Bi-ligand surfaces with oriented and patterned protein for real-time tracking of cell migration.

A bioactive platform for the quantitative observation of cell migration is presented by (1) presenting migration factors in a well-defined manner on 2-D substrates, and (2) enabling continuous cell tracking. Well-defined substrate presentation is achieved by correctly orienting immobilized proteins (chemokines and cell adhesion molecules), such that the active site is accessible to cell surface receptors. A thiol-terminated self-assembled monolayer on a silica slide was used as a base substrate for subsequent chemistry. The thiol-terminated surface was converted to an immobilized metal ion surface using a maleimido-nitrilotriacetic acid (NTA) cross-linker that bound Histidine-tagged recombinant proteins on the surface with uniform distribution and specific orientation. This platform was used to study the influence of surface-immobilized chemokine SDF-1α and cell adhesion molecule ICAM-1 on murine splenic B lymphocyte migration. While soluble SDF-1α induced trans-migration in a Boyden Chamber type chemotaxis assay, immobilized SDF-1α alone did not elicit significant surface-migration on our test-platform surface. Surface-immobilized cell adhesion protein, ICAM-1, in conjunction with activation enabled migration of this cell type on our surface. Controlled exposure to UV light was used to produce stable linear gradients of His-tagged recombinant SDF-1α co-immobilized with ICAM-1 following our surface chemistry approach. XPS and antibody staining showed defined gradients of outwardly oriented SDF-1α active sites. This test platform can be especially valuable for investigators interested in studying the influence of surface-immobilized factors on cell behavior and may also be used as a cell migration enabling platform for testing the effects of various diffusible agents.

Diatoms: a biotemplating approach to fabricating drug delivery reservoirs.

Biotemplating is a rapidly expanding subfield that utilizes nature-inspired systems and structures to create novel functional materials, and it is through these methods that the limitations of current engineering practices may be advanced. The diatom is an exceptional template for drug delivery applications, owing largely to its highly-ordered pores, large surface area, species-specific architecture, and flexibility for surface modifications. Diatoms have been studied in a wide range of biomedical applications and their potential as the next frontier of drug delivery has yet to be fully exploited. In this editorial, the authors aim to review the use of diatoms in the delivery of poorly water-soluble drugs as reported in the literature, discuss the progress and advancements that have been made thus far, identify the shortcomings and limitations in the field, and, lastly, present their expert opinion and convey the future outlook on biotemplating approaches for drug delivery.