Acetylcholinesterase (AChE) is a significant enzyme, which plays critical roles in numerous physiological and pathological processes. Thus, selective, and sensitive real-time imaging of AChE activity in vivo has great importance...
Hydrogen sulfide (H2S) is one of the critical
gasotransmitters,
which play important roles in regular physiological processes, especially
in vital signaling pathways. However, fluctuations in endogenous H2S concentration can be linked to serious health problems,
such as neurodegenerative diseases, cancer, diabetes, inflammation,
cardiovascular diseases, and hypertension. Thus, it has attracted
a great deal of attention in therapeutic applications, specifically
in the field of phototherapy. Photodynamic therapy (PDT) and photothermal
therapy (PTT) are two subclasses of phototherapy, which utilize either
reactive oxygen species (ROS) or local temperature increase upon irradiation
of a photosensitizer (PS) to realize the therapeutic action. Phototherapies
offer unique advantages compared to conventional methods; thus, they
are highly promising and popular. One of the design principles followed
in new generation PSs is to build activity-based PSs, which stay inactive
before getting activated by disease-associated stimuli. These activatable
PSs dramatically improve the selectivity and efficacy of the therapy.
In this review, we summarize small molecule and nanomaterial-based
PDT and PTT agents that are activated selectively by H2S to initiate their cytotoxic effect. We incorporate single mode
PDT and PTT agents along with synergistic and/or multimodal photosensitizers
that can combine more than one therapeutic approach. Additionally,
H2S-responsive theranostic agents, which offer therapy
and imaging at the same time, are highlighted. Design approaches,
working principles, and biological applications for each example are
discussed in detail.
Hydrogen sulfide (H2S) as a critical messenger molecule plays vital roles in regular cell function. However, abnormal levels of H2S, especially mitochondrial H2S, is directly correlated with the formation of...
Photodynamic therapy (PDT) is a clinically approved treatment modality used for a wide range of medical conditions, including malignant cancers. It employs cytotoxic reactive oxygen species (ROS), particularly singlet oxygen (1O2), to kill cells of interest and has attracted immense attention during the last decades. Molecular design of triplet photosensitizers is no doubt at the core of successful PDT action. Spatiotemporal control of ROS generation and consequent cancer cell selectivity is one of the highly sought characteristics of new-generation photosensitizers, to minimize severe adverse effects as well as to enhance the therapeutic outcome. Activatable photosensitizers have appeared to be a good candidate in this respect as they tend to stay in their “off” state prior to activation with various tumor-associated intracellular stimuli. In this chapter, we summarize the recent advances in the field of activatable photosensitizers by focusing on the design principles and biologically relevant activators.
A resorufin-based dual-locked fluorescent probe (RHT) was introduced to image melanoma cells selectively. RHT was shown to function as an AND molecular logic gate as it emitted a signal only...
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