Herein,
we report a new strategy based on jacalin functionalization
to diminish the impact of biological fluids in the antibacterial applications
of nanoparticles (NPs). Precoating pectin-capped copper sulfide NPs
(pCuS) with bovine serum albumin produced a protein corona, which
affects the antibacterial activity of pCuS. It was found that the
minimum inhibitory concentration (MIC) increases fourfold because
of the formation of the protein corona. Interestingly, the pCuS functionalized
with jacalin enhance the targeting capabilities through bacterial
cell surface glycan recognition with no interference from the protein
corona. The MIC of pCuS decreases 16-fold on functionalization with
jacalin. Mechanistic studies indicated that the pCuS functionalized
with jacalin impede the protein corona interference and induce bacterial
cell death by impairing the GSH/reactive oxygen species balance and
disrupting the bacteria cell membrane. As a proof of concept, we used
a bacteria-infected zebrafish animal model to demonstrate the interference
of biological fluids in the antibacterial activity of NPs. Infected
zebrafish treated with 1× MIC of pCuS failed to recover from
the infection, but 4× MIC rescues the fish. The requirement of
a high dose of NPs to treat the infection confirms the interference
of biological fluids in nanotherapeutic applications. At the same
time, the jacalin–pCuS complex rescues the infected fish at
16-fold lesser MIC. The results obtained from this study suggest that
jacalin-mediated NP targeting may have broad implications in the development
of future nanomedicine.
Mercury exists in organic, inorganic, and elemental forms; all of them are highly toxic. A sensor which could detect all forms of mercury below the permissible level in environmental and biological samples would be advantageous. A facile method to synthesize N-acetyl cysteine capped cadmium selenide quantum dots (CdSe QDs) with an emission at 554 nm was reported. CdSe QDs showed high sensitivity and selectivity toward Hg in aqueous media as well as biological fluids like simulated cerebrospinal fluid, saliva, and urine, and also in natural fluids like juices of tomato, sugarcane, and lime. The sensing mechanism is attributed to the interactions between Hg and CdSe QDs inducing fluorescence quenching. The limit of detection is 1.62, 0.75, and 1.27 ppb for organic, inorganic and elemental mercury, respectively, which is below WHO guidelines. The suitability of the sensor for estimating Hg in biological fluids was demonstrated by recovery experiments. Besides sensing, a two color cell imaging method was developed employing CdSe QDs and acridine orange. Using this method, the uptake of Hg in living cells was demonstrated.
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