We have developed model light-emitting metallogels functionalized with lanthanide metal-ligand coordination complexes via a terpyridyl-end-capped four-arm poly(ethylene glycol) polymer. The optical properties of these highly luminescent polymer networks are readily modulated over a wide spectrum, including white-light emission, simply by tuning of the lanthanide metal ion stoichiometry. Furthermore, the dynamic nature of the Ln-N coordination bonding leads to a broad variety of reversible stimuli-responsive properties (mechano-, vapo-, thermo-, and chemochromism) of both sol-gel systems and solid thin films. The versatile functional performance combined with the ease of assembly suggests that this lanthanide coordination polymer design approach offers a robust pathway for future engineering of multi-stimuli-responsive polymer materials.

Interactions between polymer molecules and inorganic nanoparticles can play a dominant role in nanocomposite material mechanics, yet control of such interfacial interaction dynamics remains a significant challenge particularly in water. This study presents insights on how to engineer hydrogel material mechanics via nanoparticle interface-controlled cross-link dynamics. Inspired by the adhesive chemistry in mussel threads, we have incorporated iron oxide nanoparticles (Fe3O4 NPs) into a catechol-modified polymer network to obtain hydrogels cross-linked via reversible metal-coordination bonds at Fe3O4 NP surfaces. Unique material mechanics result from the supra-molecular cross-link structure dynamics in the gels; in contrast to the previously reported fluid-like dynamics of transient catechol–Fe3+ cross-links, the catechol–Fe3O4 NP structures provide solid-like yet reversible hydrogel mechanics. The structurally controlled hierarchical mechanics presented here suggest how to develop hydrogels with remote-controlled self-healing dynamics.

Tuning the threshold voltage of a transistor is crucial for realizing robust digital circuits. For silicon transistors, the threshold voltage can be accurately controlled by doping. However, it remains challenging to tune the threshold voltage of single-wall nanotube (SWNT) thin-film transistors. Here, we report a facile method to controllably n-dope SWNTs using 1H-benzoimidazole derivatives processed via either solution coating or vacuum deposition. The threshold voltages of our polythiophene-sorted SWNT thin-film transistors can be tuned accurately and continuously over a wide range. Photoelectron spectroscopy measurements confirmed that the SWNT Fermi level shifted to the conduction band edge with increasing doping concentration. Using this doping approach, we proceeded to fabricate SWNT complementary inverters by inkjet printing of the dopants. We observed an unprecedented noise margin of 28 V at V DD = 80 V (70% of 1/2V DD ) and a gain of 85. Additionally, robust SWNT complementary metal−oxide−semiconductor inverter (noise margin 72% of 1/2V DD ) and logic gates with rail-torail output voltage swing and subnanowatt power consumption were fabricated onto a highly flexible substrate. nanomaterials | n-doping | inkjet-printed | CMOS circuit F lexible electronics have attracted increasing attention recently due to the plethora of possible and realized applications in radio-frequency identification cards (1, 2), flexible displays (3, 4), and digital processors (5). Solution-processed single-walled carbon nanotubes (SWNTs) are a promising candidate for flexible circuits due to their high charge carrier mobility (6), excellent flexibility/stretchability (7-9), and their compatibility with lowcost, large-area manufacturing processes, such as printing (1, 10) of SWNTs. Their applications in thin-film transistors (TFTs) and integrated logic circuits (11-14) have been demonstrated. However, to achieve robust digital circuits with high immunity against the influence of electronic noise in the system, it is important to be able to control the specific value of the threshold voltage of a transistor during the fabrication process (15,16). This is because transistor threshold voltage determines the input voltage at which a circuit switches between two logic states (trip voltage of an inverter). When the trip voltage is half of the supply voltage, the circuit has the largest noise margin, which is a quantitative measure of the immunity of a logic circuit against noise and a figure of merit to characterize the robustness of the circuit (17, 18). If threshold voltage cannot be controlled during the fabrication process, the resulting circuit might not work reliably due to the electrical noise that is always present in the system. Because SWNTs have ambipolar electrical transport properties (19), accurately tuning the threshold voltage permits the construction of complementary metal−oxide−semiconductor (CMOS) circuits that use both the p-type and n-type character of SWNTs. The advantages of CMOS circuits compared with unipolar ...

approaches. While addressing the limitations of the electrical counterparts (e.g., massive amounts of radio frequency (RF) cabling and electromagnetic (EM) interference), a photoacoustic approach for gene rat ing high-amplitude ultrasound has created new opportunities.Active research on efficient photo acoustic materials has started with the development of photoacoustic contrast mediums (e.g., exogenous contrast particles) for contrast enhancement. [3][4][5] Recent advances in nanofabrication technologies have allowed to develop more efficient photoacoustic contrast mediums, [3] such as metal nanoparticles having enhanced optical absorption due to optical resonance. Later, by coating such nanoparticles on a flat substrate, layered structures were developed for generating high-amplitude ultrasound. Among many nanoparticles, gold nanoparticles were widely used owing to strong resonance. [6] In fact, these initial efforts to increase photoacoustic conversion were focused on increasing light absorption, while the critical role of thermal expansion for photoacoustic generation were often overlooked.To enhance thermal expansion for photoacoustic generation, researchers have started to fabricate composite materials, composed of light-absorbing materials mixed with polymers with high thermal expansion coefficients. These polymer-based composites significantly enhance photoacoustic conversion efficiency. Among many polymers, polydimethylsiloxane (PDMS) is exclusively used because of its high thermal expansion, optical transparency, and acoustic impedance comparable to that of water. [7][8][9][10][11] Photoacoustic pulses generated with PDMSbased composites have the characteristics of high amplitude and high frequency, which have enabled interesting applications such as cavitation-based therapy [12] and imaging. [13] For photoacoustic composites, there are a myriad of light-absorbing nanomaterials such as metal absorbers [6] and carbon nanomaterials (e.g., carbon black (CB), [14] carbon nanotube (CNT), [7,10] carbon nanofiber (CNF), [9] candle soot (CS), [8] and reduced graphene oxide (rGO) [15] ). These light-absorbing materials of nanometer sizes have an advantage over microscale absorbing materials [7] in facilitating heat transfer from the light absorbers into the surrounding mediums. Such facilitated heat transfer is another key factor that contributes to photoacoustic energy conversion.In this Review, we will start with general considerations of photoacoustic generation in nanomaterial composites. Various photoacoustic composites enabling interesting applications will be introduced. In addition, recent efforts will be reviewed from an application perspective. Also, we will discuss outlook and future directions.Photoacoustic pulses generated by pulsed laser irradiation have the characteristics of high frequency and wide bandwidth, which are desirable for imaging and sensing. Efficient photoacoustic composites have been developed for fabricating photoacoustic transmitters capable of generating highamplitude ultrasound....

Kinesin-1 (hereafter referred to as kinesin) is a major microtubule-based motor protein for plus-end-directed intracellular transport in live cells. While the single-molecule functions of kinesin are well characterized, the physiologically relevant transport of membranous cargos by small teams of kinesins remains poorly understood. A key experimental challenge remains in the quantitative control of the number of motors driving transport. Here we utilized "motile fraction" to overcome this challenge and experimentally accessed transport by a single kinesin through the physiologically relevant transport by a small team of kinesins. We used a fluid lipid bilayer to model the cellular membrane in vitro and employed optical trapping to quantify the transport of membrane-enclosed cargos versus traditional membrane-free cargos under identical conditions. We found that coupling motors via a fluid membrane significantly enhances the velocity of cargo transport by small teams of kinesins. Importantly, enclosing a cargo in a fluid lipid membrane did not impact single-kinesin transport, indicating that membrane-dependent velocity enhancement for team-based transport arises from altered interactions between kinesins. Our study demonstrates that membrane-based coupling between motors is a key determinant of kinesin-based transport. Enhanced velocity may be critical for fast delivery of cargos in live cells.