Fluorescent semiconducting polymer dots (Pdots) have attracted great interest because of their superior characteristics as fluorescent probes, such as high fluorescence brightness, fast radiative rates, and excellent photostability. However, currently available Pdots generally exhibit broad emission spectra, which significantly limit their usefulness in many biological applications involving multiplex detections. Here, we describe the design and development of multicolor narrow emissive Pdots based on different boron-dipyrromethene (BODIPY) units. BODIPY-containing semiconducting polymers emitting at multiple wavelengths were synthesized and used as precursors for preparing the Pdots, where intra-particle energy transfer led to highly bright, narrow emissions. The emission full-width at half maximum (FWHM) of the resulting Pdots varies from 40 nm to 55 nm, which is 1.5~2 times narrower than those of conventional semiconducting polymer dots. BODIPY520 Pdots was about an order of magnitude brighter than commercial Qdot 525 under identical laser excitation conditions. Fluorescence imaging and flow cytometry experiments indicate the narrow emissions from these bright Pdots are promising for multiplexed biological detections.

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A facile cross‐linking strategy covalently links functional molecules to semiconducting polymer dots (Pdots) while simultaneously providing functional groups for biomolecular conjugation. In addition to greatly enhanced stability, the formed Pdots are small (<10 nm), which can be difficult to achieve with current methods but is highly desirable for most biological applications. These characteristics are significant for improving labeling efficiency and sensitivity in cellular assays that employ Pdots.

This article describes the design and development of squaraine-based semiconducting polymer dots (Pdots) that show large Stokes shifts and narrow-band emissions in the near-infrared (NIR) region. Fluorescent copolymers containing fluorene and squaraine units were synthesized and used as precursors for preparing the Pdots, where exciton diffusion and likely through-bond energy transfer led to highly bright and narrow-band NIR emissions. The resulting Pdots exhibit the emission full width at half-maximum of ∼36 nm, which is ∼2 times narrower than those of inorganic quantum dots in the same wavelength region (∼66 nm for Qdot705). The squaraine-based Pdots show a high fluorescence quantum yield (QY) of 0.30 and a large Stokes shift of ∼340 nm. Single-particle analysis indicates that the average per-particle brightness of the Pdots is ∼6 times higher than that of Qdot705. We demonstrate bioconjugation of the squaraine Pdots and employ the Pdot bioconjugates in flow cytometry and cellular imaging applications. Our results suggest that the narrow bandwidth, high QY, and large Stokes shift are promising for multiplexed biological detections.

We demonstrate a new compact CN-PPV dot, which emits in the orange wavelength range with high brightness. The small particle size, high brightness, and the ability to highly specifically target subcellular structures make the CN-PPV dots promising probes for biological imaging and bioanalytical applications.

Compared with conventional tumor photothermal therapy (PTT), mildtemperature PTT brings less damage to normal tissues, but also tumor thermoresistance, introduced by the overexpressed heat shock protein (HSP). A high dose of HSP inhibitor during mild-temperature PTT might lead to toxic side effects. Glucose oxidase (GOx) consumes glucose, leading to adenosine triphosphate supply restriction and consequent HSP inhibition. Therefore, a combinational use of an HSP inhibitor and GOx not only enhances mildtemperature PTT but also minimizes the toxicity of the inhibitor. However, a GOx and HSP inhibitor-encapsulating nanostructure, designed for enhancing its mild-temperature tumor PTT efficiency, has not been reported. Thermosensitive GOx/indocyanine green/gambogic acid (GA) liposomes (GOIGLs) are reported to enhance the efficiency of mild-temperature PTT of tumors via synergistic inhibition of tumor HSP by the released GA and GOx, together with another enzyme-enhanced phototherapy effect. In vitro and in vivo results indicate that this strategy of tumor starvation and phototherapy significantly enhances mild-temperature tumor PTT efficiency. This strategy could inspire people to design more delicate platforms combining mildtemperature PTT with other therapeutic methods for more efficient cancer treatment.

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