Dual-emitting fluorescence ratiometric nanoprobes of in-vitro/in-vivo pH from constructions to sensing, imaging and therapeutic applications

During the past two decades, there is an explosive growth of numerous scientific researches on dual-emitting fluorescence ratiometric nanoprobes (FRNPs). FRNPs adopt dual-signal ratiometry as signal output toward specific targets, and exhibit unique in-built signal self-calibration function and high accuracy for target detection. Especially, FRNPs can perform high-performance detection of in-vitro/in-vivo pH. These explored FRNPs-pH systems were extensively applied to pH-sensing, imaging and therapeutic applications at the levels of living cells and small animals. Thereby, this review has systematically summarized the promising FRNPs-pH systems reported in recent years. The first section has clearly introduced dual-emission fluorescence (FL) ratiometric modes and FL sensing mechanisms during the construction and application processes. The second section wholly summarizes various construction methods of FRNPs-pH systems based on different compositions and structures. The third section rationally discusses potential applications of FRNPs-pH systems, referring to FL bioimaging at the levels of living cells and small animals, pH-sensing and imaging detection at the levels of whole cells, organelles, tissues and organs, as well as FL imaging-guided tumor therapy. Furthermore, the current status, potential challenges and development perspectives in following researches are analyzed reasonably. This comprehensive and timely review promotes further explorations of multifunctional luminescent nanoprobes and versatile sensing materials for highly efficient biomedical applications.