Carbon dots (CDots) are generally defined as small carbon nanoparticles (CNPs) with effective surface passivation, for which the classical synthesis is the functionalization of pre-existing CNPs with organic molecules. However, “dot” samples produced by “one-pot” thermal carbonization of organic precursors are also popular in the literature. These carbonization-produced samples may contain nano-carbon domains embedded in organic matters from the precursors that survived the thermal processing, which may be considered and denoted as “nano-carbon/organic hybrids”. Recent experimental evidence indicated that the two different kinds of dot samples are largely divergent in their photo-induced antibacterial functions. In this work, three representative carbonization-produced samples from the precursor of citric acid–oligomeric polyethylenimine mixture with processing conditions of 200 °C for 3 h (CS200), 330 °C for 6 h (CS330), and microwave heating (CS_MT) were compared with the classically synthesized CDots on their photo-induced antiviral activities. The results suggest major divergences in the activities between the different samples. Interestingly, CS_MT also exhibited significant differences between antibacterial and antiviral activities. The mechanistic origins of the divergences were explored, with the results of different antimicrobial activities among the hybrid samples rationalized in terms of the degree of carbonization in the sample production and the different sample structural and morphological characteristics.

This study investigated the antibacterial activities of Se-Al/Zn layered double hydroxide (LDH) and its polycarbazole (PCz) hybrid against Gram-positive Bacillus subtilis and Gram-negative E. coli cells. Antibacterial performances were evaluated using zone of inhibition assays, viable cell counting, and measurement of metabolic activity based on intracellular ATP levels. The collective results showed that both materials exhibited significant antibacterial activity, with PCz–Se–Al/Zn LDH demonstrating enhanced antibacterial activity compared to Se–Al/Zn LDH. Fluorescent live/dead staining and scanning electron microscopy revealed that treatment with either material resulted in loss of metabolic activity and induction of a non-culturable state in bacterial cells, without observable membrane damage or pronounced morphological changes. Possible antibacterial mechanisms of action associated with LDH and PCz–LDH systems are briefly discussed.