Polymer Vesicles with Upper Critical Solution Temperature for Near-infrared Light-triggered Transdermal Delivery of Metformin in Diabetic Rats

Near-infrared light(NIR)triggered transdermal drug delivery systems are of great interest due to their on-demand drug release,which enable to enhance drug treatment efficiency as well as reduce side effect.Herein,a NIR-triggered microneedle(MN)patch array has been fabricated through depositing the photothermal conversion agent and anti-diabetic drug-loaded polymer vesicles with upper critical solution temperature(UCST)into dissolvable polymer matrix.The UCST-type polymer has a clearing point temperature of 41℃ and the drug-loaded polymer vesicles present excellent NIR-triggered and temperature responsive drug release behavior in vitro due to the disassociation of polymer vesicles upon NIR irradiation.After applying MNs to diabetic rats,significant hypoglycemic effect is achieved upon interval NIR irradiation and the blood glucose concentration can decrease to normal state for several hours,which enables to achieve the goal of on-demand drug release.This work suggests that the NIR-triggered MN drug release device has a potential application in the treatment of diabetes,especially for those requiring an active drug release manner.

Visualizing phase transition of upper critical solution temperature (UCST) polymers with AIE

The stimuli-responsive polymers with upper critical solution temperatures(UCST) are highly attractive for drug delivery applications. However, the phase transition process of UCST polymer is usually characterized by turbidity measurement and electron microscopy, which are significantly restricted by low sensitivity and static observation. In contrary, the fluorescence technique has significant advantages in terms of high sensitivity, easy operation, and dynamic observation. However, the conventional fluorophores suffer from the drawbacks of aggregation-caused quenching(ACQ) after being encapsulated by UCST polymers, which are not suitable for direct visualization of the phase transition process. To tackle this challenge, we herein developed a series of UCST polymers based on polyacrylamides decorated with bile acid and aggregation-induced emission(AIE)-active tetraphenylethene(TPE) groups, which can be used for direct fluorescence monitoring of the phase transition process. Moreover, the AIE-active UCST polymers can serve as drug carriers, which can not only monitor the drug release process under thermal stimuli, but also verify the drug release by fluorescence recovery after thermal stimuli. It is expected that the AIE-active UCST polymers with self-monitoring ability are promising for biomedical applications.

Multifunctional Gd-CuS loaded UCST polymeric micelles for MR/PA imaging-guided chemo-photothermal tumor treatment

Hepatocellular carcinoma(HCC)is a life-threatening disease for which there is no effective treatment currently.Novel theranostics simultaneously having excellent imaging and therapeutic functions are highly desired in cancer therapy.Herein,we develop the sialic acid(SA)modified polymeric micelles at an upper critical solution temperature(UCST)of 43℃(sialic acid-poly(ethylene glycol)-poly(acrylamide-co-acrylonitrile),SA-PEG-p(AAm-co-AN)),which further encapsulated with doxorubicin(DOX)and Gd-CuS nanoparticles(Gd-CuS NPs)for chemo-photothermal treatment of HCC guided by magnetic resonance(MR)/photoacoustic(PA)dual-mode imaging.The resultant SA-PEG-p(AAm-co-AN)/DOX/Gd-CuS(SPDG)had an excellent photothermal conversion efficiency,enabling SPDG with an instantaneous release behavior of DOX under near-infrared(NIR)irradiation.This study also revealed that SPDG could actively target to HCC,which was due to that SA had a high affinity with E-selectin overexpressed at the tumor site.Moreover,benefiting from the HCC-targeted ability and NIR light-controlled on-demand delivery of DOX,SPDG showed a superior potential in MR/PA dual-mode imaging-guided chemo-photothermal treatment.Overall,our study reveals that the designed SPDG may be used as an ideal multifunctional nanoplatform for cancer theranostics.