Confocal microscopy images of core-shell microgels MS1 in Hela cells (a–c, human cervical cancer) or J774A.1 cells (d–f, Mouse macrophage).

<p>(a) and (d) Green fluorescence of core-shell microgels inside cells. (b) and (e) Bright field images of cells. (c) and (d) Overlay images of (a)/(b) and (d)/(e). Green fluorescence was excited at 440 nm and emissions were collected using a 515/30 nm filter set. Scale bars represent 20 µm.</p

Response of the core-shell microgels (MS2) to pH in PBS buffer.

<p>(a) Typical fluorescence intensity change at different pH values in PBS buffer. (b–c) Boltzmann fittings, which were performed using eq 2 with/without ratiometric calibration. (d) Change in fluorescence intensity ratio (F₅₀₀/F₆₆₅) of MS2 in PBS buffer, where the pH was changed repeatedly between 3 and 11.</p

Dually Fluorescent Core-Shell Microgels for Ratiometric Imaging in Live Antigen-Presenting Cells

<div><p>Core-shell microgels containing sensors/dyes in a matrix were fabricated by two-stage free radical precipitation polymerization method for ratiometric sensing/imaging. The microgels composing of poly(<i>N</i>-isopropylacrylamide) (PNIPAm) shell exhibits a low critical solution temperature (LCST), underwent an entropically driven transition from a swollen state to a deswollen state, which exhibit a hydrodynamic radius of ∼450 nm at 25°C (in vitro) and ∼190 nm at 37°C (<i>in vivo</i>). The microgel’s ability of escaping from lysosome into cytosol makes the microgel be a potential candidate for cytosolic delivery of sensors/probes. Non-invasive imaging/sensing in Antigen-presenting cells (APCs) was feasible by monitoring the changes of fluorescence intensity ratios. Thus, these biocompatible microgels-based imaging/sensing agents may be expected to expand current molecular imaging/sensing techniques into methods applicable to studies in vivo, which could further drive APC-based treatments.</p></div

Schematic illustration of the preparation process of the P(St-<i>co</i>-NIPAm)-PNIPAm core-shell microgels.

<p>Schematic illustration of the preparation process of the P(St-<i>co</i>-NIPAm)-PNIPAm core-shell microgels.</p

Response of the core-shell microgels (MS1) to dissolved oxygen in PBS buffer.

<p>(a) Typical response to dissolved oxygen in PBS pH 7.4 buffer. (b–c) Fits of the Stern-Volmer plots, whichwere performed using eq 1 with/without ratiometric calibration. (d) Change in fluorescence intensity ratio (F₅₂₅/F₆₅₀) of MS1 in PBS buffer, where the oxygen concentration was changed repeatedly between 0 and 12 ppm.</p

Confocal microscopy images of core-shell microgels MS1 in J774A.1 cells co-stained with nucleic staining Hoechst 33342 (a–c) and LysoTracker Red® (d–f).

<p>(a) Hoechst 33342 blue fluorescence inside cells. (b) and (e) Green fluorescence of core-shell microgels inside cells. (d) LysoTracker Red® red fluorescence inside cells. (c) Overlay images of (a) and (b). (f) Overlay images of (d) and (e). Hoechst 33342 was excited at 402 nm and its blue emission was collected using a 450/35 nm filter set; green fluorescence was excited at 440 nm and emissions were collected using a 515/30 nm filter set; LysoTracker Red® fluorescence was excited at 561 nm and its red emission was collected using a 605/75 nm filter set. Scale bars represent 20 µm.</p

Cytotoxicity of the microgels MS1 to J774A.1 (blue) and Hela (red) cells after incubation at 37

<p>°<b>C for 24 h.</b> The concentration of “control” in the x-axis means the control cells without adding any of the microgels<b>.</b></p

Size and distribution of the core (OS1 in PSt) and the core-shell microgels (MS1) prepared by microemulsion polymerization determined by TEM (a, b) and DLS (c).

<p>Size and distribution of the core (OS1 in PSt) and the core-shell microgels (MS1) prepared by microemulsion polymerization determined by TEM (a, b) and DLS (c).</p

Confocal microscopy images of J774A.1 cells treated with core-shell microgel MS1.

<p>(a) Naphthalimide green fluorescence of core-shell microgels inside cells. (b) Porphyrin red fluorescence of core-shell microgels inside cells. (c) Overlay images of (a) and (b). Green fluorescence was excited at 440 nm and emissions were collected using a 515/30 nm filter set; Red fluorescence was excited at 440 nm and its red emission was collected using a 605/75 nm filter set. Scale bars represent 20 µm.</p

Photophysical properties of PtTFPP in micelles, THF and CH₂Cl₂ solutions.

<p>Photophysical properties of PtTFPP in micelles, THF and CH₂Cl₂ solutions.</p