In the last decade, the advent of 3D printing for tissue engineering and regenerative medicine has engendered great interest for those involved in skin repair and regeneration. 3D bioprinting allows spatial distribution of skin cells into predefined custom‐made structures to produce living skin mimics on the bench for grafting or drug testing. The key aspect of 3D bioprinting lies in the formulation of printable bioinks serving as matrix mimics to house skin cells, alongside an appropriate combination of cells. In this review, bioink formulations, cell combinations, as well as manufacturing methods exploited to develop 3D bioprinted constructs for skin regeneration are summarized. Issues to do with the selection of suitable materials and cells to ensure the functionality of the resulting skin constructs and fabrication of skin appendages are also addressed.

BackgroundRapid detection and discrimination of bacteria for biomedical and food safety applications remain a considerable challenge. We report a label-free near infrared surface-enhanced Raman scattering (NIR-SERS) method for the discrimination of pathogenic bacteria from drinking water. The approach relies on the in situ synthesis of silver nanoparticles (Ag NPs) within the bacterial cell suspensions.ResultsPre-treatment of cells with Triton X-100 significantly improved the sensitivity of the assay. Using this method, we were able to discriminate several common pathogenic bacteria such as Escherichia coli, Pseudomonas aeruginosa, Methicillin-resistant Staphylococcus aureus (MRSA) and Listeria spp. A comparison of the SERS spectra allowed for the discrimination of two Listeria species, namely L. monocytogenes and L. innocua. We further report the application of the method to discriminate two MRSA strains from clinical isolates. The complete assay was completed in a span of 5 min.ConclusionsThe proposed analytical method proves to be a rapid tool for selective and label-free identification of pathogenic bacterium. Pre-treatment of bacterial cells with Triton X-100 resulted in new features on the SERS spectra, allowing for a successful discrimination of common disease related bacteria including E. coli, P. aeruginosa, Listeria and MRSA. We also demonstrate that the spectral features obtained using in situ synthesis of nanoparticles could be could be used to differentiate two species of listeria. By using L.innocua as a model sample, we found the limit of detection of our assay to be 103 CFU/mL. The method can selectively discriminate different bacterial species, and has a potential to be used in the development of point-of-care diagnostics with biomedical and food safety applications.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-015-0106-4) contains supplementary material, which is available to authorized users.

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