The development of molecular probes for the detection and imaging of biological thiols is a major step forward diagnosing various types of diseases. Previously reported thiol imaging strategies were ...mainly based on a single mode of imaging with a limited application
. In this work, we introduced an unsymmetrical near-infrared (NIR) squaraine dye (USq) as an exogenous contrast agent for photoacoustic and fluorescence bimodal imaging of thiol variations in live animals. USq exhibits a narrow absorption band at 680 nm that generates a photoacoustic signal and a strong NIR emission at 700 nm (
= 0.27), which is applicable for deep tissue optical imaging. Both photoacoustic and fluorescence signals could selectively disappear in the presence of different thiols. Through
and
imaging studies, unique imaging capability of USq was demonstrated, and the effect of food uptake on the increased level of aminothiols in blood was confirmed.
Passive endocytosis in model protocells Zhang, Stephanie J; Lowe, Lauren A; Anees, Palapuravan ...
Proceedings of the National Academy of Sciences - PNAS,
06/2023, Letnik:
120, Številka:
24
Journal Article
Recenzirano
Odprti dostop
Semipermeable membranes are a key feature of all living organisms. While specialized membrane transporters in cells can import otherwise impermeable nutrients, the earliest cells would have lacked a ...mechanism to import nutrients rapidly under nutrient-rich circumstances. Using both experiments and simulations, we find that a process akin to passive endocytosis can be recreated in model primitive cells. Molecules that are too impermeable to be absorbed can be taken up in a matter of seconds in an endocytic vesicle. The internalized cargo can then be slowly released over hours, into the main lumen or putative cytoplasm. This work demonstrates a way by which primitive life could have broken the symmetry of passive permeation prior to the evolution of protein transporters.
Lysosomal calcium (Ca
) release is critical to cell signaling and is mediated by well-known lysosomal Ca
channels. Yet, how lysosomes refill their Ca
remains hitherto undescribed. Here, from an RNA ...interference screen in
, we identify an evolutionarily conserved gene,
, that facilitates lysosomal Ca
entry in
and mammalian cells. We found that its human homolog TMEM165, previously designated as a Ca
/H
exchanger, imports Ca
pH dependently into lysosomes. Using two-ion mapping and electrophysiology, we show that TMEM165, hereafter referred to as human LCI, acts as a proton-activated, lysosomal Ca
importer. Defects in lysosomal Ca
channels cause several neurodegenerative diseases, and knowledge of lysosomal Ca
importers may provide previously unidentified avenues to explore the physiology of Ca
channels.
This study demonstrates that pH-responsive polymers have a very high buffering capacity in their immediate vicinity, a phenomenon termed “nanobuffering”. This can be exploited to dissociate local ...nanoscale pH from bulk solution pH. Herein, a series of pH-responsive polymers were conjugated to Protein-A to rationally manipulate the latter’s binding affinity toward antibodies via nanobuffering (i.e., this interaction is pH dependent), independently of bulk solution pH. Moreover, the nanobuffering effect could be terminated using low concentrations of strong ion-pairing salts, to achieve quantitative release of the antibodies from the bioconjugate. These complementary discoveries are showcased in the context of the development of a homogeneous affinity precipitation agent (i.e., a scavenger) for the purification of polyclonal immunoglobulin G and two monoclonal antibodies from cell culture supernatant. Indeed, while bulk solution pH was used to induce precipitation of the scavenger, maintaining local nanoscale pH via nanobuffering maximized binding interaction with the antibodies. A 2:1 binding stoichiometry was observed, which was similar to that observed for native protein. The scavenger could be recycled multiple times, and the purification protocol circumvented lengthy/tedious physical purification processes typically associated with mAb manufacturing. Overall, this study provides perspectives on the local nanoscale pH near pH-responsive polymers and establishes lines of thought for predictably manipulating or even terminating nanobuffering, to control the activity of proteins.
A two-component hybrid system consisting of organic dye nanoparticles (ash) and a protein (blue) at different ratios allows for the design of narrow range tunable nanoprobes for sensing and imaging ...of pH variations in live cells through ratiometric signalling.
Accurate monitoring of pH variations inside cells is important for the early diagnosis of diseases such as cancer. Even though a variety of different pH sensors are available, construction of a custom-made sensor array for measuring minute variations in a narrow biological pH window, using easily available constituents, is a challenge. Here we report two-component hybrid sensors derived from a protein and organic dye nanoparticles whose sensitivity range can be tuned by choosing different ratios of the components, to monitor the minute pH variations in a given system. The dye interacts noncovalently with the protein at lower pH and covalently at higher pH, triggering two distinguishable fluorescent signals at 700 and 480 nm, respectively. The pH sensitivity region of the probe can be tuned for every unit of the pH window resulting in custom-made pH sensors. These narrow range tunable pH sensors have been used to monitor pH variations in HeLa cells using the fluorescence imaging technique.
Carbon nanodots (CNDs) have attracted substantial scientific curiosity because of their intriguing stimuli-responsive optical properties. However, one obstacle to the more widespread use of CNDs as ...transducers for
e.g.
, biodetection systems is incomplete knowledge regarding the underlying chemical changes responsible for this responsiveness, and how these chemical features can be engineered
via
the precursors chosen for CND synthesis. This study demonstrates that the precursor's functional groups play a key role in directing N/S/Se heteroatom dopants either towards the surface of the CNDs, towards the aromatic core, or towards small organic fluorophores in the core. Divergent optical properties, which were consistent amongst groups of CNDs prepared with similar precursors, were obtained including either a decrease or increase of fluorescence intensity in the presence of hydrogen peroxide. Moreover, CNDs were identified with orthogonal responsiveness to radical (hydroxyl radicals, &z.rad;OH; down to 2.5 μM)
vs.
non-radical oxidants (H
2
O
2
; down to 50 μM), which suggests that control of the chemistry of CNDs
via
the choice of precursor could yield probes that are specific to certain sub-species of reactive oxygen species or entirely different molecules altogether, based on the way they chemically-modify the surface (respond faster) and core functional groups (respond slower) associated with chromophores/fluorophores of which the CNDs are composed.
This study explores chemical changes that occur to five carbon nanodots upon exposure to oxidants, and relates these to changes of their optical properties.
The development of molecular probes for the detection and imaging of biological thiols is a major step forward diagnosing various types of diseases. Previously reported thiol imaging strategies were ...mainly based on a single mode of imaging with a limited application
in vivo
. In this work, we introduced an unsymmetrical near-infrared (NIR) squaraine dye (USq) as an exogenous contrast agent for photoacoustic and fluorescence bimodal imaging of thiol variations in live animals. USq exhibits a narrow absorption band at 680 nm that generates a photoacoustic signal and a strong NIR emission at 700 nm (
Φ
F
= 0.27), which is applicable for deep tissue optical imaging. Both photoacoustic and fluorescence signals could selectively disappear in the presence of different thiols. Through
in vitro
and
in vivo
imaging studies, unique imaging capability of USq was demonstrated, and the effect of food uptake on the increased level of aminothiols in blood was confirmed.
Real time monitoring of blood aminothiol level by a near-IR dye assisted fluorescence-photoacoustic bimodal imaging is reported.
Real time monitoring of blood aminothiol level by a near-IR dye assisted fluorescence–photoacoustic bimodal imaging is reported.
The development of molecular probes for the detection and imaging of ...biological thiols is a major step forward diagnosing various types of diseases. Previously reported thiol imaging strategies were mainly based on a single mode of imaging with a limited application
in vivo
. In this work, we introduced an unsymmetrical near-infrared (NIR) squaraine dye (USq) as an exogenous contrast agent for photoacoustic and fluorescence bimodal imaging of thiol variations in live animals. USq exhibits a narrow absorption band at 680 nm that generates a photoacoustic signal and a strong NIR emission at 700 nm (
Φ
F
= 0.27), which is applicable for deep tissue optical imaging. Both photoacoustic and fluorescence signals could selectively disappear in the presence of different thiols. Through
in vitro
and
in vivo
imaging studies, unique imaging capability of USq was demonstrated, and the effect of food uptake on the increased level of aminothiols in blood was confirmed.
Periodic mesoporous organosilica (PMO) has been widely used for the fabrication of a variety of catalytically active materials. We report the preparation of novel photo-responsive PMO with ...azobenzene-gated pores. Upon activation, the azobenzene gate undergoes trans-cis isomerization, which allows an unsymmetrical near-infrared squaraine dye (Sq) to enter into the pores. The gate closure by cis-trans isomerization of the azobenzene unit leads to the safe loading of the monomeric dye inside the pores. The dye-loaded and azobenzene-gated PMO (Sq-azo@PMO) exhibits excellent generation of reactive oxygen species upon excitation at 664 nm, which can be effectively used for the oxidation of phenol into benzoquinone in aqueous solution. Furthermore, Sq-azo@PMO as the catalyst was placed inside a custom-built, continuous-flow device to carry out the photo-oxidation of phenol to benzoquinone in the presence of 664-nm light. By using the device, about 23% production of benzoquinone with 100% selectivity was achieved. The current research presents a prototype of transforming heterogeneous catalysts toward practical use.
Carbon nanodots (CNDs) have attracted substantial scientific curiosity because of their intriguing stimuli-responsive optical properties. However, one obstacle to the more widespread use of CNDs as ...transducers for e.g. , biodetection systems is incomplete knowledge regarding the underlying chemical changes responsible for this responsiveness, and how these chemical features can be engineered via the precursors chosen for CND synthesis. This study demonstrates that the precursor's functional groups play a key role in directing N/S/Se heteroatom dopants either towards the surface of the CNDs, towards the aromatic core, or towards small organic fluorophores in the core. Divergent optical properties, which were consistent amongst groups of CNDs prepared with similar precursors, were obtained including either a decrease or increase of fluorescence intensity in the presence of hydrogen peroxide. Moreover, CNDs were identified with orthogonal responsiveness to radical (hydroxyl radicals, ˙OH; down to 2.5 μM) vs. non-radical oxidants (H 2 O 2 ; down to 50 μM), which suggests that control of the chemistry of CNDs via the choice of precursor could yield probes that are specific to certain sub-species of reactive oxygen species or entirely different molecules altogether, based on the way they chemically-modify the surface (respond faster) and core functional groups (respond slower) associated with chromophores/fluorophores of which the CNDs are composed.
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