MICROFLUIDIC DEVICES AS A TOOL FOR DRUG DELIVERY AND DIAGNOSIS: A REVIEW Review Article ISHA SHARMA, MONIKA THAKUR, SHAVETA SINGH, ASTHA TRIPATHI * Department of Applied Sciences and Biotechnology Shoolini University, Vill-Bhajhol Solan, Himachal Pradesh, India, 173229 Email: asthatripathi4u@gmail.com Received: 20 Oct 2020, Revised and Accepted: 26 Nov 2020 ABSTRACT Microfluidic devices are a good example of the collaboration of chemical, biological, and engineering sciences. Microfluidic devices emerge as an in fluent technology which provides an alternative to conventional laboratory methods. These devices are employed for the precise handling and transport precise quantities of drugs without toxicity. This system is emerging as a promising platform for designing advanced drug delivery systems and analysis of biological phenomena on miniature devices for easy diagnosis. Microfluidics enables the fabrication of drug carriers with controlled geometry and specific target sites. Microfluidic devices are also used for the diagnosis of cancer circulating tumor cells. In the current review, different microfluidic drug delivery systems and diagnostic devices have described. Keywords: Microfluidic drug delivery system, Circulating tumor cells, Cancer diagnosis, Lab on chip © 2021 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/) DOI: http://dx.doi.org/10.22159/ijap.2021v13i1.39032. Journal homepage: https://innovareacademics.in/journals/index.php/ijap INTRODUCTION Microfluidic devices are an excellent tool for drug delivery and evaluation of drug effectiveness at the cellular level. Microfluidics devices consist of a micro-electro-mechanical system. In recent years the microfluidic devices are emerging as an important tool for cancer detection. These devices are used to analyze the fluids which are present in the micrometer-sized channels. There are many types of microfluidic devices that have been developed [1]. Cancer is also known as a malignant neoplasm, which includes a broad group of diseases having unregulated cell growth. In this disease, there is uncontrollable division and growth, which causes the formation of malignant tumors. This malignant tumor can invade multiple organs and spread to the whole body. The leading cause of death throughout the world is due to cancer [2]. At present many treatment options are available for cancer, which includes surgery, chemotherapy, radiation therapy, and palliative care. All the above treatments depend upon the type, location, and grade of cancer [3]. These treatments had disadvantages as these are very expensive and had various side effects. Circulating tumor cells (CTCs) are rare cancer circulating in the blood vessels in cancer metastasis. The detection of CTCs provides a rapid and less painful diagnosis method as compared to tissue biopsy. This method is a very good alternative to the previous invasive biopsy. It is also termed as liquid biopsy as only blood is withdrawn for cancer detection [4]. Rapid research is going on to develop microfluidic devices for drug delivery and detection of CTCs. The most widely accepted devices are chromatography, quantum dots, surface plasmon resonance, amperometric based sensing, and nuclear magnetic resonance [5]. In this review, types of microfluidic devices, drug delivery, and screening have been described. The review is based on data obtained from Pubmed (http://www.ncbi.nlm.gov//pubmed) and Google scholar with preference given to the data obtained during the last 10 y. The research items were varied. The main research terms were microfluidic devices, microfluidic drug delivery system, microscale channels, microneedles for drug delivery, circulating tumor cells, diagnosis of CTCs by the microfluidic system, lab-on- chip and various combinations of these trems. Microfluidic drug delivery system Drug delivery using microfluidic devices on unhealthy tissues is done with high precision and a localized manner. Drug delivery is done by small particles in the form of bio capsules, microparticles, and nanoparticles. Another drug delivery system used is the microneedles. Microfluidic devices have many advantages over the conventional delivery system, such as precise target delivery, controlled release, precise dosage, and multiple dosages. These devices are used for the direct drug delivery and fabrication of drug carriers. The side effects of another system that are overcome in this system are toxicity, inflammation, and wastage. Microfluidics drug systems are used for peptides, proteins, and DNA based drugs to the target sites. This method also protects drugs from enzymatic degradation and the immune response of the host body [6]. Fabrication of drug carriers The drugs for proper action should reach the target organ without any damage. It should be protected from stomach acid, enzymes, and immune cells. The drug carriers of different polymer materials are used as drug carriers [7]. Now day's microfluidic devices are used for the fabrication of drug carriers by mixing different particles. The drug carrier should be biodegradable, biocompatible, and nontoxic. The polymers used as drug carriers are made more suitable by modifying using microfluidic devices [8]. This system helps to fabricate uniform particles and thus provides better bioavailability and controlled release of drugs. A microfluidic device fabricates to produce nanoparticles from PLGA-PEG and PLGA. The Microfluidic system also enhances the ratio of drug load into the particle and encapsulation of multiple drugs into one particle by mixing particles of different nature and phases [9]. Microfluidic devices can fabricate drug carriers from nano to micro size and also maintain the uniform size. The self-assembled microfluidic fabrication is done by simple micromixer, hydrodynamic flow focusing and staggered herringbone micromixer (fig. 1-3). In hydrodynamic flow, a core of carrier solution, which consists of a surfactant mixer, is focused on the microchannel by surrounding streams of the miscible buffer. The microfluidic devices can also control the uniformity of the drugs carrier by geometry, flow rates, and diffusion coefficient of miscible streams. Micromixers are of two types active and passive depends upon the force applied. In an active mixer, the external source is used to mix two fluids of different phases. The forces like acoustic and ultrasonic waves, magnetic particles are used to exert force for mixing the particles. In the passive type, mixing depends upon the hydrodynamic flow of fluids no external force is applied as shown in fig. 1 [10]. Staggered herringbone mixer depends upon the chaotic advection. It consists of repeated patterns of grooves on the bottom surface of the microchannel. The grooves internally contain two channels of different lengths (one longer and another shorter) which are connected at an angle of 45 ° as shown in fig. 2. Helical motion is created to move the fluid inside the channel by the grooves. This method provides high efficiency of mixing drug carriers [11]. International Journal of Applied Pharmaceutics ISSN- 0975-7058 Vol 13, Issue 1, 2021