An emerging assay for rapid diagnosis of live Salmonella Typhimurium by exploiting aqueous/liquid crystal interface.

The rapid and accurate identification of live pathogens with high proliferative ability is in great demand to mitigate foodborne infection outbreaks. Herein, we have developed an ultrasensitive image-based aptasensing array to directly detect live Salmonella typhimurium (S.T) cells. This method relies on the long-range orientation of surfactant-decorated liquid crystals (LCs) and the superiority of aptamers (aptST). The self-assembling of hydrophobic surfactant tails leads to a perpendicular/vertical ordered film at the aqueous/LC interface and signal-off response. The addition of aptST perturbed LCs' ordering into a planar/tilted state at the aqueous phase due to electrostatic interactions between the surfactant with the aptST, and a signal-on response. Following the conformational switch of aptST in the presence of live S. typhimurium, a relative reversing signal-off response was observed upon the target concentration. This aptasensor could promptly confirm the presence of S. typhimurium without intricate DNA-extraction or pre-enrichment stats over a linear range of 1-1.1 × 106 CFU/mL and a detection limit of 1.2 CFU/mL within ∼30 min. These results were successfully validated using molecular and culture-based methods in spiked-milk samples, with a 92.61-104.61 % recovery value. Meanwhile, the flexibility of this portable sensing platform allows for its development and adoption for the precise detection of various pathogens in food and the environment.

Opto-microfluidic assisted synthesis of photo-protoporphyrin (pPP) conjugated to hollow gold-albumin hybrid nanoshells to enhance the efficiency of photodynamic therapy of triple negative breast cancer cells.

INTRODUCTION: Protoporphyrin-IX (PpIX), a photosensitizer used in photodynamic therapy, has limitations due to its hydrophobicity, rapid photobleaching, and low absorption peak in the red region. These limitations make the use of PpIX less effective for photodynamic therapy treatments. In this study, we harnessed the power of microfluidic technology to manipulate the properties of PpIX and quickly synthesize albumin-based hybrid nanoshells with high reproducibility. METHODS AND MATERIAL: To begin with, we designed a microfluidic chip with SolidWorksⓇ software; then the chip was fabricated in Poly(methyl methacrylate) (PMMA) material using micromilling and thermal bonding. We synthesized PpIX-loaded CTAB micelles and subsequently transformed the PpIX structure into photo-protoporphyrin (PPP,) by opto-microfluidic chip (Integrating a microfluidic chip with a light source). Simultaneously with CTAB-PPP synthesis complex, we trapped it in binding sites of bovine serum albumin (BSA). Afterward, we used the same method (without irradiating) to generate a hybrid nanostructure consisting of hollow gold nanoshells (HGN) and BSACTAB-PPP. Then, after physical characterization of nanostructures, the photodynamic effects of the agents (HGNs, CTAB-PpIX, BSA-CTABPpIX, HGN-BSA-CTAB-PpIX, CTAB-PPP, BSA-CTAB-PPP, and HGNs-BSA-CTAB-PPP) were evaluated on MDA-MB-231 and 4T1 cells and the cytotoxic properties of the therapeutic agents after treatment for 24, 48, and 72 hours were investigated using MTT assay. Finally, we analyzed the findings using GraphPad Prism 9.0 software. RESULTS: Results revealed that the opto-microfluidic assisted synthesis of HGN-BSA-CTAB-PPP is highly efficient and reproducible, with a size of 120 nm, a zeta potential of -16 mV, and a PDI index of 0.357. Furthermore, the cell survival analysis demonstrated that the HGNBSA-CTAB-PPP hybrid nanostructure can significantly reduce the survival of MDA-MB-231 and 4T1 cancer cells at low radiation doses (< 10 J/cm2) when exposed to an incoherent light source due to its strong absorption peak at a wavelength of 670 nm. CONCLUSION: This research indicates that developing albumin-based multidrug hybrid nanostructures using microfluidic technology could be a promising approach to design more efficient photodynamic therapy studies.

Superparamagnetic cobalt ferrite nanoparticles as T2 contrast agent in MRI: in vitro study.

Superparamagnetic cobalt ferrite nanoparticles (CoFe2O4) possess favourite advantages for theranostic applications. Most of previous studies reported that CoFe2O4 magnetic nanoparticles (MNPs) are suitable candidates for induction of hyperthermia and transfection agents for drug delivery. The present study synthesized and investigated the potential use of CoFe2O4 as a contrast agent in magnetic resonance imaging (MRI) by using a conventional MRI system. The CoFe2O4 were synthesized using co-precipitation method and characterized by TEM, XRD, FTIR, EDX and VSM techniques. Relaxivities r1 and r2 of CoFe2O4 were then calculated using a 1.5 Tesla clinical magnetic field. The cytotoxicity of CoFe2O4 was evaluated by the MTT assay. Finally, the optimal concentrations of MNPs for MRI uses were calculated through the analysis of T2 weighted imaging cell phantoms. The superparamagnetic CoFe2O4 NPs with an average stable size of 10.45 nm were synthesized. Relaxivity r1,2 calculations resulted in suitable r2 and r2/ r1 with values of 58.6 and 51 that confirmed the size dependency on relaxivity values. The optimal concentration of MNPs for MR image acquisition was calculated as 0.154 mM. Conclusion: CoFe2O4 synthesized in this study could be considered as a suitable T2 weighted contrast agent because of its high r2/r1 value.

Automated microfluidic platform of bead-based electrochemical immunosensor integrated with bioreactor for continual monitoring of cell secreted biomarkers.

There is an increasing interest in developing microfluidic bioreactors and organs-on-a-chip platforms combined with sensing capabilities for continual monitoring of cell-secreted biomarkers. Conventional approaches such as ELISA and mass spectroscopy cannot satisfy the needs of continual monitoring as they are labor-intensive and not easily integrable with low-volume bioreactors. This paper reports on the development of an automated microfluidic bead-based electrochemical immunosensor for in-line measurement of cell-secreted biomarkers. For the operation of the multi-use immunosensor, disposable magnetic microbeads were used to immobilize biomarker-recognition molecules. Microvalves were further integrated in the microfluidic immunosensor chip to achieve programmable operations of the immunoassay including bead loading and unloading, binding, washing, and electrochemical sensing. The platform allowed convenient integration of the immunosensor with liver-on-chips to carry out continual quantification of biomarkers secreted from hepatocytes. Transferrin and albumin productions were monitored during a 5-day hepatotoxicity assessment in which human primary hepatocytes cultured in the bioreactor were treated with acetaminophen. Taken together, our unique microfluidic immunosensor provides a new platform for in-line detection of biomarkers in low volumes and long-term in vitro assessments of cellular functions in microfluidic bioreactors and organs-on-chips.

Google Glass-Directed Monitoring and Control of Microfluidic Biosensors and Actuators.

Google Glass is a recently designed wearable device capable of displaying information in a smartphone-like hands-free format by wireless communication. The Glass also provides convenient control over remote devices, primarily enabled by voice recognition commands. These unique features of the Google Glass make it useful for medical and biomedical applications where hands-free experiences are strongly preferred. Here, we report for the first time, an integral set of hardware, firmware, software, and Glassware that enabled wireless transmission of sensor data onto the Google Glass for on-demand data visualization and real-time analysis. Additionally, the platform allowed the user to control outputs entered through the Glass, therefore achieving bi-directional Glass-device interfacing. Using this versatile platform, we demonstrated its capability in monitoring physical and physiological parameters such as temperature, pH, and morphology of liver- and heart-on-chips. Furthermore, we showed the capability to remotely introduce pharmaceutical compounds into a microfluidic human primary liver bioreactor at desired time points while monitoring their effects through the Glass. We believe that such an innovative platform, along with its concept, has set up a premise in wearable monitoring and controlling technology for a wide variety of applications in biomedicine.

Microfluidics for Advanced Drug Delivery Systems.

Considerable efforts have been devoted towards developing effective drug delivery methods. Microfluidic systems, with their capability for precise handling and transport of small liquid quantities, have emerged as a promising platform for designing advanced drug delivery systems. Thus, microfluidic systems have been increasingly used for fabrication of drug carriers or direct drug delivery to a targeted tissue. In this review, the recent advances in these areas are critically reviewed and the shortcomings and opportunities are discussed. In addition, we highlight the efforts towards developing smart drug delivery platforms with integrated sensing and drug delivery components.

Design, fabrication and characterization of drug delivery systems based on lab-on-a-chip technology.

Lab-on-a-chip technology is an emerging field evolving from the recent advances of micro- and nanotechnologies. The technology allows the integration of various components into a single microdevice. Microfluidics, the science and engineering of fluid flow in microscale, is the enabling underlying concept for lab-on-a-chip technology. The present paper reviews the design, fabrication and characterization of drug delivery systems based on this amazing technology. The systems are categorized and discussed according to the scales at which the drug is administered. Starting with the fundamentals on scaling laws of mass transfer and basic fabrication techniques, the paper reviews and discusses drug delivery devices for cellular, tissue and organism levels. At the cellular level, a concentration gradient generator integrated with a cell culture platform is the main drug delivery scheme of interest. At the tissue level, the synthesis of smart particles as drug carriers using lab-on-a-chip technology is the main focus of recent developments. At the organism level, microneedles and implantable devices with fluid-handling components are the main drug delivery systems. For drug delivery to a small organism that can fit into a microchip, devices similar to those of cellular level can be used.