Photothermally Controllable Cytosolic Drug Delivery Based On Core–Shell MoS₂‑Porous Silica Nanoplates

Single-layered molybdenum sulfide (MoS₂) displays strong photothermal properties, but low colloidal stability in aqueous solution prevents its biomedical application as a functional drug delivery carrier. We report a photothermally controllable nanoplate consisting of porous silica-coated, single-layered MoS₂, modified with poly­(ethylene glycol) (PEG). Silica and PEG enhanced stability and maintained the single layer structure of MoS₂ for over a month. A representative anticancer drug, doxorubicin (DOX), was loaded into the silica structure and subsequent exposure to near-infrared irradiation facilitated both endosomal escape of the carrier and the release of DOX. DOX-loaded, silica-coated, single-layered MoS₂ (DOX–PSMS–PEG) showed better therapeutic effect against liver and colon cancer compared than free DOX did; a result probably attributable to the combined effects of photothermally facilitated endosomal escape and the vulnerability of cancer cells to localized heating. These studies suggest that considerable new opportunities may exist for spatiotemporally controllable drug delivery systems based on single-layered MoS₂

Tumor-Homing, Size-Tunable Clustered Nanoparticles for Anticancer Therapeutics

We present herein a pH-responsive dynamic DNA nanocluster based on gold nanoparticles with highly packed nucleic acid assembly and evaluate its potential as a drug delivery vehicle with tumor-specific accumulation. Each gold nanoparticle was readily functionalized with various functional DNA sequences; in particular, we modified the surface of gold nanoparticles with bcl-2 antisense and i-motif binding sequences. Clustering of the gold nanoparticles induced by hybridization of each DNA sequence <i>via</i> i-motif DNA provided tumor targeting and drug loading capabilities. After cellular uptake, the drug was released by disassembly of the gold nanoparticle cluster into single gold nanoparticles in response to the pH decrease in the late endosome. Furthermore, the antiapoptotic Bcl-2 protein was down-regulated by the antisense-modified gold nanoparticles; thus, drug-mediated apoptosis was significantly accelerated by sensitizing the cancer cells to the drug. Our size-tunable clustered nucleic acid-grafted gold nanoparticles provide tumor homing in the blood circulation and are thus a potential multifunctional therapeutic agent <i>in vivo</i> as well as <i>in vitro</i>

i‑Motif-Driven Au Nanomachines in Programmed siRNA Delivery for Gene-Silencing and Photothermal Ablation

The present work illustrates unique design, construction and operation of an i-motif-based DNA nanomachine templated on gold nanoparticles (AuNPs), which utilizes pH-responsive dynamic motion of i-motif DNA strands and aggregational behavior of AuNPs to elicit programmed delivery of therapeutic siRNA. The pH-sensitive nucleic acids immobilized on the AuNPs consisted of three functional segments, <i>i.e.</i>, an i-motif DNA, an overhanging linker DNA and a therapeutic siRNA. At neutral pH, the i-motif DNA is hybridized with the overhanging linker DNA segment of the therapeutic siRNA. However, in endosomal acidic pH, the i-motif DNA forms interstrand tetraplex, which could induce cluster formation of AuNPs resulting in endosomal escape of AuNP clusters, and produce a high gene silencing efficiency by releasing siRNA in the cytosol. Furthermore, the cluster formation of AuNPs accelerated photothermal ablation of cells when irradiated with laser. Precise and synchronized biomechanical motion in subcellular microenvironment is realized through judicious integration of pH-responsive behavior of the i-motif DNA and AuNPs, and meticulous designing of DNA

Photothermally Triggered Cytosolic Drug Delivery <i>via</i> Endosome Disruption Using a Functionalized Reduced Graphene Oxide

Graphene oxide has unique physiochemical properties, showing great potential in biomedical applications. In the present work, functionalized reduced graphene oxide (PEG-BPEI-rGO) has been developed as a nanotemplate for photothermally triggered cytosolic drug delivery by inducing endosomal disruption and subsequent drug release. PEG-BPEI-rGO has the ability to load a greater amount of doxorubicin (DOX) than unreduced PEG-BPEI-GO <i>via</i> π–π and hydrophobic interactions, showing high water stability. Loaded DOX could be efficiently released by glutathione (GSH) and the photothermal effect of irradiated near IR (NIR) in test tubes as well as in cells. Importantly, PEG-BPEI-rGO/DOX complex was found to escape from endosomes after cellular uptake by photothermally induced endosomal disruption and the proton sponge effect, followed by GSH-induced DOX release into the cytosol. Finally, it was concluded that a greater cancer cell death efficacy was observed in PEG-BPEI-rGO/DOX complex-treated cells with NIR irradiation than those with no irradiation. This study demonstrated the development of the potential of a PEG-BPEI-rGO nanocarrier by photothermally triggered cytosolic drug delivery <i>via</i> endosomal disruption

Additional file 1: of GScluster: network-weighted gene-set clustering analysis

Supplementary Material. This includes descriptions of GSAseq web server, gene-set collection method, network visualization and runtime of GScluster, and Supplementary Figure S2. (DOCX 1970 kb

<i>In Vivo</i> Photoacoustic Monitoring of Stem Cell Location and Apoptosis with Caspase-3-Responsive Nanosensors

Stem cell therapy has immense potential in a variety of regenerative medicine applications. However, clinical stem cell therapy is severely limited by challenges in assessing the location and functional status of implanted cells in vivo. Thus, there is a great need for longitudinal, noninvasive stem cell monitoring. Here we introduce a multidisciplinary approach combining nanosensor-augmented stem cell labeling with ultrasound guided photoacoustic (US/PA) imaging for the spatial tracking and functional assessment of transplanted stem cell fate. Specifically, our nanosensor incorporates a peptide sequence that is selectively cleaved by caspase-3, the primary effector enzyme in mammalian cell apoptosis; this cleavage event causes labeled cells to show enhanced optical absorption in the first near-infrared (NIR) window. Optimization of labeling protocols and spectral characterization of the nanosensor in vitro showed a 2.4-fold increase in PA signal from labeled cells during apoptosis while simultaneously permitting cell localization. We then successfully tracked the location and apoptotic status of mesenchymal stem cells in a mouse hindlimb ischemia model for 2 weeks in vivo, demonstrating a 4.8-fold increase in PA signal and spectral slope changes in the first NIR window under proapoptotic (ischemic) conditions. We conclude that our nanosensor allows longitudinal, noninvasive, and nonionizing monitoring of stem cell location and apoptosis, which is a significant improvement over current end-point monitoring methods such as biopsies and histological staining of excised tissue

Miktoarm Amphiphilic Block Copolymer with Singlet Oxygen-Labile Stereospecific β‑Aminoacrylate Junction: Synthesis, Self-Assembly, and Photodynamically Triggered Drug Release

Incorporation of a desired stimuli-responsive unit in a stereospecific manner at the specific location within a nonlinear block copolymer architecture is a challenging task in synthetic polymer chemistry. Herein, we report a facile and versatile method to synthesize AB₂ miktoarm block copolymers bearing a singlet oxygen (¹O₂)-labile regio and stereospecific β-aminoacrylate linkage with 100% <i>E</i>-configuration at the junction via a combination of amino-yne click chemistry and ring opening polymerization. Using this strategy, a series of ¹O₂-responsive AB₂ amphiphilic miktoarm (MA) copolymers composed of hydrophilic polyethylene glycol (PEG) as the A constituent and hydrophobic polycaprolactone (PCL) as the B constituent (MA-PEG-<i>b</i>-PCL₂) was synthesized by varying the block length of PCL. The self-assembly characteristics of these well-defined MA-PEG-<i>b</i>-PCL₂ copolymers in an aqueous condition were studied by solvent displacement and thin-film hydration method, and their morphologies were investigated using transmission electron microscopy. The copolymers formed spherical, cylindrical, or lamella morphologies, depending on the chain length and preparation conditions. A hydrophobic photosensitizer chlorin e6 (Ce6) and anticancer drug doxorubicin (DOX) were efficiently encapsulated into the hydrophobic core of MA-PEG-<i>b</i>-PCL₂ copolymer micelles. These coloaded micelles were taken up by human breast cancer (MDA-MB-231) cells. Upon red laser light irradiation, the ¹O₂-generated by the Ce6 induced photocleavage of the β-aminoacrylate moiety, leading to the dissociation of the micellar structure and triggered intracellular drug release for effective therapy. Overall, rapid disassembly upon ¹O₂ generation and subsequent controlled intracellular drug release suggested that these micelles bearing β-aminoacrylate linkage have a huge potential for on-demand drug delivery

<i>In Vivo</i> Photoacoustic Monitoring of Stem Cell Location and Apoptosis with Caspase-3-Responsive Nanosensors

Stem cell therapy has immense potential in a variety of regenerative medicine applications. However, clinical stem cell therapy is severely limited by challenges in assessing the location and functional status of implanted cells in vivo. Thus, there is a great need for longitudinal, noninvasive stem cell monitoring. Here we introduce a multidisciplinary approach combining nanosensor-augmented stem cell labeling with ultrasound guided photoacoustic (US/PA) imaging for the spatial tracking and functional assessment of transplanted stem cell fate. Specifically, our nanosensor incorporates a peptide sequence that is selectively cleaved by caspase-3, the primary effector enzyme in mammalian cell apoptosis; this cleavage event causes labeled cells to show enhanced optical absorption in the first near-infrared (NIR) window. Optimization of labeling protocols and spectral characterization of the nanosensor in vitro showed a 2.4-fold increase in PA signal from labeled cells during apoptosis while simultaneously permitting cell localization. We then successfully tracked the location and apoptotic status of mesenchymal stem cells in a mouse hindlimb ischemia model for 2 weeks in vivo, demonstrating a 4.8-fold increase in PA signal and spectral slope changes in the first NIR window under proapoptotic (ischemic) conditions. We conclude that our nanosensor allows longitudinal, noninvasive, and nonionizing monitoring of stem cell location and apoptosis, which is a significant improvement over current end-point monitoring methods such as biopsies and histological staining of excised tissue

Bioinspired Dual Stimuli-Responsive Membranous System with Multiple On–Off Gates

Stimuli-responsive polymers have been widely used for controlled release of several biomolecules. In general, a single stimulus among various stimuli, for instance, temperature, pH, or light, has been used for these polymers. Although some stimuli are applied together, one cannot control each stimulus independently at a given stimulus-responsive polymer. However, to mimic biological system like cell membrane, multiple on–off gates utilizing independent control of dual (or multiple) stimuli should be used. Here, we introduce a stimuli-responsive membrane controlled by two orthogonal stimuli. For this purpose, the top and the bottom parts of anodized aluminum oxide membrane walls are independently grafted by thermoresponsive poly­(<i>N</i>-isopropylacrylamide) and pH-responsive poly­(acrylic acid), respectively, by using surface-initiated atom transfer radical polymerization. The membrane clearly showed two independent on–off gates depending on temperature and pH. Furthermore, through light irradiation of two different wavelengths (near-infrared and ultraviolet), temperature and pH were also controlled independently and promptly. Thus, this membrane shows two independent on–off gating of the transport of a model biomolecule of fluorescein isothiocyanate-labeled bovine serum albumin. This strategy suggests the potential of independently modified membrane in layers as stimuli-responsive on–off gates for the application of artificial cell membrane

Additional file 2: of GScluster: network-weighted gene-set clustering analysis

Table S1, Table S2, and Table S3. Supplementary tables. Gene-set clustering results of the colon cancer, type II diabetes, and AML examples using three different distance measures. (XLSX 139 kb