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Exerting forces on biomolecules inside living cells would allow us to probe their dynamic interactions in their native environment. Magnetic iron oxide nanoparticles represent a unique tool capable of pulling on biomolecules with the application of an external magnetic field gradient; however, their use has been restricted to biomolecules accessible from the extracellular medium. Targeting intracellular biomolecules represents an additional challenge due to potential nonspecific interactions with cytoplasmic or nuclear components. We present the synthesis of sulfobetaine-phosphonate block copolymer ligands, which provide magnetic nanoparticles that are stealthy and targetable in living cells. We demonstrate, for the first time, their efficient targeting in the nucleus and their use for magnetic micromanipulation of a specific genomic locus in living cells. We believe that these stable and sensitive magnetic nanoprobes represent a promising tool to manipulate specific biomolecules in living cells and probe the mechanical properties of living matter at the molecular scale.

In the last few years, zwitterionic polymers have been developed as antifouling surface coatings. However, their ability to completely suppress protein adsorption at the surface of nanoparticles in complex biological media remains undemonstrated. Here we investigate the formation of hard (irreversible) and soft (reversible) protein corona around model nanoparticles (NPs) coated with sulfobetaine (SB), phosphorylcholine (PC) and carboxybetaine (CB) polymer ligands in model albumin solutions and in whole serum. We show for the first time a complete absence of protein corona around SB-coated NPs, while PC- and CB-coated NPs undergo reversible adsorption or partial aggregation. These dramatic differences cannot be described by naïve hard/soft acid/base electrostatic interactions. Single NP tracking in the cytoplasm of live cells corroborate these in vitro observations. Finally, while modification of SB polymers with additional charged groups lead to consequent protein adsorption, addition of small neutral targeting moieties preserves antifouling and enable efficient intracellular targeting., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In the version of this Article originally published, Supplementary Videos 3-5 were incorrectly labelled; 3 should have been 5, 4 should have been 3 and 5 should have been 4. This has now been corrected.

The diffusivity of macromolecules in the cytoplasm of eukaryotic cells varies over orders of magnitude and dictates the kinetics of cellular processes. However, a general description that associates the Brownian or anomalous nature of intracellular diffusion to the architectural and biochemical properties of the cytoplasm has not been achieved. Here we measure the mobility of individual fluorescent nanoparticles in living mammalian cells to obtain a comprehensive analysis of cytoplasmic diffusion. We identify a correlation between tracer size, its biochemical nature and its mobility. Inert particles with size equal or below 50 nm behave as Brownian particles diffusing in a medium of low viscosity with negligible effects of molecular crowding. Increasing the strength of non-specific interactions of the nanoparticles within the cytoplasm gradually reduces their mobility and leads to subdiffusive behaviour. These experimental observations and the transition from Brownian to subdiffusive motion can be captured in a minimal phenomenological model.

We reviewed the records of 15 Human Immunodeficiency Virus (HIV) infected patients with pulmonary cryptococcosis (PC). PC was the first AIDS-defining manifestation in nine patients. HIV infection was identified simultaneously with the onset of PC in 4 patients. The CD4+ lymphocyte count was low in all cases (median, 24/m3). Chest radiography showed interstitial infiltrates in 13 instances, associated with pleural effusion in 5 cases and hilar adenopathy in 2 cases. In one case, chest-X-ray showed isolated pleural effusion and was normal in one patient. For 11 of 12 patients, bronchoalveolar lavage fluid culture was positive for Cryptococcus neoformans. Seven of 15 patients had evidence of extrapulmonary cryptococcal disease with positive cerebrospinal fluid culture. Serum cryptococcal antigen was detected in all 15 patients. Concomitant lung infection with Pneumocystis carinii was diagnosed in 4 patients. First-line regimen was fluconazole in 10 patients and amphotericin B in 4 patients. Fluconazole has been prescribed in 7 patients as a permanent suppressive therapy and should be continued indefinitely.

Herein is a report of an adult case of primary HIV infection with cytomegalovirus coinfection causing cough, fever, and lymphocytic alveolitis. Primary HIV infection has not been previously reported as a cause of lymphocytic alveolitis.

We report a case of a young burkinabian, who presented with the disseminated african form of histoplasmosis, Histoplasma duboisii. There was pulmonary mediastinal disease with superficial lymphadenopathy and also hepatic involvement. The diagnosis was achieved by a histological examination of the peripheral glands and micrological examination of the expectorate. A clinical cure (despite the radiological persistence of enlarged but stable left hilar glands) with the follow up 10 months was achieved after 15 months of treatment with ketoconazole in a dose which was increased to 10 mg/kg/day.