Jugal K. Gupta

Bio: Jugal K. Gupta is an academic researcher from University of Wisconsin-Madison. The author has contributed to research in topics: Liquid crystal & Thermotropic crystal. The author has an hindex of 12, co-authored 14 publications receiving 913 citations. Previous affiliations of Jugal K. Gupta include Wisconsin Alumni Research Foundation.

Liquid Crystal Emulsions as the Basis of Biological Sensors for the Optical Detection of Bacteria and Viruses

Abstract: A versatile sensing method based on monodisperse liquid crystal (LC) emulsion droplets detects and distinguishes between different types of bacteria (Gram +ve and −ve) and viruses (enveloped and non-enveloped). LCs of 4-cyano-4'-pentylbiphenyl transition from a bipolar to radial configuration when in contact with Gram −ve bacteria (E. coli) and lipid-enveloped viruses (A/NWS/Tokyo/67). This transition is consistent with the transfer of lipid from the organisms to the interfaces of the micrometer-sized LC droplets. In contrast, a transition to the radial configuration is not observed in the presence of Gram +ve bacteria (Bacillus subtilis and Micrococcus luteus) and non-enveloped viruses (M13 helper phage). The LC droplets can detect small numbers of E. coli bacteria (1–5) and low concentrations (104 pfu mL−1) of A/NWS/Tokyo/67 virus. Monodisperse LC emulsions incubated with phosholipid liposomes (similar to the E. coli cell wall lipid) reveal that the orientational change is triggered at an area per lipid molecule of ∼46 A2 on an LC droplet (∼1.6 × 108 lipid molecules per droplet). This approach represents a novel means to sense and differentiate between types of bacteria and viruses based on their cell-wall/envelope structure, paving the way for the development of a new class of LC microdroplet-based biological sensors.

Size‐Dependent Ordering of Liquid Crystals Observed in Polymeric Capsules with Micrometer and Smaller Diameters

Abstract: Made to order: Aqueous dispersions of polymer-encapsulated liquid crystal (LC) droplets were synthesized with precise interfacial chemistry and sizes in the micrometer-to-sub-micrometer range. Size-dependent changes in LC ordering could be observed. Study of the competition between size and interfacial chemistry on LC ordering enables size-dependent properties of LC droplets to be exploited in applications such as photonics and sensing.

Characterization of adsorbate-induced ordering transitions of liquid crystals within monodisperse droplets.

Abstract: The ordering of liquid crystals (LCs) within micrometer-sized droplets is known to depend strongly on the presence of interfacial adsorbates, although the exact sequence of ordered equilibrium states that accompany a change in interfacial anchoring from tangential to perpendicular has not been established. In this paper, we report use of a methodology that permits the preparation of monodisperse LC droplets in aqueous phases to investigate ordering transitions in the LC droplets that accompany the adsorption of amphiphiles at the aqueous-LC droplet interface. By using an amphiphile that undergoes reversible adsorption at the aqueous-LC interface (sodium dodecylsulfate, SDS), we identified six distinct topologically ordered states of the LC droplets as a function of increasing concentration of SDS. We exploited the reversible adsorption of the SDS to LC droplets with diameters of 8.0+/-0.2 microm to confirm that these topological states are equilibrium ones. We also exposed LC droplets to a continuous gradient in concentration of SDS to document the continuous transitions between topological states and to confirm the absence of additional, intermediate topological states. The formation of the LC droplets as aqueous dispersions also enabled an investigation of ordering transitions in LC droplets driven by biomolecular interactions. Surprisingly, enzymatic hydrolysis of the phospholipid L-dipalmitoyl phosphatidylcholine (L-DLPC) by phospholipase A2 at the interfaces of the LC droplets was observed to trigger the same progression of topologically ordered states of the LC as was observed with SDS. Overall, the results presented in this paper resolve prior conflicting data in the literature by providing an unambiguous set of observations regarding topologically ordered states encountered in LC droplets. This paper provides a data set against which future theories and simulations of LCs can be compared to develop a fundamental understanding of the competition between volumetric and interfacial effects in droplets. The results also suggest that topological ordering transitions in LC droplets can be exploited to report interfacial enzymatic reactions.

Influence of simple electrolytes on the orientational ordering of thermotropic liquid crystals at aqueous interfaces.

Abstract: We report orientational anchoring transitions at aqueous interfaces of a water-immiscible, thermotropic liquid crystal (LC; nematic phase of 4′-pentyl-4-cyanobiphenyl (5CB)) that are induced by changes in pH and the addition of simple electrolytes (NaCl) to the aqueous phase. Whereas measurements of the zeta potential on the aqueous side of the interface of LC-in-water emulsions prepared with 5CB confirm pH-dependent formation of an electrical double layer extending into the aqueous phase, quantification of the orientational ordering of the LC leads to the proposition that an electrical double layer is also formed on the LC-side of the interface with an internal electric field that drives the LC anchoring transition. Further support for this conclusion is obtained from measurements of the dependence of LC ordering on pH and ionic strength, as well as a simple model based on the Poisson–Boltzmann equation from which we calculate the contribution of an electrical double layer to the orientational anchoring ...

Polymeric Multilayer Capsules in Drug Delivery

Abstract: Recent advances in medicine and biotechnology have prompted the need to develop nanoengineered delivery systems that can encapsulate a wide variety of novel therapeutics such as proteins, chemotherapeutics, and nucleic acids. Moreover, these delivery systems should be "intelligent", such that they can deliver their payload at a well-defined time, place, or after a specific stimulus. Polymeric multilayer capsules, made by layer-by-layer (LbL) coating of a sacrificial template followed by dissolution of the template, allow the design of microcapsules in aqueous conditions by using simple building blocks and assembly procedures, and provide a previously unmet control over the functionality of the microcapsules. Polymeric multilayer capsules have recently received increased interest from the life science community, and many interesting systems have appeared in the literature with biodegradable components and biospecific functionalities. In this Review we give an overview of the recent breakthroughs in their application for drug delivery.

Systems and methods for multi-analysis

Abstract: Systems and methods are provided for sample processing. A device may be provided, capable of receiving the sample, and performing one or more of a sample preparation, sample assay, and detection step. The device may be capable of performing multiple assays. The device may comprise one or more modules that may be capable of performing one or more of a sample preparation, sample assay, and detection step. The device may be capable of performing the steps using a small volume of sample.

Endotoxin-Induced Structural Transformations in Liquid Crystalline Droplets

Abstract: The ordering of liquid crystals (LCs) is known to be influenced by surfaces and contaminants Here, we report that picogram per milliliter concentrations of endotoxin in water trigger ordering transitions in micrometer-size LC droplets The ordering transitions, which occur at surface concentrations of endotoxin that are less than 10−5 Langmuir, are not due to adsorbate-induced changes in the interfacial energy of the LC The sensitivity of the LC to endotoxin was measured to change by six orders of magnitude with the geometry of the LC (droplet versus slab), supporting the hypothesis that interactions of endotoxin with topological defects in the LC mediate the response of the droplets The LC ordering transitions depend strongly on glycophospholipid structure and provide new designs for responsive soft matter

Layer‐By‐Layer‐Assembled Capsules and Films for Therapeutic Delivery

Abstract: Polymeric materials formed via layer-by-layer (LbL) assembly have promise for use as drug delivery vehicles. These multilayered materials, both as capsules and thin fi lms, can encapsulate a high payload of toxic or sensitive drugs, and can be readily engineered and functionalized with specific properties. This review highlights important and recent studies that advance the use of LbL-assembled materials as therapeutic devices. It also seeks to identify areas that require additional investigation for future development of the field. A variety of drug-loading methods and delivery routes are discussed. The biological barriers to successful delivery are identified, and possible solutions to these problems are discussed. Finally, state-of-the-art degradation and cargo release mechanisms are also presented.