanocarriers with reduction-responsive sheddable coronas for cancer therapy

Rosin-based, reduction-responsive block copolymer-based nanocarriers exhibiting excellent colloidal stability enabling the delivery of anticancer drugs to cancerous tissues for the enhanced release of encapsulated drugs, offering great versatility as intracellular drug-delivery nanocarriers for cancer therapy.

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.

Zwitterionic nanoparticles constructed with well-defined reduction-responsive shell and pH-sensitive core for "spatiotemporally pinpointed" drug delivery

Enabling nanocarriers to complete the sophisticated journey from the initial injection site to the targeted tumor cells and achieve "spatiotemporally pinpointed" drug release intracellularly is a challenging task in anticancer drug delivery. Herein, versatile shell-cross-linked nanoparticles (SCNPs) were prepared by one-step assembly of triblock zwitterionic copolymers, polycarboxybetaine methacrylate-block-poly(N-(2-(2-pyridyl disulde) ethyl methacrylamide-block-poly(2-(diisopropylamino) ethyl methacrylate) (PCB-b-PDS-b-PDPA, termed as PCSSD), which was well-defined via reversible additive fragment transfer (RAFT) polymerization, followed by functionalization with Arg-Gly-Asp (RGD). Thus, the RGD-PCSSD SCNPs cooperatively combine the ultra pH-sensitive PDPA core for efficient drug loading and pH-responsive drug release, the disulfide-cross-linked PDS shell that prevents premature drug release, the zwitterionic PCB corona to stabilize the SCNPs and prolong its systemic circulation, the RGD ligand for active tumor targeting and receptor-mediated endocytosis. Doxorubicin (DOX) was loaded as a model medicine (termed as RGD-PCSSD/DOX SCNPs). The dual-sensitivity studies showed that the pH-sensitivity of PDPA core could be adjusted by the shell-cross-linking density, accompanied by better control over premature drug release. Furthermore, results obtained by flow cytometry and fluorescence microscopy analysis demonstrated that once the RGD-PCSS10D/DOX SCNPs were internalized into tumor cells via receptor-mediated endocytosis, boost drug release was observed with considerable cytotoxicity in vitro. The results of ex vivo imaging studies further confirmed the successful drug delivery from the injection site to the tumor tissue. In summary, the well-constructed RGD-PCSS10D/DOX SCNPs with cooperative multifunctionality showed great potential as novel nanocarriers for tumor targeted anticancer drug delivery.

Dual-stimuli-responsive micelle of an ABC triblock copolymer bearing a redox-cleavable unit and a photocleavable unit at two block junctions

The design, synthesis, and study of a new dual-stimuli-responsible ABC-type triblock copolymer are reported. Using ATRP and click coupling reaction, the prepared copolymer is composed of poly(ethylene oxide) (PEO), polystyrene (PS), and poly[2-(dimethylamino)ethylmethacrylate] (PDMAEMA) and features a redox-cleavable disulfide junction between the PEO and PS blocks as well as a photocleavable o-nitrobenzyl linkage between the PS and PDMAEMA blocks. This design allows the triblock copolymer to respond to both a reducing agent like dithiothreitol (DTT) and UV light, while having the minimum number of stimuli-reactive moieties in the copolymer structure (two per chain). The disruption of the triblock copolymer micelles in aqueous solution was examined under the action of either UV light or DTT alone or combined use of the two stimuli. It was found that the removal of one type of hydrophilic polymer chains from the water-soluble corona of the micelles with a hydrophobic PS core, that is, either redox-cleaved PEO or photocleaved PDMAEMA, could only result in a limited destabilization effect on the dispersion of the micelles. Severe aggregation of the polymer was observed only by applying the two stimuli converting the triblock copolymer onto three homopolymers. By monitoring the quenching by aqueous medium of the fluorescence of a hydrophobic dye (Nile Red) loaded in the triblock copolymer micelles, the effect on the payload release was also investigated of the different ways in which the micelles can be disrupted by the stimuli.