Introduction

Securing organ donors for surgeries presents a challenging process marked by three main obstacles: failed donor registrations, the need  for precise donor matches, and the overwhelming demand for  donors. These hurdles often stem from various issues such as medical complications, religious beliefs, and the complexity of finding compatible matches based on factors like ethnicity and transportation logistics. The pressing demand for organs is underscored by the alarming statistic that a new individual is added to the national transplant waiting list in the United States every 10 minutes.  Addressing these challenges, this study delves into the development of bioink, utilizing biocompatible materials like gelatin, glucose, and starch. By exploring the composition of bioinks, researchers can make subtle adjustments to tailor the hardness and flexibility of the  solution once it cools and sets. Trials have revealed that a 1:1 ratio of tapioca starch to cornstarch produces a bioink with a harder, less adhesive finish, suitable for skin models, while softer variants are  ideal for delicate tissues like organs. Moreover, advancements in this  area could pave the way for 3D printing organs, offering potential  solutions to the shortage of donor organs.

3D Bioprinting

In the realm of tissue engineering and regenerative medicine, 3D bioprinting emerges as a crucial technology for simulating native organs and tissues. This innovative approach involves layering biomaterials to replicate the complex structures of tissues, offering numerous advantages such as personalized patient-specific designs, high precision, and cost-effectiveness. The expedited  fabrication of intricate structures further enhances the appeal of 3D  bioprinting in biomedical applications. As researchers continue to  delve into this technology, its potential to revolutionize healthcare by offering bespoke solutions tailored to individual patients becomes increasingly evident.

Bio Ink Solution

Base Formula.

Originally, using Figure 1 (look at the image section) as a base formula for the start of the bio ink  experimentation. As it was a formula that required easily accessible  materials, it served as an understandable base formula which will be the  first formula prototype. By using this formula, the result was in a tender, adhesive gelatin that had a similar appearance to fat. This result however, was too soft and the bio ink that was desired should be harder and less flexible. This desired texture was so that the bio ink solution  could be extruded to be shaped as 3D filament for 3D printers. 

Final Formula (look at image section, figure 2)

After further research on how to create a harder bio ink once it dries, incorporating the formula to create biodegradable plastic allowed for  the desired texture. By using a mixture (ratio 1:1) of tapioca starch and cornstarch, the result after swiping a layer on aluminum foil, the  texture was smoother, harder, and became non adhesive. Meanwhile using only rice flour or cornstarch, the result of the solution was a flexible, softer, and adhesive on surfaces, unlike the result of the 1:1  ratio of tapioca starch to cornstarch.

Creation Process of Bio Ink Solution

Using the final formula as the foundation for the bioink solution, this experiment investigates the qualitative differences resulting from varying  starch components. One variant employs rice flour exclusively, while the other utilizes a 1:1 ratio of cornstarch and tapioca starch. Following the  assembly of materials including gelatin, glycerine, distilled water, tapioca starch, corn starch, rice flour, and citric acid, measurements are  conducted according to the formula depicted in Fig. 2 to prepare the two versions of the bioink solution. Subsequently, all measured ingredients  are combined in a 250ml beaker equipped with a magnetic stirrer, with the heat set to 280 ℃ and the rotating magnetic field to 220 rpm. The  temperature is gradually increased to 45-50℃ to facilitate melting of the starch, gelatin, and citric acid. Once thoroughly combined, the  consistency of the two bioink solutions is assessed using a glass rod under the prescribed heat and magnetic field conditions before transferring  the solution onto aluminum foil and smoothing it evenly using the glass rod. 

((look at image section to see detailed process))

3D Printed Components

The piston mechanism will allow for the bio ink solution  to be dispelled in a consistent rate rather than relying on  gravity to expel the solution as it would result in an  inconsistent rate which is not ideal for 3D printing and  may disrupt the finished 3D printed object. The Nema  17 Pancake Stepper Motor will rotate the gear placed  on top of it which will result in rotating the gear  connected to it. The rotation of this gear will then allow  the metal rod to move downwards, creating a piston mechanism that can push the bio ink solution down at consistent rate. 

The container will hold the bio ink solution; this approach  was inspired by a chocolate 3D printer that was made by  Cocoa Press. As the chocolate cannot be extruded into  chocolate filaments, modifications have to be made in order to be able to use the chocolate for 3D printing. This is similar to the bio ink solution that is created. Despite being a viscose solution, it does not harden quickly enough like PLA which is a component of 3D filaments (Team Xometry). Hence, adapting the contraption that is being used for the chocolate 3D printer would be essential for the current bio ink solution.

Conclusion, Application and Future Outlook

The future of this bio ink solution is the testing of its biocompatibility with stem cells to create  structures for organs and to create skin; testing the water resistance of the dried sample of  the bio ink solution; and the extruding test should be conducted to see the possibility of  creating bio ink filaments similar to the existing 3D filaments. By experimenting further with  these testing in mind, the application of the bio ink solution and extruder into a purchasable  product for others would be able to contribute to the field of study of 3D bioprinting. The  Distilled Water  potential of this research may impact the future of regenerative medicine as it opens the  possibility to create a bio ink solution that can serve as the base formula for organ structures.  By creating the extruder for the bio ink, this can help in manufacturing the bio ink filaments making them more easily transported and sold for companies, labs, and hospitals that are  experimenting in this bioprinting. Furthermore, connecting with universities and hospitals may also be possible after furthering the research on the 3 aspects mentioned (testing biocompability with stem cells to create structures for the water resistance of the dried sample of the bio ink solution; and the extruding test) will allow for this research on bio ink to become a noticeable scientific advancement.