Bingbing Sun

Multilayer Microcapsules for FRET Analysis and Two-Photon-Activated Photodynamic Therapy.

Microcapsules obtained by layer-by-layer assembly provide a good platform for biological analysis owing to their component diversity, multiple binding sites, and controllable wall thickness. Herein, different assembly species were obtained from two-photon dyes and traditional photosensitizers, and further assembled into microcapsules. Fluorescence resonance energy transfer (FRET) was shown to occur between the two-photon dyes and photosensitizers. Confocal laser scanning microscopy (CLSM) with one- and two-photon lasers, fluorescence lifetime imaging microscopy (FLIM), and time-resolved fluorescence spectroscopy were used to analyze the FRET effects in the microcapsules. The FRET efficiency could easily be controlled through changing the assembly sequence. Furthermore, the capsules are phototoxic upon one- or two-photon excitation. These materials are thus expected to be applicable in two-photon-activated photodynamic therapy for deep-tissue treatment.

Bis(pyrene) Doped Cationic Dipeptide Nanoparticles for Two-Photon-Activated Photodynamic Therapy

At present, one of main problems for photodynamic therapy (PDT) is how to improve the treatment depth. Two-photon activated (TPA) developed recently provide a possible solution for it. In this work, we report the energy-transferring assembled cationic dipeptide nanoparticles for two-photon activated photodynamic therapy (TPA-PDT). In the nanoparticles, the coencapsulated two-photon fluorescent dye bis(pyrene) (BP) is an energy donor, and a photosensitizer rose bengal (RB) is an acceptor based on an intraparticle fluorescence resonance energy transfer (FRET) mechanism. BP in the nanoparticles can be excited by one- or two- photon laser. And then, the energy of BP was transferred to RB, which highly enhanced the generation of singlet oxygen. The cellular experiments indicated that this nanosystem can induce the cytotoxicity under one- and two-photon irradiation, which allows further applications of FRET-based biomaterials for TPA-PDT.

Disassembly of Dipeptide Single Crystals Can Transform the Lipid Membrane into a Network

Coupling between cytoskeleton and membranes is critical to cell movement as well as organelle formation. Here, we demonstrate that self-assembled single crystals of a dipeptide, diphenylalanine (FF), can interact with liposomes to form cytoskeleton-like structures. Under a physiological condition, disassembly of FF crystals deforms and translocates supported lipid membrane. The system exhibits similar dynamic characteristics to the endoplasmic reticulum (ER) network in cells. This bottom-up system thus indicates that external matter can participate in the deformation of liposomes, and disassembly of the nanostructures enables a system with distinct dynamic behaviors.

Self-Assembly of Ultralong Aligned Dipeptide Single Crystals

Oriented arrangement of single crystals plays a key role in improving the performance of their functional devices. Herein we describe a method for the exceptionally fast fabrication (mm/min) of ultralong aligned dipeptide single crystals (several centimeters). It combines an induced nucleation step with a continuous withdrawal of substrate, leading to specific evaporation/composition conditions at a three-phase contact line, which makes the growth process controllable. These aligned dipeptide fibers possess a uniform cross section with active optical waveguiding properties that can be used as waveguiding materials. The approach provides guidance for the controlled arrangement of organic single crystals, a family of materials with considerable potential applications in large-scale functional devices.

Automatic Assembly of Ultra-Multilayered Nanotube-Nanoparticle Composites.

Nanotube-nanoparticle composites are fabricated by template-directed automatic layer-by-layer assembly with the assistance of pressure. This assembly strategy above allows the facile construction of uniform complex nanostructures with ultra-multilayers (≈200). Importantly, it takes much less time than conventional manual manipulation.

Supramolecular Assembly of Photosystem II and Adenosine Triphosphate Synthase in Artificially Designed Honeycomb Multilayers for Photophosphorylation

Plant thylakoids have a typical stacking structure, which is the site of photosynthesis, including light-harvesting, water-splitting, and adenosine triphosphate (ATP) production. This stacking structure plays a key role in exchange of substances with extremely high efficiency and minimum energy consumption through photosynthesis. Herein we report an artificially designed honeycomb multilayer for photophosphorylation. To mimic the natural thylakoid stacking structure, the multilayered photosystem II (PSII)-ATP synthase-liposome system is fabricated via layer-by-layer (LbL) assembly, allowing the three-dimensional distributions of PSII and ATP synthase. Under light illumination, PSII splits water into protons and generates a proton gradient for ATP synthase to produce ATP. Moreover, it is found that the ATP production is extremely associated with the numbers of PSII layers. With such a multilayer structure assembled via LbL, one can better understand the mechanism of PSII and ATP synthase integrated in one system, mimicking the photosynthetic grana structure. On the other hand, such an assembled system can be considered to improve the photophosphorylation.