ABSTRACT
After more than five decades, Moore's Law for transistors is approaching the end of the international technology roadmap of semiconductors (ITRS). The fate of complementary metal oxide semiconductor (CMOS) architecture has become increasingly unknown. In this era, 3D transistors in the form of gate-all-around (GAA) transistors are being considered as an excellent solution to scaling down beyond the 5 nm technology node, which solves the difficulties of carrier transport in the channel region which are mainly rooted in short channel effects (SCEs). In parallel to Moore, during the last two decades, transistors with a fully depleted SOI (FDSOI) design have also been processed for low-power electronics. Among all the possible designs, there are also tunneling field-effect transistors (TFETs), which offer very low power consumption and decent electrical characteristics. This review article presents new transistor designs, along with the integration of electronics and photonics, simulation methods, and continuation of CMOS process technology to the 5 nm technology node and beyond. The content highlights the innovative methods, challenges, and difficulties in device processing and design, as well as how to apply suitable metrology techniques as a tool to find out the imperfections and lattice distortions, strain status, and composition in the device structures.
ABSTRACT
Two-photon excitation (2PE) photodynamic therapy (PDT) is a non-invasive technique for the treatment of cancer. However, its clinical applications are limited by small two-photon absorption cross section values of conventional photosensitizers. Here we designed multifunctional conjugated polymer based nanoparticles consisting of a conjugated polymer, a photosensitizer and a red-emitting dye, which can realize simultaneous 2PE red emission imaging and 2PE-PDT activities. The working principle is based on a 2PE fluorescence resonance energy transfer strategy from the conjugated polymer to photosensitizing and imaging agents. In these nanoparticles (NPs), the conjugated polymer, PPBF, was chosen as a two-photon light-harvesting material while the photosensitizer (tetraphenylporphyrin, TPP) and the red-emitting dye (TPD) were chosen as energy acceptors. The 2PE emission of TPP and TPD was enhanced by up to â¼161 and â¼23 times, respectively. The 2PE-PDT activity of these NPs was significantly improved compared with those NPs without PPBF by up to â¼149 times. Further surface-functionalization with folic acid (FA) groups allows these nanoparticles to exhibit selective affinity toward KB cancer cells. These NPs could act as novel 2PE conjugated polymer based nanoparticles combined with the advantages of low dark cytotoxicity, selective targeting and imaging-guided 2PE-PDT activities.
Subject(s)
Nanoparticles/chemistry , Neoplasms/therapy , Photochemotherapy , Photosensitizing Agents/chemistry , Polymers/chemistry , Animals , Cell Line, Tumor , Cell Survival , Coloring Agents/chemistry , Fluorescence Resonance Energy Transfer , Humans , Lysosomes/chemistry , Mice , Microscopy, Electron, Transmission , Microscopy, Fluorescence , NIH 3T3 Cells , Photons , Porphyrins/chemistry , Reactive Oxygen Species/metabolism , Singlet Oxygen/chemistryABSTRACT
Using light as the sole stimulus and employing the generated singlet oxygen as a therapeutic agent and the trigger to activate chemo-drug release could serve as an elegant way to bring into full play the advantageous features of light and enhance therapeutic efficacy through a combination of chemotherapy and photodynamic therapy. Herein a liposomal drug system has been developed by embedding a fluorescent photosensitizer and a prodrug into phospholipid vesicles. Upon one- or two-photon light irradiation, the photosensitizer generates singlet oxygen, which removes the protecting group of the prodrug and subsequently causes the release of the active drug chlorambucil. With the combined action of O21 and chlorambucil, highly controllable cytotoxicity toward cancer cells was achieved. In addition, the fluorescent photosensitizer gives out fluorescent signal acting as the drug monitoring agent. This strategy may provide an efficient approach for cancer treatment and some useful insights for designing light-stimulated on-demand therapeutic systems.
