Small Gold Quantum Probes for Drug‐Free Cancer Theranostics

Gold quantum dots (QDs) have emerged as a distinct approach for cancer theranostics by using labeled and functionalized chemotherapeutic‐drug to realize its detection and chemotherapeutic functions. However, the toxicity induced by chemical‐based synthesis, their nonspecific accumulation in healthy tissues and organs hamper its translation to clinical applications. QDs are functionalized/labeled to reduce their toxicity and helps the QDs' cellular‐uptake. In addition, labeling increases the overall hydrodynamic size of QDs, which limits the dispersion, impedes efficient renal clearance and causes the accumulation of QDs in organs. Therefore, the unique properties that arise from quantum‐size (less than 5nm) are lost. Reports on the effect of real quantum‐size on cell‐interaction are, to date, limited. In this work, the concept of a small‐sized self‐functionalized pristine bright quantum gold probe (BQGP) for cancer‐theranostics. To the best of authors' knowledge, it is the first time cell‐interaction of BQGPs has been investigated and the results suggest that it can be used for label‐free/drug‐free cancer quantum‐theranostics. The pristine BQGPs demonstrate cancer‐selective cell‐uptake, enabling dosage‐dependent fluorescent detection/differentiation of cancerous‐cells and cancer‐selective cytotoxicity. The fabricated BQGPs demonstrate fluorophore‐free illuminance at a broad‐range of excitation wavelengths and drug‐free cancer‐specific treatment. Moreover, the drug‐free BQGPs may find advantages in fighting drug‐resistant cancers.