Fluorescence imaging assisted photodynamic therapy (PDT) is a viable two-in-one clinical tool for cancer treatment and follow-up. While the surface plasmon effect of gold nanorods and nanoparticles has been effective for cancer therapy, their emission properties when compared to gold nanoclusters are weak for fluorescence imaging guided PDT. In order to address the above issues, we have synthesized a near-infrared-emitting gold quantum cluster capped with lipoic acid (L-AuC with (Au)18(L)14) based nanoplatform with excellent tumor reduction property by incorporating a tumor-targeting agent (folic acid) and a photosensitizer (protoporphyrin IX), for selective PDT. The synthesized quantum cluster based photosensitizer PFL-AuC showed 80% triplet quantum yield when compared to that of the photosensitizer alone (63%). PFL-AuC having 60 μg (0.136 mM) of protoporphyrin IX was sufficient to kill 50% of the tumor cell population. Effective destruction of tumor cells was evident from the histopathology and fluorescence imaging, which confirm the in vivo PDT efficacy of PFL-AuC.

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Quantum dots and noble metal quantum cluster (QC) based fl uorescent probes are of interest for the detection of specifi c analytes of biological as well as nonbiological origin. [ 1 ] They exhibit size tunable fl uorescence emission ranging from UV/Vis to NIR region. [ 2 ] When compared to semiconductor quantum dots, gold clusters (AuCs) are advantageous due to the less toxicity of the latter. Applications of gold clusters include targeted cancer imaging, biological labeling, detection of proteases, glutaraldehyde, Cu 2 + , Hg 2 + , CN − , As 3 + as well as explosives such as TNT. [ 1e-m ] Majority of the QC based sensors are based on analyte induced fl uorescence variation in the UV/Vis region. While such sensors are useful for the analysis of a variety of samples, they are not appropriate for biological samples such as blood and other colloidal samples. For example, for the direct analysis of blood samples, due to the autofl uorescence and strong color, fl uorescent probes that emit in the NIR region are preferred over those emitting in the visible region. Herein, we report a gold cluster based nanosensor (AuC@Urease) for the selective and direct detection of urea in blood samples and hence has relevance in clinical diagnosis and health care. The main advantage of the proposed sensing mechanism is that it works directly on the blood whereas currently adopted clinical methods require serum separation for the detection of urea, as many of them work on colorimetric assay which is often hindered by the color of blood. Moreover, this highly sensitive and direct sensing method has the advantage of providing quick results as there is no need of serum separation.Urea is a byproduct of protein metabolism that is formed in the liver, carried by the blood and excreted through the kidney in urine. Therefore, urea is an important marker for evaluating uremic toxin levels and kidney and hepatocellular functions. [ 3 ] Urea detection is also important in the estimation of non-protein nitrogen in food products such as milk since it is known that urea adulteration is utilized as an indicator of protein feeding effi ciency. [ 4 ] Nanosensors based on metal nanoparticles (NPs) have got wide attention during the past couple of decades because of their enhanced selectivity and sensitivity towards specifi c analytes. [ 5 , 6 ] There are several reports on nanosensors for the detection of urea, most of which are based on electrochemical or amperometric sensing. [ 7 ] In a recent report, urease functionalized gold nanoparticles were used as a conductometric biosensor for the detection of urea. [ 7k ] The design of the nanosensor started with the preparation of AuC by the process of etching mercapto succinic acid conjugated gold nanoparticles (AuNPs, 5-7 nm, Figure S1) in the presence of glutathione (GSH) at 0 ° C followed by 20 min incubation and subsequent heating at 70 ° C, maintaining the pH at 1.5. The color of the solution changed from dark brown to light yellow ( Figure S2, inset) with etching process. The cluster was cha...

l-Dopa conjugated fluorescent gold cluster to cross undisturbed blood brain barrier for early stage imaging and drug delivery.

Fluorescence and diffuse reflectance spectroscopy are powerful tools to differentiate normal and malignant tissue based on the emissions from endogenous fluorophores and diffuse reflection of absorbers such as hemoglobin. However, separate analytical methods are used for the identification of fluorophores and hemoglobin. The estimation of fluorophores and hemoglobin simultaneously using a single technique of autofluorescence spectroscopy is reported, and its diagnostic potential on clinical tissue samples is potentially exploited. Surgically removed brain tissues from patients that are later identified pathologically as astrocytoma, glioma, meningioma, and schwannoma are studied. The emissions from prominent fluorophores collagen, flavin adenine dinucleotide, phospholipids, and porphyrin are analyzed at 320 and 410 nm excitations. The hemoglobin concentration is also calculated from the ratio of fluorescence emissions at 500 and 570 nm. A better classification of normal and tumor tissues is yielded for 410 nm excitation compared to 320 nm when diagnostic algorithm based on linear discriminant analysis is used. The potential of fluorescence spectroscopy as a single entity to evaluate the prominent fluorophores as well as the hemoglobin concentration within normal and tumor brain tissues is emphasized.

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In photodynamic therapy (PDT), photosensitisers (PS) are used along with lasers for the treatment of tumors. The combined effect of photosensitisers and lasers on the wound healing process is studied using delta-aminolevulinic acid (ALA) (5 mg/kg) and hematoporphyrin derivative (HPD) (5 mg/kg) as photosensitisers in the open excision wounds of rats. The lasers used were He-Ne laser (3 J/cm2) and Nd:YAG laser (30 J/cm2). This study is important for understanding the healing process involved after PDT. Open excision wounds treated with He-Ne lasers in animals that received ALA as photosensitiser showed complete wound closure at the earliest by 13 +/- 1 days, and with results obtained for HPD and the combination of lasers with complete closing by 14 +/- 1 days. However, the control group of animals that received ALS or HPD with no laser treatment showed wound healing on the twentieth and eighteenth days with a deviation of one day and two days, respectively. ALA with the combination of Nd:YAG and He-Ne lasers and HPD with He-Ne laser alone does not show quicker wound healing effects. Histopathological results also gave similar results. Tensile strength measurements do not vary significantly from control group to the test group. ALA along with He-Ne laser of HPD along with the combination of He-Ne and low power Nd-YAG lasers are found to be ideal methods for quickening the wound healing process in rat.