Colloidal quantum dots (CQDs) are coming up as appealing platform, as exciting class of fluorescent probes for optical imaging, because of their tunable and unique optical properties, high stability and ability to target affected tissue, based on their surface functionalization compared to small molecules of organic dyes. More empathetically, it has been observed that the current dyes lack the signal penetration needed for optimal performance, the tissue specification, and stability in metabolic systems and photo bleaching resistivity properties. Thus, semiconducting QDs represent an exciting class of luminescent materials with favourable fluorescent properties like narrow emission band; efficient stokes shift and long fluorescent lifetime. Most specifically, tunable fluorescence ranging from UV-blue to the mid infrared emission to maintain high resolution for deeper imaging can be achieved by altering the size, size distribution and crystal structure of the QDs. These potential properties make QDs suitable as direct substitutes for the existing dyes. From the last 5-6 years, the application of fluorescent QDs, as probes for biological domain are emerging as smart bio-medical imaging, bio-tagging and drug delivery agents leading to a highly promising technique as fluorescent based techniques are very sensitive. However, decision of making QDs as the future heir of the present day drug associates/dyes, is still perplexed as their toxicity is a matter of great concern. Toxicity has become an integral part of QDs mainly due to a) non-surface passivation, b) oxidative degradation, c) poor biocompatibility and d) choosing of nonbiocompatible capping agents. Therefore efforts are going on to neutralize these threats during the synthesis part only, by surface functionalizing the QDs with better biocompatibility and cytofriendlyness. Since, these QDs are self-sufficient to heal any bacterial growth when bacteria are in touch with them, keeping in view of having tremendous potential application as tagging, imaging and antibacterial agents in biological systems, the present work reports the preparation, characterization and biocompatibility of semiconducting QDs with surface modifications to establish them as efficient fluorescent probes in health and medical sector.
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