## 3 Results and Discussion
### The Dependence of Adsorption Efficiency of a Mixture of ssDNA to GNPs on Incubation Temperature  
Next, we investigated the dependence of the capacity of GNPs for dsDNA on the incubation temperature of the reaction mixture (25, 37, and 45 \({}^{\circ}\)C). Such data should reveal how the adsorption of a stoichiometric mixture of complementary ssDNA occurs and is realized on GNPs: individually or as part of the duplex. To distinguish between processes of adsorption of dsDNA and the competition of individual ssDNA strands with each other, we conducted experiments on the adsorption of each ssDNA (FLn or FTn) paired with a noncomplementary oligonucleotide, T20, under the same conditions. Oligothymidylate T20 by itself has GNP affinity similar to that of R (Figure S3), i.e., T20 should manifest exceptionally competitive behavior when coadsorbed with any of the ssDNA on GNPs.  
Let us analyze the adsorption (on GNPs) of DNAs of the FLn series in a mixture with the R oligonucleotide, which has almost the same affinity for GNPs as the F oligonucleotide does. For duplexes F*-R and FL*-R, two significantly different binding modes are seen at 25 and 45 \({}^{\circ}\)C (gray and red solid bars in Figure 5A). Duplexes FL2*-R and FL4*-R manifested the same binding mode at all temperatures (green and blue solid bars in Figure 5A). Consequently, the adsorption of dsDNA via a long high-affinity albeit structured \"anchor\" is more favorable at all temperatures as compared to all other adsorption modes. R* paired with any DNA of the L series showed a tendency for increased capacity with increasing temperature (Figure 5C). By contrast, the capacity for T20* in the presence of DNA of the L series either diminished or remained at the same level with increasing temperature (Figure 5E). Namely, under competitive conditions, lower-affinity T20 is inferior to higher-affinity DNAs of the L series. Because T20 is a homosequence, preferential adsorption of any of its regions can be ruled out, and we observed the same magnitude of adsorption at all temperatures. Capacity values of mixtures with T20* did not exceed those for R* under the corresponding conditions (Figure 5C,E). This finding can be explained by partial formation of a duplex between R and DNA of the L series, with this process bringing a greater number of R molecules to the surface of GNPs.  
For oligonucleotide pairs (FTn* and R), similar capacity values were observed regardless of incubation temperature (Figure 5B, e.g., 21 molecules of FT2*-R per GNP at 25, 37, and 45 \({}^{\circ}\)C: green striped bars), in agreement with previously published data [4]. Capacity values of R* in mixtures with DNA of the FT series increased with increasing temperature (Figure 5D), i.e., partial duplex formation takes place, as in the case of FLn-R* (Figure 5E). Note that FT4-R* is adsorbed almost two times more (Figure 5D) as compared to mixture FL4-R* (Figure 5C) at both 25 and 45 \({}^{\circ}\)C. This result reflects more favorable and/or faster adsorption of the shorter and higher-affinity R compared to FT4 (in contrast to the ratio of gold affinity levels in the FL4-R pair) [43]. The substitution of FLn with FTn resulted in a significant increase in the adsorption of T20*, thereby reflecting a difference in the affinity between the L and T motifs, which allows more T20 molecules to be adsorbed during competition with lower-affinity FTn (Figure 5E,F).  
At the same time, we should highlight the absence of a temperature dependence in the adsorption of T20* in pairs with FTn (Figure 5F) or with FLn (Figure 5F), in contrast to the behavior of R*, whose capacity increases with temperature, thus confirming that the adsorption of complementary DNAs is not exclusively competitive (Figure 5C,D).  
Therefore, it can be concluded that when interacting with GNPs, ssDNA complementary to each other compete with each other, while some of them form a duplex, which is also adsorbed on GNPs.