Fluorescent micro- and nanosized particles have a broad range of applications in biology, medicine, and engineering. For these uses, the materials should have high emission efficiency and good photostability. However, many organic fluorophores suffer from aggregation-induced quenching effects and photobleaching. Here, we used a simple method based on covalently blending a fluorescent conjugated oligomer with silica nanoparticles to achieve emission quantum yields as high as 97%. The resulting system also showed excellent stability under continuous light illumination, in a range of pH values and temperatures, and in common solvents. This fluorescent material showed outstanding properties, including highly efficient blue emission, low cost, low toxicity, and easy synthesis. Furthermore, its effectiveness for latent fingerprint detection was demonstrated as a proof of concept on various substrates. The obtained emissive fingerprint powder gave good optical/fluorescent images with high contrast and resolution between the ridges and spaces.

Photochromic diarylethene derivatives, which can reversibly switch the fluorescence of adjacent fluorophores between the ON and OFF states under light irradiation, have been widely used to construct photoswitchable materials. Herein, eight dithienylethene (DTE) groups are integrated onto one polyhedral oligomeric silsesquioxane (POSS) core, obtaining a novel super molecular photoswitch. After being doped into conjugated polymer nanoparticles, the POSS-DTE molecules show a higher contrast on/off photoswitching performance and a quicker responsive speed than free DTE molecules at same molar concentration of photochromic units. This enhanced photoswitching efficiency is attributed to the increased molecular interaction of the ring-open form and lowered energy of the ring-closed form of the DTE units on the POSS core, which is beneficial for the ring-closing reaction and subsequent energy transfer between photoswitch and fluorophores. In addition, POSS-DTE also exhibits good photomodulation behavior in the conjugated polymer film, giving it potential applications in optical devices.

No abstract

No abstract

Photodynamic therapy (PDT) has been recognized as one powerful solution to treat cancers, but its efficacy is often impaired by the oxygen‐deficient hypoxic tumor microenvironment. Herein, conjugated oligomer‐based hollow nanoparticles are developed as efficient phototheranostic agent for targeted PDT under hypoxia. The sialic acid (SA)‐imprinted hollow nanoparticles are facilely prepared via a nanoprecipitation method using a conjugated oligomer as photosensitizer and an amphiphilic polymer as matrix. The strong intra‐ and inter‐molecular π–π stacking interactions of the conjugated oligomer direct the self‐assembly and formation of hollow nanostructure. Triggered by 660 nm laser, the nanoparticles exhibit prominent reactive oxygen species (ROS) generation both in water and cellular medium, which are specifically determined as singlet oxygen (1O2) and superoxide radical (O2–•) under normoxia (20% O2) while mainly O2–• under hypoxia (1% O2). Moreover, the feature of SA‐imprinted surface makes these nanoparticles capable of selectively targeting and being internalized into SA over‐expressed cancer cells, and their efficient PDT behaviors in vitro are also demonstrated even under severely hypoxic environment. Thus, the work provides a promising photosensitizer candidate for targeted PDT in hypoxic tumor.