Gold nanoparticles are popularly used in biological and chemical sensors and their applications owing to their fascinating chemical, optical, and catalytic properties. Particularly, the use of gold ...nanoparticles is widespread in colorimetric assays because of their simple, cost-effective fabrication, and ease of use. More importantly, the gold nanoparticle sensor response is a visual change in color, which allows easy interpretation of results. Therefore, many studies of gold nanoparticle-based colorimetric methods have been reported, and some review articles published over the past years. Most reviews focus exclusively on a single gold nanoparticle-based colorimetric technique for one analyte of interest. In this review, we focus on the current developments in different colorimetric assay designs for the sensing of various chemical and biological samples. We summarize and classify the sensing strategies and mechanism analyses of gold nanoparticle-based detection. Additionally, typical examples of recently developed gold nanoparticle-based colorimetric methods and their applications in the detection of various analytes are presented and discussed comprehensively.
A branched DNA amplification strategy was employed to design a colorimetric aptameric biosensor using unmodified gold nanoparticles (AuNPs). First, a programmed DNA dendritic nanostructure was formed ...using two double-stranded substrate DNAs and two single-stranded auxiliary DNAs as assembly components via a target-assisted cascade amplification reaction, and it was then captured by DNA sensing probe-stabilized AuNPs. The release of sensing probes from AuNPs led to the formation of unstable AuNPs, promoting salt-induced aggregation. By integrating the signal amplification capacity of the branched DNA cascade reaction and unmodified AuNPs as a sensing indicator, this amplified colorimetric sensing strategy allows protein detection with high sensitivity (at the femtomole level) and selectivity. The limit of detection of this approach for VEGF was lower than those of other aptamer-based detection methods. Moreover, this assay provides modification-free and enzyme-free protein detection without sophisticated instrumentation and might be generally applicable to the detection of other protein targets in the future.
•We developed a novel aptasensor composed of nonlinear hybridization chain reaction (NLHCR) and gold nanoparticles.•This assay needs less than an hour for its completion, compared with several hours for HCR-based detection.•Without sacrificing any assay ability, as few as 3.7fmole of proteins could be detected.
In this work, hybridization chain reactions (HCRs) toward
(
) nucleocapsid phosphoproteins gene loci and human RNase P are proposed to provide an isothermal amplification screening tool. The proposed ...chain reactions target the complementary DNA (cDNA) of
, with loci corresponding to gold-standard polymerase chain reaction (PCR) loci. Four hybridization chain reaction reactions are demonstrated herein, targeting
loci and human
. The design of the hybridization chain reaction, herein, is assisted with an algorithm. The algorithm helps to search target sequences with low local secondary structure and high hybridization efficiency. The loop domain of the fuel hairpin molecule H1 and H2, which are the tunable segments in such reactions, are used as an optimization parameter to improve the hybridization efficiency of the chain reaction. The algorithm-derived HCR reactions were validated with gel electrophoresis. All proposed reactions exhibit a hybridization complex with a molecular mass >1.5k base pairs, which is clear evidence of chain reaction. The hybridization efficiency trend revealed by gel electrophoresis corresponds nicely to the simulated data from the algorithm. The HCR reactions and the corresponding algorithm serve as a basis to further
sensing applications and facilitate better screening strategies for the prevention of on-going pandemics.
The explosive growth of smart devices and expansion of network services drives the flourish of mobile applications. Caching popular application services at the edge, BSs, or APs, which are closer to ...end users, could significantly improve the user experience and network capacity. To exploit this potential, it is critical to understand the traffic consumption and app usage pattern under BSs in the metropolitan area. Mobile big data collected from network interfaces facilitates the data-driven approach in characterizing these features. This article aims to design an edge caching strategy for app services based on the observed characteristics of BSs in terms of points of interest (POIs), logs, and traffic generated by various categories of apps. We first analyze the temporal characteristics of different categories of apps, and then further investigate the logs and traffic generated by app types under different BSs clustered by POIs. The top N popular app types in a given period of time under different BS clusters are predicted, which is helpful for network operators to know the traffic distribution of different app services over all BSs and design the edge caching scheme.
Monitoring of structural changes in subcellular organelles is critical to evaluate the chemotherapeutic response of cells. However, commercial organelle selective fluorophores are easily ...photobleached, and thus are unsuitable for real-time and long-term observation. We have developed photostable carbon-dot liposomes (CDsomes)-based fluorophores for organellar and suborganellar imaging to circumvent these issues. The CDs synthesized through a mild pyrolysis/hydrolysis process exhibit amphipathic nature and underwent self-assembly to form liposome–like structures (CDsomes). The controlled hydrophilicity or hydrophobicity-guided preparation of CDsomes are used to selectively and rapidly (<1 min) stain nucleolus, cytoplasm, and membrane. In addition, the CDsomes offer universal high-contrast staining not only in fixed cells but also in living cells, allowing real-time observation and morphological identification in the specimen. The as-prepared CDsomes exhibit excitation-dependent fluorescence, and are much more stable under photoirradiation (e.g., ultraviolet light) than traditional subcellular dyes. Interestingly, the CDsomes can be transferred to daughter cells by diluting the particles, enabling multigenerational tracking of suborganelle for up to six generations, without interrupting the staining pattern. Therefore, we believe that the ultra-photostable CDsomes with high biocompatibility, and long-term suborganellar imaging capabilities, hold a great potential for screening and evaluating therapeutic performance of various chemotherapeutic drugs.
We developed a simple method for the detection of platelet-derived growth factors (PDGFs) based on base stacking effect coupled with an unmodified gold nanoparticle (AuNP) indicator. In the absence ...of a target, an aptamer probe and a capture probe stably co-exist in a solution, as it is difficult to sustain an interaction between both these probes due to the short 8bp duplex. However, when a target protein binds to the aptamer probe, the strong base stacking effect can lead to a favorable and stable interaction between the aptamer and capture probes. Hence, the capture probe dissociates from the AuNP surfaces, inducing AuNP aggregation. Compared with other AuNP-based aptasensors for PDGFs, using this base stacking effect can overcome a structured-aptamer method's limitation of requiring thiolated-aptamer-modified AuNPs. Under optimal detection conditions, this label-free colorimetric sensor could detect PDGFs down to 6nM with high selectivity in the presence of other interferring proteins. This simple detection approach provides viable methods for a structured-aptamer sensing protocol.
Endophthalmitis describes any intraocular inflammation that involves both the posterior and anterior segments and is divided into endogenous and exogenous types according to its pathogenesis. The ...incidence of endophthalmitis and its risk factors have been extensively evaluated. However, few studies have explored the mortality rate in patients diagnosed with endophthalmitis.
We obtained data entered into the National Health Insurance Research Database (NHIRD) from 2000 to 2013. The data collected included all discharge diagnoses of endophthalmitis in inpatients. Baseline characteristics, comorbidities, and prognostic factors were evaluated.
This study identified 7764 patients who were diagnosed with endophthalmitis in Taiwan from 2000 to 2013. The mortality rate was 0.97% (75/7764), and the mean age was 63.57 ± 15.72 years. Epidemiological characteristics were compared as "with or without" for different systemic comorbidities, and the results indicated that the adjusted odds ratio (AOR) was significantly higher in cases comorbid with renal disease (AOR 2.864, P = 0.001), septicemia (AOR 8.886, P < 0.001), pneumonia (AOR 2.072, P = 0.030), and tumors (AOR 7.437, P < 0.001). However, comorbidity with diabetes mellitus (DM) lowered the AOR by 0.500-fold (P = 0.026). There was no significant difference in ORs between patients comorbid with hypertension, depression, anxiety, hyperlipidemia, thyrotoxicosis, liver disease, or injury (all P > 0.05).
Among inpatients with endophthalmitis, predictors of mortality include renal disease, septicemia, pneumonia, neoplasia, a greater burden of comorbidity (especially catastrophic illness), longer hospital stays (more than 11 days), and higher medical costs. Interestingly, DM decreased the OR for inpatient mortality.
This study aimed to evaluate the relationship between diabetic mellitus (DM) treatment and the incidence rate of endogenous endophthalmitis (EE).
This study used a matched cohort design. We utilized ...the Longitudinal Health Insurance Database to identify outpatients and inpatients who were diagnosed with DM and treated with medication from 2000 to 2010.
Several factors and different DM medications were also investigated. The influence of DM medication on the incidence of EE was examined by using Cox proportional hazards regression models, and the hazard ratios and 95% confidence intervals were determined.
The cumulative incidence of EE was lower in DM patients treated with medication than in subjects in the control group (P = 0.002). The adjusted hazard ratio (AHR) was 0.47-fold lower in the treatment group than in the control group (P = 0.004). With respect to DM medication, single-agent therapy with insulin, metformin, gliclazide, glimepiride, or repaglinide and combination therapy with glimepiride/metformin or repaglinide/metformin were associated with decreased AHRs (0.257-0.544, all P<0.05).
Diabetic patients treated with medication had lower AHRs than those in the control group. Further stratification indicated that liver abscess, liver disease DM patients who were treated with medication had a lower risk of developing EE. Several specific DM medications may decrease the incidence of EE.
With the rapid growth of mobile networks and smart devices, a large number of people prefer to visiting video services via mobile devices. This generates massive data traffic, and thus increases the ...load of cellular networks. To deal with it, we need to investigate the usage patterns in the video consumption. In this article, we take a data-driven analysis of mobile video services by classifying them into three major types: traditional video portals, user-generated video services and personalized livestreaming. We collect a large dataset of 25,937,758 logs from 455 thousand users, and we find that 1) for the same kind of video services, users exhibit high loyalty; 2) in consecutive days, the traffic peaks have differences among different service types; 3) more video traffic is generated from personalized livestreaming services, and it keeps increasing after midnight at weekdays in the downtown; 4) traffic consumption of user-generated service exhibits great differences under different functional regions; 5) individual users are prone to click within the same service type but possible different time gaps during the consecutive views. Lastly, we utilize these findings to discuss the potential applications in the improvements of cellular networks and video services.
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