Chemoselective Liposome Fusion for Cell-Surface and Tissue Engineering Applications

Proper cell-cell communication through physical contact is crucial for a range of fundamental biological processes including, cell proliferation, migration, differentiation, and apoptosis and for the correct function of organs and other multi-cellular tissues. The spatial and temporal arrangements of these cellular interactions in vivo are dynamic and lead to higher-order function that is extremely difficult to recapitulate in vitro. The development of 3-dimensional (3D), in vitro model systems to investigate these complex, in vivo interconnectivities would generate novel methods to study the biochemical signaling of these processes, as well as provide platforms for tissue engineering technologies. Herein, we develop and employ a strategy to induce specific and stable cell-cell contacts in 3D through chemoselective cell-surface engineering based on liposome delivery and fusion to display bio-orthogonal functional groups from cell membranes. This strategy uses liposome fusion for the delivery of ketone or oxyamine groups to different populations of cells for subsequent cell assembly via oxime ligation. We demonstrate how this method can be used for several applications including, the delivery of reagents to cells for fluorescent labeling, the formation of small, 3D spheroid cell assemblies, and the generation of large and dense, 3D multi-layered tissue-like structures. We were also able to create dynamic and switchable cell tissue assemblies through chemoselective conjugation and release chemistry. Cell membranes are decorated with a range of molecules that can be released in vitro for subsequent rounds of molecular conjugation and release. Each step to modify the cell surface: activation, conjugation, release, and regeneration can be monitored and modulated by non-invasive, label-free analytical techniques. Additionally, we also develop and demonstrate a novel liposome fusion based delivery strategy to incorporate a unique bio-orthogonal lipid that has the dual ability to serve as a receptor for chemoselective cell surface tailoring and as a reporter to track cell behavior

Synthetic and structural investigation of ZnO nano-rods, hydrothermally grown over Au coated optical fiber for evanescent field-based detection of aqueous ammonia

We present the fabrication of modified clad optical fiber coated with ZnO nanorod over Au thin film to be served as ammonia gas sensor. The deposited material ZnO synthesized by hydrothermal process and modified clad fiber is coated by Autoclave technique. The as-synthesized materials are characterized by XRD, XPS, FTIR, Raman spectra and its hexagonal nanorods morphology was checked by FESEM. The ZnO coated over Au thin film fiber is found to be a good candidate towards ammonia sensing. The developed sesnor exihibted sensitivity (%) ~ 0.638 of ammonia gas at room temperature

Remote Control of Tissue Interactions via Engineered Photo-switchable Cell Surfaces

We report a general cell surface molecular engineering strategy via liposome fusion delivery to create a dual photo-active and bio-orthogonal cell surface for remote controlled spatial and temporal manipulation of microtissue assembly and disassembly. Cell surface tailoring of chemoselective functional groups was achieved by a liposome fusion delivery method and quantified by flow cytometry and characterized by a new cell surface lipid pull down mass spectrometry strategy. Dynamic co-culture spheroid tissue assembly in solution and co-culture tissue multilayer assembly on materials was demonstrated by an intercellular photo-oxime ligation that could be remotely cleaved and disassembled on demand. Spatial and temporal control of microtissue structures containing multiple cell types was demonstrated by the generation of patterned multilayers for controlling stem cell differentiation. Remote control of cell interactions via cell surface engineering that allows for real-time manipulation of tissue dynamics may provide tools with the scope to answer fundamental questions of cell communication and initiate new biotechnologies ranging from imaging probes to drug delivery vehicles to regenerative medicine, inexpensive bioreactor technology and tissue engineering therapies

Detection of Ammonia Gas Molecules in Aqueous Medium by Using Nanostructured Ag-Doped ZnO Thin Layer Deposited on Modified Clad Optical Fiber

The synthesis of Ag-doped ZnO nanorod employing hydrothermal process over modified cladd optical fiber is reported. The developed material is characterized using X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and Brunauer-Emmett-Teller (BET)analysis to evaluate the morphology and the nature of nanorod formed. The initial performance of the coated modified clad optical fiber toward detection of ammonia gas in aqueous solution is also presented. The sensing performance revealed that the developed material possess improved sensitivity toward ammonia gas at room temperature compared to Ag doped nanowires containing optical fiber sensor

Chemoselective liposome fusion for cell-surface and tissue engineering applications

Proper cell-cell communication through physical contact is crucial for a range of fundamental biological processes including, cell proliferation, migration, differentiation, and apoptosis and for the correct function of organs and other multi-cellular tissues. The spatial and temporal arrangements of these cellular interactions in vivo are dynamic and lead to higher-order function that is extremely difficult to recapitulate in vitro. The development of 3-dimensional (3D), in vitro model systems to investigate these complex, in vivo interconnectivities would generate novel methods to study the biochemical signaling of these processes, as well as provide platforms for tissue engineering technologies. Herein, we develop and employ a strategy to induce specific and stable cell-cell contacts in 3D through chemoselective cell-surface engineering based on liposome delivery and fusion to display bio-orthogonal functional groups from cell membranes. This strategy uses liposome fusion for the delivery of ketone or oxyamine groups to different populations of cells for subsequent cell assembly via oxime ligation. We demonstrate how this method can be used for several applications including, the delivery of reagents to cells for fluorescent labeling, the formation of small, 3D spheroid cell assemblies, and the generation of large and dense, 3D multi-layered tissue-like structures. We were also able to create dynamic and switchable cell tissue assemblies through chemoselective conjugation and release chemistry. Cell membranes are decorated with a range of molecules that can be released in vitro for subsequent rounds of molecular conjugation and release. Each step to modify the cell surface: activation, conjugation, release, and regeneration can be monitored and modulated by non-invasive, label-free analytical techniques. Additionally, we also develop and demonstrate a novel liposome fusion based delivery strategy to incorporate a unique bio-orthogonal lipid that has the dual ability to serve as a receptor for chemoselective cell surface tailoring and as a reporter to track cell behavior

The impact of the COVID-19 pandemic on health-care delivery system for other diseases and antimicrobial resistance threat in India

India's health-care delivery is challenged with different inequalities and theelivery is challenged with different inequalities and the dual burden of communicable and noncommunicable diseases. Lockdown posed negative effects on the growth and economy of the country; simultaneously, some positive effects, like increased health consciousness and adoption of hygienic practices, were also there. Health-care delivery system faced tremendous challenges in diagnostics, therapeutics, infrastructure for inpatient care, and protection of health-care manpower. During this period, people chose to self medicate which in turn increased the threat of emergence of antimicrobial resistance. Due to shifting priority to COVID from other diseases, resources were shifted to COVID, affecting the management of other acute and chronic diseases. The launching of COVID-19 vaccination campaign showed some hope. However, despite the vaccination drive, strengthening infrastructure, and surveillance system, the devastating second wave could not be avoided due to the conglomeration of the crowd for pilgrimage, election campaign, and tourism in an unrestricted manner. It may be concluded that the fourth wave may be short lasting due to increased herd immunity

Optical Properties of Chromium and Erbium Co-Doped Alumina-Germania-Calcia-Yttria-Silica Based Fiber

We report the fabrication details and optical characterization of novel Erbium (Er) and Chromium (Cr) co-doped alumina-germania-calcia-yttria-silica fiber. Co-doping with Er and Cr is chosen as potentially promising for enhancing the fiber's fluorescent and amplifying potential in the near-infrared (NIR) region at `resonant' (viz. into Er band absorption maximum, @976 nm) and `non-resonant' (viz. off Er band while into Cr broad absorption band, @905/1064 nm) excitations. Our results reveal strong coupling, at both kinds of excitation, of Er- and Cr- subsystems in the fiber. This effect is justified by the presence of pronounced 1.5-1.6 mu m emission, characteristic to Er ions, at 905/1064 nm excitations and, at 976-nm excitation, by notable spectral broadening of the fiber's NIR fluorescence and gain, comprising the lines inherent to Er3+ (1.5-1.6 mu m) and Cr3+/Cr4+ (1.15-1.45 mu m), as compared to purely Er-doped silicate fiber, exemplified here by commercial `L20' (Er20-4/125) and `L40' (Er40-4/125) fibers