Well-separated water-soluble carbon dots via gradient chromatography.

Carbon dots (CDs) are strongly fluorescent advanced materials that are promising for applications in bio-imaging, sensors or luminescent displays. One of the most-widely used class of CDs is synthesized via an aqueous, bottom-up technique starting from citric acid (CA) and an amino-precursor. Very high fluorescence quantum yields (QY) are reported for the resulting CDs. The as-synthesized raw suspensions, however, are crude mixtures of many components: bare carbon cores, carbon cores functionalized with fluorophores, freely floating molecular fluorophores, and several other by-products. In this study, we synthesized CDs from CA and amino acid cysteine (Cys) hydrothermally and demonstrate a complete separation of all components by means of two step gradient chromatography. In the first step, the separation was carried out on a normal-pressure preparative silica-gel column to get sufficient amounts of material to investigate structure and optical properties of the collected fractions. This preparative gradient elution method enabled us to separate moderately-fluorescent CDs from freely floating molecular fluorophores, polymeric fluorophores and CDs with built-in fluorophores. Here, we evidenced that amorphous CDs co-exist with crystalline CDs in one and the same suspension and showed that the amount of crystalline CDs increases with the synthesis temperature. In the second step, we turned to high performance liquid chromatography (HPLC) to further improve and optimize the efficiency of purification and automate it. Via HPLC, we were able to well-separate of up to six components. Within this work, we laid the foundation for CD purification with the highest possible purity for aqueous, bottom-up synthesized CDs and quantified the true quantum yield of CDs.

Mixed-methods evaluation of a transition and young adult clinic for kidney transplant recipients.

The aims of the present study were to describe the experiences of kidney transplant patients attending a young adult clinic or a regular adult clinic, to explore similarities and differences between the groups, and to conduct an evaluation of the clinical and psychosocial outcomes of the young adult clinic, by comparing these outcomes to those of the regular adult clinic. A mixed-methods design combining qualitative and quantitative data was used. Empirically validated questionnaires measuring self-determination theory variables, quality of life, and adherence were distributed to all consenting patients attending the YAC (n = 17) and RAC (n = 16). Semi-structured interviews were conducted with a subsample of the first (n = 10) and second group (n = 8), and analyzed using thematic analysis. Clinical outcomes were retrieved from medical records. Descriptive, correlational, and comparative analyses were performed. We found clinically significant differences on tacrolimus blood levels variability, self-reported adherence, and physical quality of life. Small and medium effect sizes were detected. No statistical differences were found. Statistically significant correlations were found between self-determination theory variables and both physical quality of life and different measures of adherence. Four themes characterized patients' experiences: resilience; relational needs and the therapeutic alliance; quest for balance; and quest for normalcy. The young adult clinic seems to meet its initial objectives and to make a difference particularly in the early period post-transition, but over time what matters most for patients is therapeutic alliance. Mental health issues need to be better addressed, and special attention should be paid to youths transplanted in an adult setting.