The development of efficient, reliable, and easy-to-use biosensors allowing early cancer diagnosis is of paramount importance for patients. Herein, we report a biosensor based on silver nanoparticles functionalized by peptide aptamers for the detection of a cancer biomarker, i. e. the Mdm2 protein. Silver nanoparticles (AgNPs) were produced and stabilized with a thin PEGylated-calix[4]arene layer that allows (i) the steric stabilization of the AgNPs and (ii) the covalent conjugation of the peptide aptamers via the formation of an amide bond. These peptide-conjugated AgNPs were then used to detect Mdm2 via a dual trapping strategy that was previously reported with gold nanoparticles (AuNPs). Our results showed that replacing AuNPs by AgNPs improves the detection limit by nearly one order of magnitude, down to 5 nM, while the high selectivity of the system and the stability of the particles provided by the calixarene coating allow the detection of Mdm2 in human serum.

Restenosis remains the major limitation of coronary angioplasty. The objective of this study was to develop microspheres able to be delivered at the angioplasty site for long-term drug release and to test their effects in a model of balloon angioplasty. Polylactic-co-glycolide acid microspheres (5-10 microm in diameter) were prepared by using an oil-in-water emulsion-solvent evaporation method. In vitro experiments with hydrocortisone-loaded microspheres revealed a hydrocortisone release for 4 weeks. We studied the in vivo effect of injection of microspheres into the arterial wall of New Zealand White rabbits by using a perforated balloon. Deep penetration of microspheres in the arterial wall was documented immediately after angioplasty. Intimal hyperplasia was assessed in iliac arteries 4 weeks after angioplasty. The morphometric analysis was performed in four groups of animals; the first group was subjected only to conventional angioplasty (control, n = 10), whereas the other three groups after conventional angioplasty were received perforated balloon angioplasty with saline (n = 10), microspheres (n = 10), or hydrocortisone-loaded microspheres (n = 7). Intramural injection of saline did not induce greater intimal hyperplasia compared with control (0.17 +/- 0.03 vs. 0.18 +/- 0.03 mm2, respectively). Microspheres injection was associated with a trend toward a greater degree of intimal hyperplasia that did not reach statistical significance. Hydrocortisone-loaded microspheres were associated with a significant reduction in intimal hyperplasia compared with unloaded microspheres (0.16 +/- 0.02 vs. 0.26 +/- 0.03 mm2, respectively). The polylactic-co-glycolide acid microspheres are well tolerated, easily injected into the arterial wall, and the increase of intimal hyperplasia is easily inhibited by release of hydrocortisone for 4 weeks after initial injury.

Silver nanoparticles (AgNPs) were deliberately functionalized via aryl diazonium chemistry with a monolayer of calix[4]arenes. The resulting nanohybrids show high efficiency, high selectivity toward ORR in alkaline media along with...

Dipstick assays using silver nanoparticles (AgNPs) stabilized by a thin calix[4]arene-based coating were developed and used for the detection of Anti-SARS-CoV-2 IgG in clinical samples. The calixarene-based coating enabled the covalent bioconjugation of the SARS-CoV-2 Spike Protein via the classical EDC/sulfo-NHS procedure. It further conferred remarkable stability to the resulting bioconjugated AgNPs, as no degradation was observed over several months. In comparison with lateral-flow immunoassays (LFIAs) based on classical gold nanoparticles, our AgNP-based system constitutes a clear step forward, as the limit of detection for Anti-SARS-CoV-2 IgG was reduced by 1 order of magnitude and similar signals were observed with 10 times fewer particles. In real clinical samples, the AgNP-based dipstick assays showed impressive results: 100% specificity was observed for negative samples, while a sensitivity of 73% was determined for positive samples. These values match the typical sensitivities obtained for reported LFIAs based on gold nanoparticles. These results (i) represent one of the first examples of the use of AgNP-based dipstick assays in the case of real clinical samples, (ii) demonstrate that ultrastable calixarene-coated AgNPs could advantageously replace AuNPs in LFIAs, and thus (iii) open new perspectives in the field of rapid diagnostic tests.

Invited for this month's cover are the collaborating groups of Prof. Gilles Bruylants and Prof. Ivan Jabin, Université libre de Bruxelles, Belgium. The cover picture shows the principle of a colorimetric sensor, based on peptide‐conjugated silver nanoparticles, for the detection of the cancer biomarker Mdm2. The particles were functionalized via a recently developed strategy based on the use of calixarene diazonium salts. The calixarene‐based coating provides an unprecedented stability to the silver nanoparticles, enabling their use as colorimetric reporters for in vitro diagnostics. The cover was designed by I. Jabin. More information can be found in the Research Article by I. Jabin, G. Bruylants, and co‐workers.