Nanodiamond emulsions for enhanced quantum sensing and click-chemistry conjugation

Nanodiamonds containing nitrogen-vacancy (NV) centers can serve as colloidal quantum sensors of local fields in biological and chemical environments. However, nanodiamond surfaces are challenging to modify without degrading their colloidal stability or the NV center's optical and spin properties. Here, we report a simple and general method to coat nanodiamonds with a thin emulsion layer that preserves their quantum features, enhances their colloidal stability, and provides functional groups for subsequent crosslinking and click-chemistry conjugation reactions. To demonstrate this technique, we decorate the nanodiamonds with combinations of carboxyl- and azide-terminated amphiphiles that enable conjugation using two different strategies. We study the effect of the emulsion layer on the NV center's spin lifetime, and we quantify the nanodiamonds' chemical sensitivity to paramagnetic ions using $T_1$ relaxometry. This general approach to nanodiamond surface functionalization will enable advances in quantum nanomedicine and biological sensing.Comment: 52 pages, 42 figures (main text plus supplementary information

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Early short-term treatment with neutralizing human monoclonal antibodies halts SHIV infection in infant macaques

Prevention of mother-to-child transmission (MTCT) of HIV remains a major objective where antenatal care is not readily accessible. We tested HIV-1–specific human neutralizing monoclonal antibodies (NmAbs) as a post-exposure therapy in an infant macaque model for intrapartum MTCT. One-month-old rhesus macaques were inoculated orally with the simian-human immunodeficiency virus SHIVSF162P3. On days 1, 4, 7 and 10 after virus exposure, we injected animals subcutaneously with NmAbs and quantified systemic distribution of NmAbs in multiple tissues within 24 h after antibody administration. Replicating virus was found in multiple tissues by day 1 in animals that were not treated. All NmAb-treated macaques were free of virus in blood and tissues at 6 months after exposure. We detected no anti-SHIV T cell responses in blood or tissues at necropsy, and no virus emerged after CD8+ T cell depletion. These results suggest that early passive immunotherapy can eliminate early viral foci and thereby prevent the establishment of viral reservoirs.Fil: Hessell, Ann J.. Oregon Health and Science University; Estados UnidosFil: Jaworski, Juan Pablo. Oregon Health and Science University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Epson, Erin. Oregon Health and Science University; Estados UnidosFil: Matsuda, Kenta. National Institutes of Health; Estados UnidosFil: Pandey, Shilpi. Oregon Health and Science University; Estados UnidosFil: Kahl, Christoph. Oregon Health and Science University; Estados UnidosFil: Reed, Jason. Oregon Health and Science University; Estados UnidosFil: Sutton, William F.. Oregon Health and Science University; Estados UnidosFil: Hammond, Katherine B.. Oregon Health and Science University; Estados UnidosFil: Cheever, Tracy A.. Oregon Health and Science University; Estados UnidosFil: Barnette, Philip T.. Oregon Health and Science University; Estados UnidosFil: Legasse, Alfred W.. Oregon Health and Science University; Estados UnidosFil: Planer, Shannon. Oregon Health and Science University; Estados UnidosFil: Stanton, Jeffrey J.. Oregon Health and Science University; Estados UnidosFil: Pegu, Amarendra. National Institutes of Health; Estados UnidosFil: Chen, Xuejun. National Institutes of Health; Estados UnidosFil: Wang, Keyun. National Institutes of Health; Estados UnidosFil: Siess, Don. Oregon Health and Science University; Estados UnidosFil: Burke, David. Oregon Health and Science University; Estados UnidosFil: Park, Byung S.. Oregon Health and Science University; Estados UnidosFil: Axthelm, Michael K. Oregon Health and Science University; Estados UnidosFil: Lewis, Anne. Oregon Health and Science University; Estados UnidosFil: Hirsch, Vanessa M.. National Institutes of Health; Estados UnidosFil: Graham, Barney S.. National Institutes of Health; Estados UnidosFil: Mascola, John R.. National Institutes of Health; Estados UnidosFil: Sacha, Jonah B.. Oregon Health and Science University; Estados UnidosFil: Haigwood, Nancy L.. Oregon Health and Science University; Estados Unido