Lipase‐Triggered Water‐Responsive “Pandora's Box” for Cancer Therapy: Toward Induced Neighboring Effect and Enhanced Drug Penetration

Insufficient drug release as well as poor drug penetration are major obstacles for effective nanoparticles (NPs)‐based cancer therapy. Herein, the high aqueous instability of amorphous calcium carbonate (ACC) is employed to construct doxorubicin (DOX) preloaded and monostearin (MS) coated “Pandora's box” (MS/ACC–DOX) NPs for lipase‐triggered water‐responsive drug release in lipase‐overexpressed tumor tissue to induce a neighboring effect and enhance drug penetration. MS as a solid lipid can prevent potential drug leakage of ACC–DOX NPs during the circulatory process, while it can be readily be disintegrated in lipase‐overexpressed SKOV3 cells to expose the ACC–DOX core. The high aqueous instability of ACC will lead to burst release of the encapsulated DOX to induce apoptosis and cytotoxicity to kill the tumor cells. The liberated NPs from the dead or dying cells continue to respond to the ubiquitous aqueous environment to sufficiently release DOX once unpacked, like the “Pandora's box”, leading to severe cytotoxicity to neighboring cells (neighboring effect). Moreover, the continuously released free DOX molecules can readily diffused through the tumor extracellular matrix to enhance drug penetration to deep tumor tissue. Both effects contribute to achieve elevated antitumor benefits.     

Cancer‐Cell Targeting and Photoacoustic Therapy Using Carbon Nanotubes as “Bomb” Agents

A unique approach using the large photoacoustic effect of single‐walled carbon nanotubes (SWNTs) for targeting and selective destruction of cancer cells is demonstrated. SWNTs exhibit a large photoacoustic effect in suspension under the irradiation of a 1064‐nm Q‐switched millisecond pulsed laser and trigger a firecracker‐like explosion at the nanoscale. By using such an explosion, a photoacoustic agent is developed by functionalizing the SWNTs with folate acid (FA) that can selectively bind to cancer cells overexpressing folate receptor on the surface of the cell membrane and kill them through SWNT explosion inside the cells under the excitation of millisecond pulsed laser. The uptake pathway of folate‐conjugated SWNTs into cancer cells is investigated via fluorescence imaging and it is found that the FA‐SWNTs can enter into cancer cells selectively with a high targeting capability of 17–28. Under the treatment of 1064‐nm millisecond pulsed laser, 85% of cancer cells with SWNT uptake die within 20 s, while 90% of the normal cells remain alive due to the lack of SWNTs inside cells. Temperature changes during laser treatment are monitored and no temperature increases of more than ± 3 °C are observed. With this approach, the laser power used for cancer killing is reduced 150–1500 times and the therapy efficiency is improved. The death mechanism of cancer cells caused by the photoacoustic explosion of SWNTs is also studied and discussed in detail. These discoveries provide a new way to use the photoacoustic properties of SWNTs for therapeutic applications.     

Functional Adhesive Surfaces with “Gecko” Effect: The Concept of Contact Splitting

Nature has developed reversibly adhesive surfaces whose stickiness has attracted much research attention over the last decade. The central lesson from nature is that “patterned” or “fibrillar” surfaces can produce higher adhesion forces to flat and rough substrates than smooth surfaces. This paper critically examines the principles behind fibrillar adhesion from a contact mechanics perspective, where much progress has been made in recent years. The benefits derived from “contact splitting” into fibrils are separated into extrinsic/intrinsic contributions from fibril deformation, adaptability to rough surfaces, size effects due to surface‐to‐volume ratio, uniformity of stress distribution, and defect‐controlled adhesion. Another section covers essential considerations for reliable and reproducible adhesion testing, where better standardization is still required. It is argued that, in view of the large number of parameters, a thorough understanding of adhesion effects is required to enable the fabrication of reliable adhesive surfaces based on biological examples.     

Chasing the “Killer” Phonon Mode for the Rational Design of Low‐Disorder,High‐Mobility Molecular Semiconductors

Molecular vibrations play a critical role in the charge transport properties of weakly van der Waals bonded organic semiconductors. To understand which specific phonon modes contribute most strongly to the electron–phonon coupling and ensuing thermal energetic disorder in some of the most widely studied high‐mobility molecular semiconductors, state‐of‐the‐art quantum mechanical simulations of the vibrational modes and the ensuing electron–phonon coupling constants are combined with experimental measurements of the low‐frequency vibrations using inelastic neutron scattering and terahertz time‐domain spectroscopy. In this way, the long‐axis sliding motion is identified as a “killer” phonon mode, which in some molecules contributes more than 80% to the total thermal disorder. Based on this insight, a way to rationalize mobility trends between different materials and derive important molecular design guidelines for new high‐mobility molecular semiconductors is suggested.     

Conjuncted Pyro‐Piezoelectric Effect for Self‐Powered Simultaneous Temperature and Pressure Sensing

Ferroelectric materials use both the pyroelectric effect and piezoelectric effect for energy conversion. A ferroelectric BaTiO₃‐based pyro‐piezoelectric sensor system is demonstrated to detect temperature and pressure simultaneously. The voltage signal of the device is found to enhance with increasing temperature difference with a sensitivity of about 0.048 V °C^?1 and with applied pressure with a sensitivity of about 0.044 V kPa^?1. Moreover, no interference appears in the output voltage signals when piezoelectricity and pyroelectricity are conjuncted in the device. A novel 4 × 4 array sensor system is developed to sense real‐time temperature and pressure variations induced by a finger. This system has potential applications in machine intelligence and man–machine interaction.     

A “Phase Separation” Molecular Design Strategy Towards Large‐Area 2D Molecular Crystals

2D molecular crystals (2DMCs) have attracted considerable attention because of their unique optoelectronic properties and potential applications. Taking advantage of the solution processability of organic semiconductors, solution self‐assembly is considered an effective way to grow large‐area 2DMCs. However, this route is largely blocked because a precise molecular design towards 2DMCs is missing and little is known about the relationship between 2D solution self‐assembly and molecular structure. A “phase separation” molecular design strategy towards 2DMCs is proposed and layer‐by‐layer growth of millimeter‐sized monolayer or few‐layer 2DMCs is realized. High‐performance organic phototransistors are constructed based on the 2DMCs with unprecedented photosensitivity (2.58 × 10⁷), high responsivity (1.91 × 10⁴ A W^?1), and high detectivity (4.93 × 10¹⁵ Jones). This “phase separation” molecular design strategy provides a guide for the design and synthesis of novel organic semiconductors that self‐assemble into large‐area 2DMCs for advanced organic (opto)electronics.