Staff directory Liming Hu



  • Improved Aliivibrio fischeri based-toxicity assay: Graphene-oxide as a sensitivity booster with a mobile-phone application

    Bergua J.F., Álvarez-Diduk R., Hu L., Hassan A.H.A., Merkoçi A. Journal of Hazardous Materials; 406 (124434) 2021. 10.1016/j.jhazmat.2020.124434. IF: 10.588

    Recently, many bioluminescence-based applications have arisen in several fields, such as biosensing, bioimaging, molecular biology, and human health diagnosis. Among all bioluminescent organisms, Aliivibrio fischeri (A. fischeri) is a bioluminescent bacterium used to carry out water toxicity assays since the late 1970s. Since then, several commercial A. fischeri-based products have been launched to the market, as these bacteria are considered as a gold standard for water toxicity assessment worldwide. However, the aforementioned commercial products rely on expensive equipment, requiring several reagents and working steps, as well as high-trained personnel to perform the assays and analyze the output data. For these reasons, in this work, we have developed for the first time a mobile-phone-based sensing platform for water toxicity assessment in just 5 min using two widespread pesticides as model analytes. To accomplish this, we have established new methodologies to enhance the bioluminescent signal of A. fischeri based on the bacterial culture in a solid media and/or using graphene oxide. Finally, we have addressed the biocompatibility of graphene oxide to A. fischeri, boosting the sensitivity of the toxicity assays and the bacterial growth of the lyophilized bacterial cultures for more user-friendly storage. © 2020 Elsevier B.V.

  • Lateral flow device for water fecal pollution assessment: From troubleshooting of its microfluidics using bioluminescence to colorimetric monitoring of genericEscherichia coli

    Bergua J.F., Hu L., Fuentes-Chust C., Álvarez-Diduk R., Hassan A.H.A., Parolo C., Merkoçi A. Lab on a Chip; 21 (12): 2417 - 2426. 2021. 10.1039/d1lc00090j. IF: 6.799

    Water is the most important ingredient of life. Water fecal pollution threatens water quality worldwide and has direct detrimental effects on human health and the global economy. Nowadays, assessment of water fecal pollution relies on time-consuming techniques that often require well-trained personnel and highly-equipped laboratories. Therefore, faster, cheaper, and easily-used systems are needed toin situmonitor water fecal pollution. Herein, we have developed colorimetric lateral flow strips (LFS) able to detect and quantifyEscherichia colispecies in tap, river, and sewage water samples as an indicator of fecal pollution. The combination of LFS with a simple water filtration unit and a commercially available colorimetric reader enhanced the assay sensitivity and enabled more accurate quantification of bacteria concentration down to 104CFU mL−1in 10 minutes, yielding recovery percentages between 80% and 90% for all water samples analyzed. Overall, this system allows for monitoring and assessing water quality based onE. colispecies as a standard microbiological indicator of fecal pollution. Furthermore, we have developed a novel bioluminescent, bacteria-based method to quickly characterize the performance of a great variety of LFS materials. This new method allows evaluating the flow rate of big analytes such as bacteria through the LFS materials, as a suggestive means for selecting the appropriate materials for fabricating LFS targeting big analytes (≈2 μm). As a whole, the proposed approach can accelerate and reduce the costs of water quality monitoring and pave the way for further improvement of fecal pollution detection systems. © The Royal Society of Chemistry 2021.

  • Nanodiagnostics to Face SARS-CoV-2 and Future Pandemics: From an Idea to the Market and beyond

    Rosati G., Idili A., Parolo C., Fuentes-Chust C., Calucho E., Hu L., Castro E Silva C.D.C., Rivas L., Nguyen E.P., Bergua J.F., Alvárez-Diduk R., Muñoz J., Junot C., Penon O., Monferrer D., Delamarche E., Merkoçi A. ACS Nano; 15 (11): 17137 - 17149. 2021. 10.1021/acsnano.1c06839. IF: 15.881

    The COVID-19 pandemic made clear how our society requires quickly available tools to address emerging healthcare issues. Diagnostic assays and devices are used every day to screen for COVID-19 positive patients, with the aim to decide the appropriate treatment and containment measures. In this context, we would have expected to see the use of the most recent diagnostic technologies worldwide, including the advanced ones such as nano-biosensors capable to provide faster, more sensitive, cheaper, and high-throughput results than the standard polymerase chain reaction and lateral flow assays. Here we discuss why that has not been the case and why all the exciting diagnostic strategies published on a daily basis in peer-reviewed journals are not yet successful in reaching the market and being implemented in the clinical practice. ©


  • Lateral flow assay modified with time-delay wax barriers as a sensitivity and signal enhancement strategy

    Sena-Torralba A., Ngo D.B., Parolo C., Hu L., Álvarez-Diduk R., Bergua J.F., Rosati G., Surareungchai W., Merkoçi A. Biosensors and Bioelectronics; 168 (112559) 2020. 10.1016/j.bios.2020.112559. IF: 10.257

    The ease of use, low cost and quick operation of lateral flow assays (LFA) have made them some of the most common point of care biosensors in a variety of fields. However, their generally low sensitivity has limited their use for more challenging applications, where the detection of low analytic concentrations is required. Here we propose the use of soluble wax barriers to selectively and temporarily accumulate the target and label nanoparticles on top of the test line (TL). This extended internal incubation step promotes the formation of the immune-complex, generating a 51.7-fold sensitivity enhancement, considering the limit of quantification, and up to 96% signal enhancement compared to the conventional LFA for Human IgG (H-IgG) detection. © 2020 Elsevier B.V.

  • Tutorial: design and fabrication of nanoparticle-based lateral-flow immunoassays

    Parolo C., Sena-Torralba A., Bergua J.F., Calucho E., Fuentes-Chust C., Hu L., Rivas L., Álvarez-Diduk R., Nguyen E.P., Cinti S., Quesada-González D., Merkoçi A. Nature Protocols; 15 (12): 3788 - 3816. 2020. 10.1038/s41596-020-0357-x. IF: 10.419

    Lateral-flow assays (LFAs) are quick, simple and cheap assays to analyze various samples at the point of care or in the field, making them one of the most widespread biosensors currently available. They have been successfully employed for the detection of a myriad of different targets (ranging from atoms up to whole cells) in all type of samples (including water, blood, foodstuff and environmental samples). Their operation relies on the capillary flow of the sample throughout a series of sequential pads, each with different functionalities aiming to generate a signal to indicate the absence/presence (and, in some cases, the concentration) of the analyte of interest. To have a user-friendly operation, their development requires the optimization of multiple, interconnected parameters that may overwhelm new developers. In this tutorial, we provide the readers with: (i) the basic knowledge to understand the principles governing an LFA and to take informed decisions during lateral flow strip design and fabrication, (ii) a roadmap for optimal LFA development independent of the specific application, (iii) a step-by-step example procedure for the assembly and operation of an LF strip for the detection of human IgG and (iv) an extensive troubleshooting section addressing the most frequent issues in designing, assembling and using LFAs. By changing only the receptors, the provided example procedure can easily be adapted for cost-efficient detection of a broad variety of targets. © 2020, The Author(s), under exclusive licence to Springer Nature Limited.