DNA is the primary target of many anticancer drugs involved in important intercellular processes, especially in transcriptional regulation, and histone is known to inhibit gene expression. Small molecules can bind to histone-DNA and impair the cell division, growth, inhibition, and apoptosis in cancer cells. In this research, the interaction of a histone H1-calf thymus DNA (ct DNA) complex and propyl acridone (PA) was investigated in Tris-HCl buffer, pH 6.8, using multi-spectroscopic, viscosity, and molecular modeling techniques. The Stern Volmer plot of the (H1-ct DNA) PA complex demonstrated two sets of binding sites with various binding affinities at three different temperatures. Thermodynamic parameters (ΔH° < 0 and ΔS° < 0) indicated that hydrogen bonds and van der Waals forces played the main roles in the binding of the drug to H1-ct DNA. The interaction between PA and ct DNA as well as (H1-ct-DNA) in the presence of acridine orange and ethidium bromide showed two different interaction behaviors in ternary systems. According to results from UV absorption spectroscopy and melting temperature (Tm) measurements, the binding mode of PA with ct DNA and the (H1-ct DNA) complex was indicative of an intercalative binding for the binary system and of both intercalative with groove binding with molecular fraction for the ternary system. Furthermore, the PA-induced detectable changes in the circular dichroism spectrum of ct DNA as well as changes in its viscosity. All of the experimental results proved that the intercalative binding between PA and ct DNA as well as the (H1-ct DNA) complex as binary and ternary systems must be predominant. The results obtained from experimental data were in good agreement with molecular modeling with regard to the determination of the binding site of PA to ct DNA in the absence and presence of histone H1.

Loop-mediated isothermal amplification is a promising candidate for the rapid detection of Mycobacterium tuberculosis. However, the high potential for carry-over contamination is the main obstacle to its routine use. Here, a closed tube LAMP was intended for the visual detection of Mtb to compare turbidimetric and two more favorable colorimetric methods using calcein and hydroxy naphthol blue (HNB). Additionally, a less studied dye (i.e., eriochrome black T (EBT)) was optimized in detail in the reaction for the first time. Mtb purified DNA and 30 clinical specimens were used to respectively determine the analytical and diagnostic sensitivities of each method. The turbidimetric method resulted in the best analytical sensitivity (100 fg DNA/reaction), diagnostic sensitivity and specificity (100%), and time-to-positivity of the test (15 min). However, this method is highly prone to subjective error in reading the results. Moreover, HNB-, calcein-, and EBT-LAMP could respectively detect 100 fg, 1 pg, and 1 pg DNA/reaction (the analytical sensitivities) in 30, 15, and 30 min, while the diagnostic sensitivity and specificity were respectively 93.3% and 100% for them all. Interestingly, EBT-LAMP showed the lowest potential for subjective error in reading the results. This report helps judiciously choose the most appropriate visual method, taking a step forward toward the field applicability of LAMP for the detection of Mtb, particularly in resource-limited settings.