Due to their large anti-Stokes shifts, sharp emission spectra and long excited-state lifetimes, upconversion nanoparticles (UCNPs) have attracted an increasing amount of research interests, and have shown great potential for enhancing the practical utility of gene therapy, whose versatility has been limited by existing gene delivery technologies that are basically mono-functional in nature. Despite this, up to now in-depth analysis of the development of UCNPs for gene delivery has been scant in the literature, even though there has been an upsurge of reviews on the chemistry of UCNPs and their applications in bioimaging and drug delivery. To fill this gap, this review aims to present the latest advances in the development and applications of UCNPs as gene carriers. Prior to describing the prominent works published in the field, a critical view on the properties, chemistry and molecular design of UCNPs for gene delivery is provided. With a synopsis of the recent advances in UCNP-mediated gene delivery, challenges and opportunities could be illuminated for clinical translation of works in this nascent field of research.

Due to their large anti-Stokes shifts, sharp emission spectra and long excited-state lifetimes, upconversion nanoparticles (UCNPs) have attracted an increasing amount of research interests, and have shown great potential for enhancing the practical utility of gene therapy, whose versatility has been limited by existing gene delivery technologies that are basically mono-functional in nature. Despite this, up to now in-depth analysis of the development of UCNPs for gene delivery has been scant in the literature, even though there has been an upsurge of reviews on the chemistry of UCNPs and their applications in bioimaging and drug delivery. To fill this gap, this review aims to present the latest advances in the development and applications of UCNPs as gene carriers. Prior to describing the prominent works published in the field, a critical view on the properties, chemistry and molecular design of UCNPs for gene delivery is provided. With a synopsis of the recent advances in UCNP-mediated gene delivery, challenges and opportunities could be illuminated for clinical translation of works in this nascent field of research.

Cyclodextrins (CDs) are naturally occurring cyclic oligosaccharides bearing a basket-shaped topology with an “inner–outer” amphiphilic character. The abundance of hydroxyl groups enables CDs to be functionalized with multiple targeting ligands and imaging elements. The imaging time, and the payload of different imaging elements, can be tuned by taking advantage of the commercial availability of CDs with different sizes of the cavity. This review aims to offer an outlook of the chemistry and engineering of CDs for the development of molecular probes. Complexation thermodynamics of CDs, and the corresponding implications for probe design, are also presented with examples demonstrating the structural and physiochemical roles played by CDs in the full ambit of molecular imaging. We hope that this review not only offers a synopsis of the current development of CD-based molecular probes, but can also facilitate translation of the incremental advancements from the laboratory to real biomedical applications by illuminating opportunities and challenges for future research.

Cyclodextrins (CDs) are naturally occurring cyclic oligosaccharides bearing a basket-shaped topology with an “inner–outer” amphiphilic character. The abundance of hydroxyl groups enables CDs to be functionalized with multiple targeting ligands and imaging elements. The imaging time, and the payload of different imaging elements, can be tuned by taking advantage of the commercial availability of CDs with different sizes of the cavity. This review aims to offer an outlook of the chemistry and engineering of CDs for the development of molecular probes. Complexation thermodynamics of CDs, and the corresponding implications for probe design, are also presented with examples demonstrating the structural and physiochemical roles played by CDs in the full ambit of molecular imaging. We hope that this review not only offers a synopsis of the current development of CD-based molecular probes, but can also facilitate translation of the incremental advancements from the laboratory to real biomedical applications by illuminating opportunities and challenges for future research.

Incorporating hydrogel particles with the core–shell architecture is a promising route to fabricate colloidal “smart gels” with tuneable properties. This study reports a facile electrospray-based method to generate compositionally homogeneous core–shell hydrogel microspheres. By manipulating different process parameters (e.g., electric field strength, flow rate, and gel-forming polymer concentration), the size of the microspheres can be tuned from microns to millimetres. Drug release studies demonstrate that coating the surface of the hydrogel microsphere with a hydrogel layer remarkably prolongs the drug release sustainability. In 3T3 and HEK293 cells, both the acute and delayed toxicity caused by the hydrogel microspheres are shown to be negligible. Together with the ease of operation of the production method, the compositionally homogeneous core–shell microspheres generated by our method may enhance the versatility and flexibility in future drug delivery.

Incorporating hydrogel particles with the core–shell architecture is a promising route to fabricate colloidal “smart gels” with tuneable properties. This study reports a facile electrospray-based method to generate compositionally homogeneous core–shell hydrogel microspheres. By manipulating different process parameters (e.g., electric field strength, flow rate, and gel-forming polymer concentration), the size of the microspheres can be tuned from microns to millimetres. Drug release studies demonstrate that coating the surface of the hydrogel microsphere with a hydrogel layer remarkably prolongs the drug release sustainability. In 3T3 and HEK293 cells, both the acute and delayed toxicity caused by the hydrogel microspheres are shown to be negligible. Together with the ease of operation of the production method, the compositionally homogeneous core–shell microspheres generated by our method may enhance the versatility and flexibility in future drug delivery.

Sensitization of lanthanide luminescence in the visible and near infra-red (NIR) region was achieved via a non-triplet energy transfer pathway by long-wavelength excitation of an intraligand charge transfer (ILCT) band of a diethylamino-based ligand system. A comprehensive photophysical and solvatochromic study is conducted to evaluate the luminescence properties of our Eu(III), Sm(III) and Yb(III) complexes. The effects of solvent coordination and solvent quenching on lanthanide luminescence were studied in detail and efforts were also devoted into examining the ambiguous energy transfer mechanism of Yb(III) sensitization.