Drug-delivery and multifunction possibilities of hypocrellin photosensitizers

Photodynamic therapy(PDT)has been a routine treatment of tumors and some microvascular diseases,but clinically available photosensitizers are still scarce.Among all kinds of photo-sensitizers,hypocellins possess the most characteristics of ideal photosensitizers,such as,high photo-activity but low dark toxicity,fast clearance from tssues.This review is focused on two main topics,drug-delivery problem of hypocrellins and how the environment-sensitive fluorescence of bypecrellins was used for recognition of various biomolecules.Drug-delivery of hypocrellins was mainly achieved in two strategies一preparing the drugdelivery vehicles and finding quantitatively amphiphilic derivatives.Hypocrellin fAuorescence originated from the intramolecular proton transfer is very distinct from other kinds of photosensitizers.Recently,it was proved that quan-titative hypocrellin ftuorescence could not only reoognize various biomolecules,including proteins,polysaocharides and lipids,but also distinguish the specific binding from nonspedifie binding with some kind of biomolecules.Meantime,hypocrellin fluorescence was pH sensitive.It is known that tumor cells or tses have the features of a large amount of lipid,neonatal collagen,over expression of polysaccharides,and lower pH values compared to normal tissues.According to the relative but not absolute specifcity,further studies on quantitative recognition of various biomolecules at a cellular level,may find a new clue to treat tumors by joint usage of photodynamic diagnosis(PDD)and PDT.

Aptamers as Recognition Elements for Electrochemical Detection of Exosomes

Exosome analysis is emerging as an attractive noninvasive approach for disease diagnosis and treatment monitoring in the field of liquid biopsy.Aptamer is considered as a promising molecular probe for exosomes detection because of the high binding affinity,remarkable specificity,and low cost.Recently,many approaches have been developed to further improve the performance of electrochemical aptamer based(E-AB)sensors with a lower limit of detection.In this review,we focus on the development of using aptamer as a specific recognition element for exosomes detection in electrochemical sensors.We first introduce recent advances in evolving aptamers against exosomes.Then,we review methods of immobilization aptamers on electrode surfaces,followed by a summary of the main strategies of signal amplification.Finally,we present the insights of the challenges and future directions of E-AB sensors for exosomes analysis.

Recent Progress on Highly Selective and Sensitive Electrochemical Aptamer-based Sensors

Highly selective,sensitive,and stable biosensors are essential for the molecular level understanding of many physiological activities and diseases.Electrochemical aptamer-based(E-AB)sensor is an appealing platform for measurement in biological system,attributing to the combined advantages of high selectivity of the aptamer and high sensitivity of electrochemical analysis.This review summarizes the latest development of E-AB sensors,focuses on the modification strategies used in the fabrication of sensors and the sensing strategies for analytes of different sizes in biological system,and then looks forward to the challenges and prospects of the future development of electrochemical aptamerbased sensors.