Physiochemical changes, including size, are known to affect gold nanoparticle cellular internalization and treatment efficacy. Here, we report the effect of four sizes of cystine/citric acid-coated confeito-like gold nanoparticles (confeito-AuNPs) (30, 60, 80 and 100nm) on cellular uptake, intracellular localization and photothermal anticancer treatment efficiency in MDA-MB231 breast cancer cells. Cellular uptake is size dependent with the smallest size of confeito-AuNPs (30nm) having the highest cellular internalization via clathrin- and caveolae-mediated endocytosis. However, the other three sizes (60, 80 and 100nm) utilize clathrin-mediated endocytosis for cellular uptake. The intracellular localization of confeito-AuNPs is related to their endocytosis mechanism, where all sizes of confeito-AuNPs were localized highly in the lysosome and mitochondria, while confeito-AuNPs (30nm) gave the highest localization in the endoplasmic reticulum. Similarly, a size-dependent trend was also observed in in vitro photothermal treatment experiments, with the smallest confeito-AuNPs (30nm) giving the highest cell killing rate, whereas the largest size of confeito-AuNPs (100nm) displayed the lowest photothermal efficacy. Its desirable physicochemical characteristics, biocompatible nature and better photothermal efficacy will form the basis for further development of multifunctional confeito-AuNP-based nanotherapeutic applications.
The objective of the study was to quantify and to profile the amino acids content in urine samples. The amino acids content in urine was determined in 162 individuals (62 young non-vegetarians aged 15-45 years, 24 elderly non-vegetarians aged 46-70 years, 40 young vegetarians and 36 elderly vegetarians) by high performance liquid chromatography (HPLC). The most common amino acids detected in the young and elderly individuals on vegetarian and non-vegetarian diets were phenylalanine, threonine, arginine and asparagine, while leucine, aspartic acid and alanine were not found in any urine samples in both groups. Isoleucine was not detected in the urine of vegetarians. The concentrations of the majority of essential amino acids were between 0.10 - 2.00 mgl24hrs except for histidine which had a range of 4.1 - 5.0 mgl24hrs. The concentrations of non-essential amino acids varied. Proline, glycine and tyrosine concentrations were between 0.10 - 1.00 mg/24hrs, while cysteine, glutamine, glutamic acid and cystine concentrations were between 11.0 - 21.0 mg124hrs. Asparagine and hydroxy-proline had a range of 0.10 - 5.00 mg/24hrs, while serine and arginine ranged between 31.0 - 50.0 mg124hrs. Isoleucine and serine were not detected in elderly vegetarians while histidine, glycine, glutamic acid and hydroxy-proline were not detected in elderly non-vegetarians. Isoleucine, glycine and hydroxy proline were detected in young non-vegetarians but not in young vegetarians. The levels of amino acids showed no significant statistical differences between young vegetarians and non-vegetarians as well as between elderly vegetarians and non-vegetarians. Phenylalanine, threonine and trypthophan were commonly detected in the lacto-ovo and lacto vegetarians, while valine, cysteine, arginine and asparagine were commonly detected in vegans. In conclusion, except for isoleucine, general differences were seen in urinary amino acid excretions between vegetarians and non-vegetarians even though the differences were statistically not significant. Therefore lacto-ovo diets could be nutritionally adequate as the nutrients were substituted by dairy or plant products.