Biology subjects

Gandhi, P.

Publications and source records attributed to Gandhi, P..

4 recordsLinked to original sources

bioRxiv2026

A Versatile Microfluidic Device for High-throughput Combinatorial Drug Screening

Combination therapies can improve anticancer efficacy, but identifying effective drug pairs and dose combinations requires systematic exploration of multidimensional concentration spaces. Here, we extend a diffusion-driven, flowless microfluidic concentration gradient generator (CGG) to enable quantitative combinatorial drug screening without external pumps or continuous flow. The platform comprises a 5 x 5 array of interconnected culture nodes coupled to four peripheral reservoirs, in which overlapping diffusion fields generate spatially defined single- and multidrug exposures. Computational modelling was used to assign local drug concentrations to individual nodes, enabling direct correlation of the predicted exposure landscape with cellular response. Using MCF-7 breast cancer cells and 5-fluorouracil (5-FU) and doxorubicin (DOX) as model therapeutics, the platform resolved concentration-dependent single-agent responses, yielding IC50 values of 3.46 M for 5-FU and 1.22 M for DOX. Combinatorial loading generated 25 spatially defined 5-FU-DOX concentration pairs within a single device, which were resolved into two-dimensional concentration-response landscapes. Bliss independence analysis revealed concentration-specific drug interactions, with synergy predominating at low-to-intermediate concentrations and a transition towards additive and antagonistic responses at higher exposures. These findings establish a pump-free microfluidic strategy that integrates computational concentration mapping with spatially resolved pharmacological analysis to identify effective drug-combination windows within a single platform.

cancer biology↗

bioRxiv2022

Lithography-less, frugal and long-term diffusion-based static gradient generating microfluidic device for high-throughput drug testing

Drug testing is a vital step in identification of the potential efficacy of any new/existing drug and/or combinations of drugs. The conventional methods of testing the efficacy of new drugs using multi-well plates are time consuming, prone to evaporation loss and manual error. Microfluidic devices with automated generation of concentration gradient provide a promising alternative. The implementation of such microfluidic devices is still limited owing to the additional expertise and facilities required to fabricate and run these devices. Conventional microfluidic devices also need pumps, tubings, valves, and other accessories, making them bulky and nonportable. To address these problems, we have developed a method for fabricating microfluidic structures using a nonconventional technique by exploiting the Saffman-Taylor instability in lifted Hele-Shaw cell. Multi-channel structure molds with varying dimensions were fabricated by shaping ceramic polymer slurry and retaining the shape. Further using the mold thus made, polydimethyl siloxane (PDMS) devices offering static, stable, diffusion-based gradient were casted using soft lithography. We have demonstrated with COMSOL simulation, as well as using Fluorescein isothiocyanate (FITC), a fluorescent dye, that the concentration gradient can be generated in this device, which remains stable for at least 5 days. Using this multichannel device, in vitro drug efficacy was validated with two drugs namely-Temozolomide (TMZ) and Curcumin, one FDA approved and one under research, on glioblastoma cells (U87MG). The resulting IC50 values were consistent with those reported in literature. We have also demonstrated the possibility of conducting molecular assays post-drug testing in the device by microtubule staining after curcumin treatment on cervical cancer cells (HeLa). In summary, we have demonstrated a i) user-friendly, ii) portable, static drug testing platform that iii) does not require further accessories and can create iv) a stable gradient for long duration. Such a device can reduce the time, manual errors, fabrication and running expenditure, and resources to a great extent in drug testing. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/505813v1_ufig1.gif" ALT="Figure 1"> View larger version (79K): org.highwire.dtl.DTLVardef@e1f648org.highwire.dtl.DTLVardef@f029d7org.highwire.dtl.DTLVardef@14afd68org.highwire.dtl.DTLVardef@42b888_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2022

Scalable large-area mesh-structured microfluidic gradient generator for drug testing applications

Microfluidic concentration gradient generators are useful in drug testing. drug screening, and other cellular applications to avoid manual errors, save time, and labor. However, expensive fabrication techniques make such devices prohibitively costly. Here, in the present work, we developed a microfluidic concentration gradient generator (CGG) using a recently proposed non-conventional photolithography-less method. In this method, ceramic suspension fluid was shaped into a square mesh by controlling Saffman Taylor instability in a Multiport Lifted Hele-Shaw Cell (MLHSC). Using the shaped ceramic structure as template, the microfluidic concentration gradient generator (CGG) was prepared by soft lithography. The concentration gradient was characterized and effect of the flow rates were studied usingCOMSOL simulations. The simulation result was further validated by creating fluorescein dye (Fluorescein isothiocanate, FITC) gradient in the fabricated CGG. To demonstrate the use of this device for drug testing, we created various concentrations of an anticancer drug - curcumin - using the device and determined its inhibitory concentration on cervical cancer cell-line HeLa. We found that the IC50 of curcumin for HeLa to be 28.6 {+/-} 6.1 M which matched well with the conventional muti-well drug testing method (34.9 {+/-} 1.7 M). This method of CGG fabrication has multiple advantages over conventional photolithography such as: i) the channel layout and inlet-outlet arrangements can be changed by simply wiping the ceramic fluid before it solidifies, (ii) it is cost effective, (iii) large area patterning is easily achievable, and (iv) the method is scalable. This technique can be utilised to achieve broad range of concentration gradient to be used for various biological and non-biological applications. Table of Content O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=99 SRC="FIGDIR/small/500002v2_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@d0bb65org.highwire.dtl.DTLVardef@1bef09dorg.highwire.dtl.DTLVardef@a6ebe8org.highwire.dtl.DTLVardef@c9dd17_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2020

Integrated role of microRNA-30e-5p through targeting negative regulators of innate immune pathways during HBV infection and SLE

Precise regulation of innate immunity is crucial for the development of appropriate host immunity against microbial infections and the maintenance of immune homeostasis. The microRNAs are small non-coding RNA, post-transcriptional regulator of multiple genes and act as a rheostat for protein expression. Here, we identified microRNA(miR)-30e-5p (miR-30e) induced by the hepatitis B virus (HBV) and other viruses that act as a master regulator for innate immune responses. Moreover, pegylated type I interferons treatment to HBV patients for viral reduction also reduces the miRNA. Additionally, we have also shown the immuno-pathological effects of miR-30e in systemic lupus erythematous (SLE) patients and SLE mouse model. Mechanistically, the miR-30e targets multiple negative regulators namely TRIM38, TANK, ATG5, ATG12, BECN1, SOCS1, SOCS3 of innate immune signaling pathways and enhances innate immune responses. Furthermore, sequestering of endogenous miR-30e in PBMCs of SLE patients and SLE mouse model respectively by the introduction of antagomir and locked nucleic acid based inhibitor significantly reduces type I interferon and pro-inflammatory cytokines. Collectively, our study demonstrates the novel role of miR-30e in innate immunity and its prognostic and therapeutic potential in infectious and autoimmune diseases.

immunology↗