Interstitial Fluid Biomarkers’ Minimally Invasive Monitoring Using Microneedle Sensor Arrays

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Skin interstitial fluid (ISF) is a biofluid with information-rich biomarkers for disease diagnosis and prognosis. Microneedle (MN) integration of sampling and instant biomarker readout hold great potential in health status monitoring and point-of-care testing (POCT). The present work describes an attractive MN sensor array for minimally invasive monitoring of ISF microRNA (miRNA) and Cu2+.

The MN array is made of methacrylated gelatin (GelMA) and methacrylated hyaluronic acid (MeHA), and a further divisionally encapsulated miRNA and Cu2+ detection system, and is cross-linked through blue-light irradiation.

The MN patch displays good mechanical properties that enable withstanding more than 0.4 N per needle, and exhibits a high swelling ratio of 700% that facilitates timely extraction of sufficient ISF for biomarker analysis. For proof-of-concept, it realizes detection of miRNAs and Cu2+ efficiently and quantitatively in an agarose skin and fresh porcine cadaver skin model. Given the good sampling and in situ monitoring ability, the MN array holds great promise for skin ISF-based applications.

Colorimetric Detection of Organophosphate Pesticides Based on Acetylcholinesterase and Cysteamine Capped Gold Nanoparticles as Nanozyme

Organophosphates (OPs) are neurotoxic agents also used as pesticides that can permanently block the active site of the acetylcholinesterase (AChE). A robust and sensitive detection system of OPs utilising the enzyme mimic potential of the cysteamine capped gold nanoparticles (C-AuNPs) was developed. The detection assay was performed by stepwise addition of AChE, parathion ethyl (PE)-a candidate OP, acetylcholine chloride (ACh), C-AuNPs, and 3, 3′, 5, 5′-tetramethylbenzidine (TMB) in the buffer solution.

The whole sensing protocol completes in 30-40 min, including both incubations. The Transmission Electron Microscopy (TEM) results indicated that the NPs are spherical and have an average size of 13.24 nm.

The monomers of C-AuNPs exhibited intense catalytic activity (nanozyme) for the oxidization of TMB, revealed by the production of instant blue colour and confirmed by a sharp peak at 652 nm. The proposed biosensor’s detection limit and linear ranges were 5.8 ng·mL-1 and 11.6-92.8 ng·mL-1, respectively, for PE. The results strongly advocate that the suggested facile colorimetric biosensor may provide an excellent platform for on-site monitoring of OPs.

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Coomassie Blue G 250
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A bovine nucleus pulposus explant culture model

Low back pain is a global health problem that is frequently caused by intervertebral disc degeneration (IVDD). Sulphated glycosaminoglycans (sGAGs) give the healthy nucleus pulposus (NP) a high fixed charge density (FCD), which creates an osmotic pressure that enables the disc to withstand high compressive forces. However, during IVDD sGAG reduction in the NP compromises biomechanical function. The aim of this study was to develop an ex vivo NP explant model with reduced sGAG content and subsequently investigate biomechanical restoration via injection of proteoglycan containing notochordal cell-derived matrix (NCM).
Bovine coccygeal NP explants were cultured in a bioreactor chamber and sGAG loss was induced by chondroitinase ABC (chABC) and cultured for up to 14 days. Afterwards, diurnal loading was studied, and explant restoration was investigated via injection of NCM. Explants were analyzed via histology, biochemistry and biomechanical testing via stress relaxation tests and height measurements. ChABC injection induced dose-dependent sGAG reduction on day 3, however, no dosing effects were detected after 7 and 14 days. Diurnal loading reduced sGAG loss after injection of chABC.
NCM did not show an instant biomechanical (equilibrium pressure) or biochemical (FCD) restoration, as the injected fixed charges leached into the medium, however, NCM stimulated proliferation and increased Alcian blue staining intensity and matrix organization. NCM has biological repair potential and biomaterial/NCM combinations, which could better entrap NCM within the NP tissue, should be investigated in future studies. Concluding, chABC induced progressive, time-, dose- and loading-dependent sGAG reduction that led to a loss of biomechanical function.

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