Fluorescent Supramolecular Polymersomes Based on Pillararene/Paraquat Molecular Recognition for pH-controlled Drug Release

Researchers have put significant efforts on developing versatile fluorescent polymeric systems due to their promising biological/biomedical labelling, tracking, monitoring, imaging, and diagnostic applications. However, complicated organic/polymeric synthesis or post-modification of these functionalized platforms is still a big obstacle for their further application and thereby provides clear motivation for exploring alternative strategies for the design and fabrication of easily available fluorescent systems. The marriage of supramolecular polymers and fluorescent imaging can provide a facile and dynamic manner instead of tedious and time-consuming synthesis due to the dynamic and reversible nature of noncovalent interactions. Herein, based on water-soluble pillararene/paraquat molecular recognition, we successfully prepare two amphiphilic polypseudorotaxanes which can self-assemble into supramolecular polymersomes in water. These polymersomes can be reversibly destroyed and reformed by tuning the solution p H. Attributed to the aggregation-induced emission of tetraphenylethylene groups,intense fluorescence can be introduced into the obtained supramolecular polymersomes. Furthermore, p H-triggered release of an encapsulated water-insoluble drug(doxorubicin) from the self-assembled fluorescent supramolecular polymersomes is also investigated.

Fluorescent polymer-modified gold nanobipyramids for temperature sensing during photothermal therapy in living cells

The temperature monitoring of treated cancer cells is critical in photothermal therapy.Current methods of detecting intracellular temperatures have low accuracy and poor spatial resolution,which limits their application to photothermal therapy.Herein,a strategy for targeted recognition and selective capture of MCF-7 breast cancer cells based on fluorescent polymer poly(N-isopropylacrylamide-benzoxadiazole-2-vinyl-4,4-dimethyl azlactone,PNMV)and modified gold nanobipyramids(Au NBPs-PNMV)was developed for temperature sensing during photothermal therapy.A mucin-1 protein aptamer(Apt)was applied to selectively target mucin-1 protein overexpressed on the surfaces of the MCF-7 cells,which can reduce interference by affinity interaction between the Apt and proteins.During photothermal therapy,the significant Au NBPs photothermal effect increases the fluorescence intensity of PNMV with temperature.Irradiation of MCF-7 cells cultured with Au NBPs-PNMV@Apt by an 808 nm laser increases the temperature of the system,while the cells can be inactivated because of the remarkable Au NBPs-PNMV@Apt photothermal effect.The results indicate that variation in the fluorescence of Au NBPs-PNMV@Apt can be applied as thermometers to monitor the intracellular effect of photothermal therapy.

Color-tunable and bright nonconjugated fluorescent polymer dots and fast photodegradation of dyes under visible light

Nonconjugated polymer dots(PDs)without largely conjugated structures entitle their advantages such as environment friendliness,nontoxicity,and intrinsic fluorescence.However,color-tunable PDs remain a challenge.Herein,polyvinyl pyrrolidone(PVP)and ascorbic acid(AA)are used to synthesize nonconjugated PDs,namely,PA PDs with intensive blue emission.The introduction of a third component,m-phenylenediamine(MPD),redshifted the emission to green.The asprepared color-tunable blue to green emissive PDs exhibit excellent properties,whether in solution or in solid state,originated from the mechanism of clusteringtriggered emission(CTE)induced by the overlap of electron-rich atoms,the strong inter/intrachain interaction.The quantum yields of blue and green PDs reached up to 15.07%and 28.22%,respectively.Furthermore,PA PDs were successfully applied to the highly efficient photocatalytic degradation for dyes:methylene blue(MB)and methyl orange(MO)were degraded by 89.9%and 93.8%within 20 min under visible light,respectively.

Aggregation-induced emission polymer systems with circularly polarized luminescence

Functional materials with circularly polarized luminescence(CPL)have attracted tremendous attention due to their promising applications in three-dimensional dis-plays,chiral recognition and catalysis,photoelectronic devices,contrast imaging,information encryption,and otherfields.Among various CPL-active materials,poly-meric systems with aggregation-induced emission(AIE)have emerged as excellent candidates because of their efficient aggregate-statefluorescence,large solid-state dissymmetry factor,excellent processibility,diversified self-assembly behaviors,and readily switchable CPL properties.This review summarizes and discusses the recent progress as well as future perspective of diverse AIE polymer systems with CPL,including CPL-active covalent AIE polymers,CPL-active supramolecular AIE polymers,and AIEgen/polymer composites with CPL.According to the loca-tion or introduction method of AIEgen in polymer structures,this review further divides CPL-active covalent AIE polymers into three categories,including polymers with AIEgen in main chains,polymers with AIEgen in side chains,and CPL-active polymers with clusterization-triggered emission.CPL-active supramolecular AIE polymers are discussed based on the driving force for the formation of supramolecular polymers,including host–guest interactions,metal coordination,and other non-covalent interactions.Moreover,examples on the construction of CPL-active AIEgen/polymer composites by physically mixing AIEgens with chi-ral(supra)polymers are also presented.This review is anticipated to provide readers with an overall view on the design strategies of CPL-active AIE polymers,and facil-itate further research on the development of CPL materials and AIE polymers with advanced applications.

Highly photostable nanogels for fluorescence-based theranostics

A novel photo-crosslinkable nanogel is prepared from a biodegradable polymer template with intrinsic photoluminescence and high photostability.The fluorescent nanogels display excellent biodegradability and cytocompatibility owed to the facile synthesis scheme involving a solvent-and surfactant-free onepot reaction,derived entirely from biocompatible monomers citric acid,maleic acid,L-cysteine,and poly(ethylene glycol).The resultant nanogels are less than 200 nm in diameter with a narrow size distribution and monodispersity,and demonstrate long-term structural stability in biological buffer for two weeks.To gauge potential in theranostic applications,the fluorescent nanogels were surface functionalized with biologically active RGD peptides and encapsulated with active anti-cancer drug Doxorubicin,resulting in a pH-responsive controlled drug release in acidic pH resembling tumor environments.The strong fluorescence of the nanogels enabled tracking of targeted drug delivery,showing that drug-loaded nanogels homed into the cytoplasmic regions of prostate cancer cells to significantly induce cell death.These photo-crosslinkable and biodegradable nanogels pose as a strong candidate for theranostic medicine,demonstrating versatile functionalization,high stability in biological buffers,and capacity for real-time fluorescence-based monitoring of targeted drug delivery.