Transdermal drug delivery patches based on hydrogels are widely used for the transdermal delivery of diverse drugs. However, most hydrogels do not exhibit adequate adhesiveness to skin surface. ...Herein, tissue adhesive hydrogels consisting of polyacrylamide/polydopamine (PAM/PDA) hydrogels embedded with extra‐large pore mesoporous silica nanoparticles (XL‐MSNs) are proposed based on the synergy of cohesive and adhesive properties. The incorporation of XL‐MSNs leads to enhanced strength and adhesiveness to skin tissue due to an increased cohesive property derived from molecular interactions between XL‐MSNs and polymer chains. The application of XL‐MSNs to the hydrogel–skin tissue interface leads to a further enhanced adhesiveness due to the adhesive gluing role of XL‐MSNs on the interface. The optimized condition enables a 4.9‐fold increase in adhesion energy on the porcine skin tissue, compared to the control PAM/PDA patch. Strong adhesion is achieved immediately after the hydrogel patch is attached onto the skin as well as the surfaces of other organs. Finally, transdermal drug delivery through porcine skin is demonstrated by using the hydrogel patch, with a model drug loaded in the XL‐MSNs embedded in the patch. These observations indicate a simple but highly effective strategy for preparing a highly adhesive hydrogel patch for transdermal drug delivery.
The incorporation of extra‐large pore mesoporous silica nanoparticles in adhesive polyacrylamide/polydopamine hydrogels and the additional application of the mesoporous silica nanoparticles on the hydrogel–tissue interface lead to a significant enhancement of the strength and adhesiveness of the hydrogel. The rapid adhesion and sustained drug delivery through the skin allow a highly adhesive hydrogel patch for transdermal drug delivery.
One dimensional polyaniline nanowire is an electrically conducting polymer that can be used as an active layer for sensors whose conductivity change can be used to detect chemical or biological ...species. In this review, the basic properties of polyaniline nanowires including chemical structures, redox chemistry, and method of synthesis are discussed. A comprehensive literature survey on chemiresistive/conductometric sensors based on polyaniline nanowires is presented and recent developments in polyaniline nanowire-based sensors are summarized. Finally, the current limitations and the future prospect of polyaniline nanowires are discussed.
A digital fractional-N PLL that employs a high resolution TDC and a truly ΔΣ fractional divider to achieve low in-band noise with a wide bandwidth is presented. The fractional divider employs a ...digital-to-time converter (DTC) to cancel out ΔΣ quantization noise in time domain, thus alleviating TDC dynamic range requirements. The proposed digital architecture adopts a narrow range low-power time-amplifier based TDC (TA-TDC) to achieve sub 1 ps resolution. By using TA-TDC in place of a BBPD, the limit cycle behavior that plagues BB-PLLs is greatly suppressed by the TA-TDC, thus permitting wide PLL bandwidth. The proposed architecture is also less susceptible to DTC nonlinearity and has faster settling and tracking behavior compared to a BB-PLL. Fabricated in 65 nm CMOS process, the prototype PLL achieves better than -106 dBc/Hz in-band noise and 3 MHz PLL bandwidth at 4.5 GHz output frequency using 50 MHz reference. The PLL consumes 3.7 mW and achieves better than 490 fs rms integrated jitter. This translates to a FoM J of -240.5 dB, which is the best among the reported fractional-N PLLs.
Solar irradiance forecasting is fundamental and essential for commercializing solar energy generation by overcoming output variability. Accurate forecasting depends on historical solar irradiance ...data, correlations between various meteorological variables (e.g., wind speed, humidity, and cloudiness), and influences between the weather contexts of spatially adjacent regions. However, existing studies have been limited to spatiotemporal analysis of a few variables, which have clear correlations with solar irradiance (e.g., sunshine duration), and do not attempt to establish atmospheric contextual information from a variety of meteorological variables. Therefore, this study proposes a novel solar irradiance forecasting model that represents atmospheric parameters observed from multiple stations as an attributed dynamic network and analyzes temporal changes in the network by extending existing spatio-temporal graph convolutional network (ST-GCN) models. By comparing the proposed model with existing models, we also investigated the contributions of (i) the spatial adjacency of the stations, (ii) temporal changes in the meteorological variables, and (iii) the variety of variables to the forecasting performance. We evaluated the performance of the proposed and existing models by predicting the hourly solar irradiance at observation stations in the Korean Peninsula. The experimental results showed that the three features are synergistic and have correlations that are difficult to establish using single-aspect analysis.
Stem cells have attracted increasing research interest in the field of regenerative medicine because of their unique ability to differentiate into multiple cell lineages. However, controlling stem ...cell differentiation efficiently and improving the current destructive characterization methods for monitoring stem cell differentiation are the critical issues. To this end, multifunctional graphene–gold (Au) hybrid nanoelectrode arrays (NEAs) to: (i) investigate the effects of combinatorial physicochemical cues on stem cell differentiation, (ii) enhance stem cell differentiation efficiency through biophysical cues, and (iii) characterize stem cell differentiation in a nondestructive real‐time manner are developed. Through the synergistic effects of physiochemical properties of graphene and biophysical cues from nanoarrays, the graphene‐Au hybrid NEAs facilitate highly enhanced cell adhesion and spreading behaviors. In addition, by varying the dimensions of the graphene‐Au hybrid NEAs, improved stem cell differentiation efficiency, resulting from the increased focal adhesion signal, is shown. Furthermore, graphene‐Au hybrid NEAs are utilized to monitor osteogenic differentiation of stem cells electrochemically in a nondestructive real‐time manner. Collectively, it is believed the unique multifunctional graphene‐Au hybrid NEAs can significantly advance stem‐cell‐based biomedical applications.
Multifunctional graphene–Au hybrid nanoelectrode arrays (NEAs) are developed. Owing to the combinatory effect of graphene and biophysical cues, the graphene–Au hybrid NEA shows highly improved cell adhesion and spreading behavior, which results in enhanced osteogenesis. Additionally, improved electrochemical sensitivity allows the monitoring of osteogenic differentiation in a nondestructive real‐time manner.
In this study, we propose a dense frequency-time attentive network (DeFT-AN) for multichannel speech enhancement. DeFT-AN is a mask estimation network that predicts a complex spectral masking pattern ...for suppress-ing the noise and reverberation embedded in the short-time Fourier transform (STFT) of an input signal. The proposed mask estimation network incorporates three different types of blocksfor aggregatinginformationin thespatial, spectral, and temporal dimensions. It utilizes a spectral transformer with a modified feed-forward network and a temporal con-former with sequential dilated convolutions. The use of dense blocks and transformers dedicated to the three differ-ent characteristics of audio signals enables more compre-hensive enhancement in noisy and reverberant environ-ments. The remarkable performance of DeFT-AN over state-of-the-art multichannel models is demonstrated based on two popular noisy and reverberant datasets in terms of various metrics for speech quality and intelligibility.
Record power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) have been obtained with the organic hole transporter 2,2′,7,7′-tetrakis(
N
,
N
-di-
p
...-methoxyphenyl-amine)9,9′-spirobifluorene (spiro-OMeTAD). Conventional doping of spiro-OMeTAD with hygroscopic lithium salts and volatile 4-
tert
-butylpyridine is a time-consuming process and also leads to poor device stability. We developed a new doping strategy for spiro-OMeTAD that avoids post-oxidation by using stable organic radicals as the dopant and ionic salts as the doping modulator (referred to as ion-modulated radical doping). We achieved PCEs of >25% and much-improved device stability under harsh conditions. The radicals provide hole polarons that instantly increase the conductivity and work function (WF), and ionic salts further modulate the WF by affecting the energetics of the hole polarons. This organic semiconductor doping strategy, which decouples conductivity and WF tunability, could inspire further optimization in other optoelectronic devices.
A radical doping approach
In perovskite solar cells, high power conversion efficiencies (PCEs) are usually obtained with an organic hole transporter called spiro-OMeTAD. This material must be doped to have sufficient conductivity and optimal work function, but the conventional process with lithium organic salts requires a long oxidation step that also affects device stability. Zhang
et al
. added spiro-OMeTAD biradical precursors that convert into stable organic monoradicals. Combined with ionic salts, this doping strategy formed solar cells with high PCEs (>25%) and improved stability. This approach also allows conductivity and work function to be tuned separately and could be applied in other optoelectronic devices. —PDS
Organic radicals and ionic salts enable doping of an organic hole transporter without post-oxidation treatments.
Metformin reduces insulin resistance, which constitutes a pathophysiological connection of diabetes with Alzheimer's disease (AD), but the evidence of metformin on AD development was still ...insufficient and conflicting. We investigated AD risk in patients with newly diagnosed type 2 DM treated with metformin. This retrospective, observational, nested case-control study included patients with newly diagnosed type 2 DM obtained from the Korean National Health Insurance Service DM cohort (2002-2017). Among 70,499 dementia-free DM patients, 1675 AD cases were matched to 8375 controls for age, sex, and DM onset and duration. The association between AD and metformin was analyzed by multivariable regression analyses, adjusted for comorbidities and cardiometabolic risk profile. Metformin use was associated with an increased odds of AD (adjusted odds ratio AOR 1.50; 95% CI 1.23-1.83). The risk of AD was higher in patients with a longer DM duration. Furthermore, AD risk was significantly high in DM patients with depression (AOR 2.05; 95% CI 1.02-4.12). Given the large number of patients with DM who are taking metformin worldwide, a double-blinded, prospective study is required to determine the long-term cognitive safety of metformin.
Graphene, a single atom thick layer of two-dimensional closely packed honeycomb carbon lattice, and its derivatives have attracted much attention in the field of biomedical, due to its unique ...physicochemical properties. The valuable physicochemical properties, such as high surface area, excellent electrical conductivity, remarkable biocompatibility and ease of surface functionalization have shown great potentials in the applications of graphene-based bioelectronics devices, including electrochemical biosensors for biomarker analysis. In this review, we will provide a selective overview of recent advances on synthesis methods of graphene and its derivatives, as well as its application to electrochemical biosensor development. We believe the topics discussed here are useful, and able to provide a guideline in the development of novel graphene and on graphene-like 2-dimensional (2D) materials based biosensors in the future.
Nanoparticle‐based nucleic acid conjugates (NP‐NACs) hold great promise for theragnostic applications. However, several limitations have hindered the realization of their full potential in the ...clinical treatment of cancer and other diseases. In diagnoses, NP‐NACs suffer from low signal‐to‐noise ratios, while the efficiency of NP‐NACs‐mediated cancer therapies has been limited by the adaptation of alternative prosurvival pathways in cancer cells. The recent emergence of personalized and precision medicine has outlined the importance of having both accurate diagnosis and efficient therapeutics in a single platform. As such, the controlled assembly of hybrid graphene oxide/gold nanoparticle (Au@GO NP)‐based cancer‐specific NACs (Au@GO NP‐NACs) for multimodal imaging and combined therapeutics is reported. The developed Au@GO NP‐NACs show excellent surface‐enhanced Raman scattering (SERS)‐mediated live‐cell cancer detection and multimodal synergistic cancer therapy through the use of photothermal, genetic, and chemotherapeutic strategies. Synergistic and selective killing of cancer cells are then demonstrated using in vitro microfluidic models. Moreover, with the distinctive advantages of the Au@GO NP‐NACs for cancer theragnostics, precision cancer treatment through the detection of cancer cells in vivo using SERS followed by efficient ablation of tumors is shown. Therefore, the Au@GO NP‐NACs can pave a new road for advanced disease theragnostics.
Effective modulation of the tumor microenvironment requires both efficient delivery of anticancer therapeutics and robust imaging modalities. By incorporating surface‐enhanced Raman scattering imaging and photothermal‐gene therapies, graphene/gold nanoparticle‐based nucleic acid conjugates (Au@GO‐NAC) are developed. By suppressing the growth of 9 cancer cell lines in vitro and effectively ablating tumors in vivo, Au@GO‐NACs show excellent potential for next‐generation cancer nanomedicine.
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