High-Throughput Dispensing of Viscous Solutions for Biomedical Applications

Abstract

Cells cultured in three-dimensional scaffolds express a phenotype closer to in vivo cells than cells cultured in two-dimensional containers. Natural polymers are suitable materials to make three-dimensional scaffolds to develop disease models for high-throughput drug screening owing to their excellent biocompatibility. However, natural polymer solutions have a range of viscosities, and none of the currently available liquid dispensers are capable of dispensing highly viscous polymer solutions. Here, we report the development of an automated scaffold dispensing system for rapid, reliable, and homogeneous creation of scaffolds in well-plate formats. We employ computer-controlled solenoid valves to regulate air pressure impinging upon a syringe barrel filled with scaffold solution to be dispensed. Automated dispensing of scaffold solution is achieved via a programmable software interface that coordinates solution extrusion and the movement of a dispensing head. We show that our pneumatically actuated dispensing system can evenly distribute high-viscosity, chitosan-based polymer solutions into 96- and 384-well plates to yield highly uniform three-dimensional scaffolds after lyophilization. We provide a proof-of-concept demonstration of high-throughput drug screening by culturing glioblastoma cells in scaffolds and exposing them to temozolomide. This work introduces a device that can hasten the creation of three-dimensional cell scaffolds and their application to high-throughput testing.

3D Porous Scaffold-Based High-Throughput Platform for Cancer Drug Screening

“…The HTS platform was manufactured by computer-aided rapid dispensing system of the CHA polymer solution and followed by freeze-drying to generate a 3D porous structure, as shown in Figure 1 . The design and setup of the dispenser was presented in a previous work of our lab, where a fully automated and well-controlled dispensing system of viscous polymer solution into 96- and 384-well plates could be achieved [ 18 ]. As shown in Figure S1 , the CHA scaffolds were uniformly cast as 2 mm discs at the bottom of 96-well plates.…”

“…Two solutions were then combined and mixed using a Thinky mixer (ARM-300, Thinky, Laguna Hills, CA, USA) at 2000 rpm for three minutes, and further mixed in a blender for ten minutes to ensure a homogeneous polymer mixture. The polymer mixture was then centrifuged at 2000 rpm for 30 min to remove air bubbles and cast into 96-well tissue culture plates using a self-designed computer-aided automated scaffold dispenser [ 18 ]. The dispensing pressure and dispensing time were controlled to achieve a dispensing of 65 μL/well in order to reach a thickness of around 2 mm.…”

“…However, there are obstacles still holding the translation of such scaffold-based HTS platforms back, from bench-top research to human clinical trials. First, the polymer solution of chitosan and HA is usually highly viscous and difficult to handle, hampering the large-batch production of CHA scaffolds [ 18 ]. Hence, it is vital to establish a scalable manufacturing strategy that can accommodate the 3D CHA scaffold to a HTS platform.…”

Rapid fabrication and screening of tailored functional 3D biomaterials: Validation in bone tissue repair – Part II

“…In the present study we present a novel method to synthesize the polymer scaffolds in a multi-well format. This reduces artifacts introduced during transfer of a preformed polymer scaffold onto a well plate using dispensing techniques [23]. Such a high throughput technique presented in this current study provides an advantage over other methods such as 3D printing as it facilitates a thorough investigation of cell behaviour in a three-dimensional environment with highly controlled porosity, often lacking in 3D printing techniques [7,24].…”

Validation of a Novel Electromagnetically Operated Free Flow Liquid Dispensing System

“…Automatic and semi-automatic liquid dispensers employing various actuating methods have been developed such as thermal-bubble, piezoelectric, pneumatic, and solenoid actuation. (1)(2)(3)(4)(5). These instruments aim to provide a rapid, flexible, and convenient method to dispense different types of liquids with high reliability and accuracy in a wide range of volumes.…”