This review presents a robust strategy to design photosensitizers (PSs) for various species. Photodynamic therapy (PDT) is a photochemical-based treatment approach that involves the use of light combined with a light-activated chemical, referred to as a PS. Attractively, PDT is one of the alternatives to conventional cancer treatment due to its noninvasive nature, high cure rates, and low side effects. PSs play an important factor in photoinduced reactive oxygen species (ROS) generation. Although the concept of photosensitizer-based photodynamic therapy has been widely adopted for clinical trials and bioimaging, until now, to our surprise, there has been no relevant review article on rational designs of organic PSs for PDT. Furthermore, most of published review articles in PDT focused on nanomaterials and nanotechnology based on traditional PSs. Therefore, this review aimed at reporting recent strategies to develop innovative organic photosensitizers for enhanced photodynamic therapy, with each example described in detail instead of providing only a general overview, as is typically done in previous reviews of PDT, to provide intuitive, vivid, and specific insights to the readers.

Owing to its spatiotemporal selectivity and noninvasive nature, photodynamic therapy (PDT) has become a clinically promising approach for the treatment of a wide range of cancers and other diseases. However, the full potential of PDT has not been achieved thus far as a consequence of the lack of optimal photosensitizers (PSs) and/or smart transport/activation strategies. These problems, which unfortunately lie at the core of the PDT paradigm, include the oxygen reliance limits, the effect of PDT on hypoxic tumors, limitations of light penetration, and undesired skin photosensitization induced by "always on" PSs. Recently, supramolecular approaches, which rely on the use of non-covalent interactions to construct biomedical active materials, have become suitable methods for developing innovative PSs. Non-covalent interactions enable supramolecular PSs to have sensitive and controllable photoactivities, important elements needed to maximize photodynamic effects and minimize side effects. In addition, versatile supramolecular PS-assemblies can be designed so that PDT occurs synergistically with other therapeutic modalities, e.g., photothermal therapy, leading to a potential improvement of therapeutic effectiveness. In this review, recent progress made in the development of supramolecular PSs for rejuvenating PDT will be presented. Importantly, this discussion also provides a view of future advances that will likely be made in this area and their potential clinical applications.

Introduction 7944 2. Chemosensors Based on Fluorescent Molecules 7945 2.1. Sensors for Environment Exhaust Gases 7945 2.1.1. Sensors for CO 2 7945 2.1.2. Sensors for SO 2 7949 2.1.3. Sensors for O 3 7951 2.2. Sensors for Biological Signaling Gases 7952 2.2.1. Sensors for NO 7952 2.2.2. Sensors for CO 7957 2.2.3. Sensors for H 2 S 7958 2.2.4. Sensors for 1 O 2 7962 2.3. Sensors for Highly Toxic Chemical-Warfare Agents 7963 2.3.1. Sensors for Nerve Agents 7963 2.3.2. Sensors for Sulfur Mustard 7967 3. Sensors Based on Functional Materials 7968 3.1. Sensors for Environment Gases 7968 3.1.1. Sensors for CO 2 7968 3.1.2. Sensors for O 2 7969 3.1.3. Sensors for VOCs 7971 3.1.4. Sensors for HCl 7972 3.1.5. Sensors for NH 3 7972 3.1.6. Sensors for Other Gases 7974 3.2. Sensors for High Dangerous Gases 7976 3.2.1. Sensors for Nerve Agents 7976 3.2.2. Sensors for Explosives 7976 4. Chemosensors Based on Metal Oxide Semiconductor 7978 4.1. Sensors for Environmental Gases 7978 4.1.1. Sensors for VOCs 7978 4.1.2. Sensors for CO 2 7985 4.1.3. Sensors for NO 2 7985 4.1.4. Sensors for SO 2 7987 4.1.5. Sensors for Other Gases 4.2. Sensors for Highly Toxic Gases 4.2.1. Sensors for CO 4.2.2. Sensors for H 2 S 4.2.3. Sensors for O 3 5. Conclusions and Future Perspectives Author Information

Highlights College students’ experiences of emergency remote teaching due to COVID19. Results revealed advantages, disadvantages, and desired improvements. The need for further development for a successful learning experience is demonstrated. Specific suggestions for such developments are provided.

Pyrophosphate anions play key roles in various biological and chemical processes. During the last few years, many exciting results have emerged regarding the development of fluorescent and colorimetric sensors for this biologically important species. In this review, we will cover the fluorescent and colorimetric chemosensors developed for the detection of pyrophosphate (PPi) since 2010.