Wide accessibility and a broad range of applications have made 3D-printers a commonplace tool in the science community. From tier-one research institutions to community public libraries and high schools, 3D-printers are being used to enrich STEM education through a variety of learning techniques and experiences. Reports of 3D-printed models for improved visualization of chemical phenomena, as well as the educational use of 3D-printed laboratory devices, are rapidly increasing. The objective of this review is to provide a resource for educators interested in incorporating 3D-printing into their chemistry classrooms by evaluating recent peer-reviewed reports that used this technology to enhance chemistry education.

People with type 1 diabetes (T1D) require exogenous administration of insulin, which stimulates the translocation of the GLUT4 glucose transporter to cell membranes. However, most bloodstream cells contain GLUT1 and are not directly affected by insulin. Here, we report that C-peptide, the 31-amino acid peptide secreted in equal amounts with insulin in vivo, is part of a 3-component complex that affects red blood cell (RBC) membranes. Multiple techniques were used to demonstrate saturable and specific C-peptide binding to RBCs when delivered as part of a complex with albumin. Importantly, when the complex also included Zn2+, a significant increase in cell membrane GLUT1 was measured, thus providing a cellular effect similar to insulin, but on a transporter on which insulin has no effect.

The pancreatic β‐cells of healthy individuals secrete insulin and C‐peptide, a 31‐amino acid peptide, in a 1:1 mole ratio. However, the β‐cells of people with type 1 diabetes (T1D) are damaged or destroyed. Therefore, exogenous insulin is required for people with T1D to survive. Even with regular insulin treatments, patients develop complications such as retinopathy, neuropathy, and nephropathy. Research from our group demonstrates that C‐peptide increases microvascular blood flow, therefore, it could be a useful tool to decrease these complications due to poor blood flow. However, the unknown C‐peptide receptor and mechanism has been a major roadblock in utilizing C‐peptide as a therapeutic. Utilizing ELISA, our group has demonstrated that approximately 1,800 C‐peptide molecules bind per red blood cell (RBC) in the presence of albumin. Without albumin, there was no detectable C‐peptide binding per RBC. Rather than C‐peptide solely binding to a RBC receptor, we hypothesize that C‐peptide binds to RBCs through an albumin/C‐peptide complex receptor. Bovine serum albumin (BSA) binding per RBC was detectable through an attached gamma decay radiolabel (99mTc). A binding saturation experiment was conducted to examine the specific binding of BSA to RBCs with and without C‐peptide. The specific binding curves revealed that albumin saturates at 14,021 ± 1489 BSA molecules/RBC with a Kd of 1.07 (±0.19) × 10−7 M and a Bmax of 1.94 (±0.06) × 10−8 M, or 13,900 receptor molecules/RBC. Whereas, in the presence of C‐peptide and zinc, albumin saturates at 16,696 ± 1479 BSA molecules/RBC with a Kd of 1.91 (±0.09) × 10−7 M and a Bmax of 2.50 (±0.03) × 10−8 M, or 17,900 receptor molecules/RBC. At saturation, the additional 2,700 BSA molecules binding per RBC in the presence of C‐peptide and zinc indicates that an albumin receptor exists on RBCs as well as a separate albumin/C‐peptide complex receptor. Support or Funding Information NIH

A set of 3D-printed analytical devices were developed to investigate erythrocytes (ERYs) processed in conventional and modified storage solutions used in transfusion medicine. During storage prior to transfusion into a...

Serum albumin is a prominent plasma protein that becomes modified in hyperglycemic conditions. In a process known as glycation, these modifications can change the structure and function of proteins, which decrease ligand binding capabilities and alter the bioavailability of ligands. C-peptide is a molecule that binds to the red blood cell (RBC) and stimulates the release of adenosine triphosphate (ATP), which is known to participate in the regulation of blood flow. C-peptide binding to the RBC only occurs in the presence of albumin, and downstream signaling cascades only occur when the albumin and C-peptide complex contains Zn2+. Here, we measure the binding of glycated bovine serum albumin (gBSA) to the RBC in conditions with or without C-peptide and Zn2+. Key to these studies is the analytical sample preparation involving separation of BSA fractions with boronate affinity chromatography and characterization of the varying glycation levels with mass spectrometry. Results from this study show an increase in binding for higher % glycation of gBSA to the RBCs, but a decrease in ability to deliver C-peptide (0.75 ± 0.11 nM for 22% gBSA) compared to samples with less glycation (1.22 ± 0.16 nM for 13% gBSA). A similar trend was measured for Zn2+ delivery to the RBC as a function of glycation percentage. When 15% gBSA or 18% gBSA was combined with C-peptide/Zn2+, the derived ATP release from the RBCs significantly increased to 113% or 36%, respectively. However, 26% gBSA with C-peptide/Zn2+ had no significant increase in ATP release from RBCs. These results indicate that glycation of BSA interferes in C-peptide and Zn2+ binding to the RBC and subsequent RBC ATP release, which may have implications in C-peptide therapy for people with type 1 diabetes.