Browsing by Author "Gunaydin, G."

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Open Access
A bifunctional photosensitizer for enhanced fractional photodynamic therapy: singlet oxygen generation in the presence and absence of light
(Wiley-VCH Verlag, 2016) Turan, I. S.; Yildiz, D.; Turksoy, A.; Gunaydin, G.; Akkaya, E. U.
The photosensitized generation of singlet oxygen within tumor tissues during photodynamic therapy (PDT) is self-limiting, as the already low oxygen concentrations within tumors is further diminished during the process. In certain applications, to minimize photoinduced hypoxia the light is introduced intermittently (fractional PDT) to allow time for the replenishment of cellular oxygen. This condition extends the time required for effective therapy. Herein, we demonstrated that a photosensitizer with an additional 2-pyridone module for trapping singlet oxygen would be useful in fractional PDT. Thus, in the light cycle, the endoperoxide of 2-pyridone is generated along with singlet oxygen. In the dark cycle, the endoperoxide undergoes thermal cycloreversion to produce singlet oxygen, regenerating the 2-pyridone module. As a result, the photodynamic process can continue in the dark as well as in the light cycles. Cell-culture studies validated this working principle in vitro.
Open Access
Does partner responsiveness predict hedonic and eudaimonic well-being? a 10-year longitudinal study
(Wiley-Blackwell Publishing, Inc., 2016) Selcuk, E.; Gunaydin, G.; Ong, A. D.; Almeida, D. M.
Motivated by attachment theory and recent conceptualizations of perceived partner responsiveness as a core feature of close relationships, the authors examined change in hedonic and eudaimonic well-being over a decade in a sample of more than 2,000 married adults across the United States. Longitudinal analyses revealed that perceived partner responsiveness-the extent to which individuals believe that their partner cares for, appreciates, and understands them-predicted increases in eudaimonic well-being a decade later. These results remained after controlling for initial hedonic and eudaimonic well-being, age, gender, extraversion, neuroticism, and perceived responsiveness of family and friends. Affective reactivity, measured via an 8-day diary protocol in a subset of the sample, partially mediated this longitudinal association. After controlling for covariates, perceived partner responsiveness did not prospectively predict hedonic well-being. These findings are the first to document the long-term benefits of perceived partner responsiveness on eudaimonic well-being.
Open Access
Impressions based on a portrait predict, 1-month later, impressions following a live interaction
(SAGE Publications Inc., 2017) Gunaydin, G.; Selcuk, E.; Zayas, V.
When it comes to person perception, does one “judge a book by its cover?” Perceivers made judgments of liking, and of personality, based on a photograph of an unknown other, and at least 1 month later, made judgments following a face-to-face interaction with the same person. Photograph-based liking judgments predicted interaction-based liking judgments, and, to a lesser extent, photograph-based personality judgments predicted interaction-based personality judgments (except for extraversion). Consistency in liking judgments (1) partly reflected behavioral confirmation (i.e., perceivers with favorable photograph-based judgments behaved more warmly toward the target during the live interaction, which elicited greater target warmth); (2) explained, at least in part, consistency in personality judgments (reflecting a halo effect); and (3) remained robust even after controlling for perceiver effects, target effects, and perceived attractiveness. These findings support the view that even after having “read a book,” one still, to some extent, judges it by its “cover.”
Open Access
Minimal social interactions with strangers predict greater subjective well-being
(Springer, 2021) Gunaydin, G.; Öztekin, Hazal; Karabulut, Deniz Hazal; Salman-Engin, Selin
Past empirical work has repeatedly revealed that positive social interactions including expressing gratitude and socializing are associated with greater happiness. However, this work predominantly focused on prolonged interactions with close relationship partners. Only a few studies demonstrated hedonic benefits of forming social connections with strangers. The present research investigated whether minimal social interactions with strangers—just taking a moment to greet, thank, and express good wishes to strangers—contribute to happiness of individuals who initiate these interactions. Study 1 (N = 856) provided correlational evidence that commuters who reported engaging in minimal positive social interactions with shuttle drivers experienced greater subjective well-being (life satisfaction and positive affect). Moreover, hedonic benefits of positive social interactions went beyond relatively more neutral social interactions, Big-Five personality factors, and age, speaking to the robustness of the effect. Study 2 (N = 265) provided experimental evidence that commuters who greeted, thanked, or expressed good wishes to shuttle drivers experienced greater momentary positive affect than those who did not speak with drivers. These findings add to the burgeoning literature on hedonic benefits of interacting with strangers by showing that even very minimal social interactions with strangers contribute to subjective well-being in everyday life.
Open Access
Molecular demultiplexer as a terminator automaton
(Nature Publishing Group, 2018) Turan, İlke S.; Gunaydin, G.; Ayan, Seylan; Turan, İlke S.
Molecular logic gates are expected to play an important role on the way to information processing therapeutic agents, especially considering the wide variety of physical and chemical responses that they can elicit in response to the inputs applied. Here, we show that a 1:2 demultiplexer based on a Zn2+-terpyridine-Bodipy conjugate with a quenched fluorescent emission, is efficient in photosensitized singlet oxygen generation as inferred from trap compound experiments and cell culture data. However, once the singlet oxygen generated by photosensitization triggers apoptotic response, the Zn2+ complex then interacts with the exposed phosphatidylserine lipids in the external leaflet of the membrane bilayer, autonomously switching off singlet oxygen generation, and simultaneously switching on a bright emission response. This is the confirmatory signal of the cancer cell death by the action of molecular automaton and the confinement of unintended damage by excessive singlet oxygen production.
Open Access
Trait reappraisal predicts affective reactivity to daily positive and negative events
(Frontiers Research Foundation, 2016) Gunaydin, G.; Selcuk, E.; Ong, A. D.
Past research on emotion regulation has provided evidence that cognitive reappraisal predicts reactivity to affective stimuli and challenge tests in laboratory settings. However, little is known about how trait reappraisal might contribute to affective reactivity to everyday positive and negative events. Using a large, life-span sample of adults (N = 1755), the present study addressed this important gap in the literature. Respondents completed a measure of trait reappraisal and reported on their daily experiences of positive and negative events and positive and negative affect for eight consecutive days. Results showed that trait reappraisal predicted lower increases in negative affect in response to daily negative events and lower increases in positive affect in response to daily positive events. These findings advance our understanding of the role of reappraisal in emotion regulation by showing how individual differences in the use of this strategy relate to emotional reactions to both positive and negative events outside the laboratory.