No abstract

To overcome the spatiotemporal barriers to conventional stimuli-responsive polymeric materials, we report a photo-responsive self-reducible polymer with a built-in photo-locked stimulus precursor derived from dithiothreitol. The smart polymer could hierarchically self-assemble into a layered vesicular structure in an aqueous solution, and undergo a self-cleavage of l-cystine residues in the backbone, in response to reducing moieties uncaged by ultraviolet light in the side chains. The photo-generation of stimulus in situ can potentially overcome the steric hindrance and temporal limitation, leading to a site-specific and ultrafast release of payloads for effective delivery of therapeutics. Our work provides a new approach to the development of smart responsive biodegradable polymers.

As an indispensable constituent of plasmonic materials/dielectrics for surface enhanced Raman scattering (SERS) effects, dielectrics play a key role in excitation and transmission of surface plasmons which however remain more elusive relative to plasmonic materials. Herein, different roles of vertical dielectric walls, and horizontal and vertical dielectric layers in SERS via 3D periodic plasmonic materials/dielectrics structures are studied. Surface plasmon polariton (SPP) interferences can be maximized within dielectric walls besieged by plasmonic layers at the wall thicknesses of integral multiple half-SPP plasmonic material-dielectric -wavelength which effectively excites localized surface plasmon resonance to improve SERS effects by one order of magnitude compared to roughness and/or nanogaps only. The introduction of extra Au nanoparticles on thin dielectric layers can further enhance SERS effects only slightly. Thus, the designed Au/SiO 2 based SERS chips show an enhancement factor of 8.9 × 10 10 , 265 times higher relative to the chips with far thinner SiO 2 walls. As many as 1200 chips are batch fabricated for a 4 in wafer using cost-effective nanoimprint lithography which can detect trace Hg ions as low as 1 ppt. This study demonstrates a complete generalized platform from design to low-cost batch-fabrication to applications for novel high performance SERS chips of any plasmonic materials/dielectrics.

The applications of bioresponsive materials are limited by the low levels of physiological triggers and spatiotemporal barriers in vivo. To address these issues, a light‐controlled “Trojan horse” strategy is proposed by encapsulating a photo‐caged reducing agent within reduction‐responsive polymer vesicles. The polymersomes act as an enzyme‐inspired nanoreactor for efficient photo‐synthesis of dithiothreitol in situ, which attacks the disulfide bonds in polymer backbones and disintegrates the vehicles from the inside in a nanoconfined space. The assembly‐catalyzed photoreduction reaction overcomes the temporal and spatial barriers for hyper‐responsivity and enables ultrafast drug release even at 0.014 mm of dithiothreitol residues, a concentration 715 times lower than that required to cleave disulfide bonds. In addition, in both vitro and vivo, the equipment of upconverting nanoparticles and photothermal agents creates a near‐infrared light‐activated and self‐heating nanoreactor, which allows for efficient intracellular drug delivery and excellent photo‐chemo‐immunotherapy of tumors. This work presents a new approach to designing smart materials and a promising platform for on‐demand drug delivery applications.