Evaluating trends in recruitment challenges in vape shop research, e-cigarette product characteristics and use among shop customers from 2019 to 2023: A mixed-methods study.

INTRODUCTION: Brick-and-mortar vape shops specialize in the sale of e-cigarettes and remain a primary source for purchasing emerging e-cigarette products. New regulatory policies have been implemented at local-, state- and federal-level; the retail environment at vape shops and product preferences among vape shop customers shifted accordingly. METHODS: From 2019 to 2023, we collected anonymous interview data from vape shop customers (n=572) from 83 vape shops in Southern California. We aggregated the data by month and treated each month as the unit of analysis to document changes in recruitment efforts among the vape shops in relation to major policy implementations over 4 years. We also examined the systematic fluctuations and trends in customers' e-cigarette product preferences and nicotine content in these products. RESULTS: The monthly average shop-level consent rate was 52.9% (SD=8.7), with an overall decreasing trend over time. It was necessary for our data collection team to approach a greater number of vape shops to obtain consent with implementation of various state and federal tobacco regulations and following COVID-19. We observed an increase in the purchase of disposable products and nicotine concentrations in the products, while the average use frequency remained the same. CONCLUSIONS: Our findings demonstrated that user preferences, product characteristics and challenges in research involving vape shops are closely associated to changes in regulations. We documented a dramatic increase in nicotine concentration in products. Future policies restricting the amount of nicotine in tobacco products at the federal level are necessary to protect consumers from further nicotine addiction. This study provides documentation over time of the drastic increases in nicotine concentration among e-cigarette users as a result of the fluctuations in the product market. Regulating nicotine content in tobacco products could safeguard against further unsafe modifications in e-cigarettes and other types of tobacco products.

Adult harm perceptions, purchase, and use related to synthetic vs. tobacco-derived nicotine vaping products: A mixed-methods study.

Objective: Synthetic nicotine (SN) e-cigarettes emerged on the market as an alternative to tobacco-derived nicotine (TDN) vaping products. It is critical to understand the harm perceptions, purchase, and use of SN vs. TDN e-cigarettes. Methods: From November 2021 to February 2023, we conducted intercept interviews with 263 adult customers at 37 vape shops in Southern California. Self-reported use and harm perceptions towards SN vs TDN e-cigarettes were examined. A qualitative analysis of researcher-obtained photographs of vaping items just purchased by customer participants was conducted. Results: Past 30-day SN e-cigarette use was reported by 44 (16.7 %) customers. Past 30-day SN e-cigarette users vs. non-users reported vaping on more days in the past month (29.3 vs. 26.1 days, p = 0.02). Overall, 23.8 % of participants perceived SN e-cigarettes as less harmful than TDN ones; never-smoking vapers and dual users perceived SN e-cigarettes as less harmful than salt-based TDN e-cigarettes. Among 44 customers who purchased SN products (verified through qualitative analysis of photographs), only 13 (29.6 %) self-reported using SN products in the past month, while 5 (11.4 %) indicated they were not aware of the existence of SN products. Most SN vaping products (71.4 %) displayed a modified "tobacco-free" warning label. Conclusions: Misperceptions about SN e-cigarettes were documented in this study, including the perception that SN is either less or more harmful than TDN. Further, some customers may be unknowingly purchasing and using SN e-cigarettes. Regulating "tobacco-free nicotine" terminology in SN vaping products marketing is suggested. SN product labeling should not imply that SN is safe/safer than TDN.

Still 'Cool': tobacco industry responds to state-wide menthol ban with synthetic coolants.

INTRODUCTION: In December 2022, California (CA) enforced a voter-approved regulation restricting the retail sale of flavoured tobacco products, including menthol cigarettes. Shortly after, new products emerged on the market containing similar blue and green package colours yet with 'non-menthol' descriptors. Using chemical analyses, we measured the content of menthol and 15 other cooling chemicals in Californian cigarettes with 'non-menthol' descriptors and compared concentrations to similar 'menthol'-labelled counterparts available in New York State (NY). METHODS: A convenience sample of 10 brands and types of cigarettes in CA were purchased based on package colours suggesting a cooling effect and/or 'non-menthol' descriptors. The exact brand and type of cigarettes (with menthol descriptors) were purchased in NY. Cigarettes from CA were compared with equivalent cigarettes from NY on package design and colours, cigarette physical characteristics and the presence of cooling additives. RESULTS: Menthol was not detected in any CA cigarette, except for Maverick-green box type, while its presence was confirmed in most NY counterpart products. A synthetic cooling chemical WS-3 was not detected in any NY cigarettes but was detected in four CA brands and types with implied cooling effect, ranging from 1.24±0.04 to 1.97±0.05 mg/cigarette. CONCLUSION: While manufacturers have removed menthol descriptors from CA packaging and the menthol ingredient from cigarettes, synthetic cooling chemicals detected in several CA brands suggest that cooling sensory effects may still be sustained. Policymakers must consider both the chemical ingredients themselves and sensory effects in future regulatory approaches.

Hypothetical flavour ban and intention to vape among vape shop customers: the role of flavour preference and e-cigarette dependence.

INTRODUCTION: E-cigarette users typically initiate vaping with flavoured e-liquids. People who vape flavours tend to underestimate the harm of vaping. We examined the inter-relationship between flavour preference, vaping for cessation purposes, e-cigarette dependence, e-cigarette harm perception and purchase/use intention, given a hypothetical flavour ban. We hypothesised that non-tobacco flavour preference and vaping for cessation would be negatively associated with harm perception of e-cigarettes and intention to continue vaping if a flavour ban occurred and that these effects would be mediated by e-cigarette dependence. METHODS: From July 2019 to March 2020, we conducted intercept interviews with 276 customers at 44 vape shops in California. The predictor variables were flavour preference and vaping for cessation. The outcome variables were harm perception of e-cigarettes and intention to purchase/use, given a hypothetical flavour ban. Multilevel structural equation modelling tested whether e-cigarette dependence mediates the effects of flavour preference on hypothetical continued vaping and purchase. RESULTS: Those who preferred flavours showed significantly lower intention to purchase e-liquids (ß=-0.28, p<0.001) and to continue vaping (ß=-0.17, p=0.001), given a hypothetical flavour ban. Those who vaped for smoking cessation indicated greater intention to purchase e-liquid (ß=0.10, p=0.016) and to continue vaping (ß=0.17, p=0.001), given a hypothetical flavour ban. E-cigarette dependence significantly mediated these effects (ps<0.04). DISCUSSION: Flavour preference was negatively related to intention to continue to vape within a hypothetical flavour ban. Our results also highlight the importance of e-cigarette dependence and use of e-cigarettes as smoking cessation methods. Implications for future flavour bans are discussed.

An Assessment of Vape Shop Products in California before and after Implementation of FDA and State Regulations.

Vape shops specialize in sales of e-cigarettes and related products. This study examines whether vape shops adapted their products and services in response to changes in federal and state policies that affect the tobacco retail environment between 2014-2022. In this multicohort study, four waves of study data were used to examine the trends in products sold in vape shops in Southern California. Items sold were assessed through systematic store product observations and included categories of e-cigarettes, device modification equipment, and other products (e.g., Cannabidiol (CBD), paraphernalia). Descriptive statistics are reported. The availability of disposable devices increased from 18% at Wave 1 to 98% of shops at Wave 4. Pod mods were first observed in 79% of the shops beginning at Wave 3. Device modification drills later become obsolete, from 60% at Wave 1 to 0 by Wave 4; self-service sampling displays declined from 83% of shops to 9%. Vape shops did not carry CBD products until Wave 3 (2017/2018), when 19.0% of shops carried CBD products and 72.9% at Wave 4. Future research should examine how e-cigarette retailers and manufacturers respond to changing state and federal regulations to better understand the implications of regulatory efforts.

Compliance to FDA's elimination of free tobacco product sampling at vape shops.

OBJECTIVE: The 2016 FDA's "Deeming Rule" prohibited free samples of vaping products. The purpose of this study was to investigate compliance with or adaptation to this newly established FDA policy. METHODS: Vape shops were recruited in Southern California between November 2017 and December 2018. Data collectors interviewed 121 vape shop employees who responded to questions pertaining to the sampling protocol at their shop. Nicotine levels used for sampling were also assessed for consideration of future policy adoption. RESULTS: Only 7.4% of shops were non-compliant to federal sampling rules. The remaining shops either: 1) charged a fee for samples (58.7%); 2) deducted the fee from the final purchase price (5.8%); or 3) eliminated product sampling (28.1%). Of the shops that charged for sampling (including membership fees), 94.4% initiated a minimal cost protocol (≤$1) for sampling. Half (50.0%) the shops that allowed sampling offered nicotine-containing samples. CONCLUSION: There was high compliance (92.6%) to the change in policy among vape shops. However, minimal modification of sampling protocol was observed due in part to the lack of specificity on parameters of compliance, which lessened the potential impact of the policy. To further protect consumers, policymakers must develop unambiguous and comprehensive policies to achieve intended results and true compliance. At minimum, future tobacco product sampling policies should consider standardized pricing; alternatively, total elimination of tobacco product sampling is suggested.

Prevalence of disposable pod use and consumer preference for e-cigarette product characteristics among vape shop customers in Southern California: a cross-sectional study.

OBJECTIVES: In February 2020, the US Food and Drug Administration issued a guidance restricting the sales and distribution of cartridge-based e-cigarettes with flavours other than tobacco and menthol. Disposable devices were exempt from this guidance. This study examined the prevalence of disposable pod use and flavour preference compared with refillable pod and other e-cigarette users among vape shop customers. DESIGN: Cross-sectional study. SETTING: In July 2019-March 2020, trained data collectors visited 44 vape shops in California with permission to recruit customers from shop owners. PARTICIPANTS: Intercept interviews with 276 customers were conducted. OUTCOMES AND PROCEDURES: Customers were grouped based on self-reported device type used most often (disposable pod, refillable pod and other e-cigarettes). Groups were compared on self-reported demographics, flavours preferred, daily e-cigarette use, preferred nicotine concentration levels and cigarette use. RESULTS: Of the 276 customers surveyed, 11.2% used disposable pods in the past 30 days. Among disposable pod users, fruit/candy (80.7%), mint (77.4%) and menthol (67.7%) were common preferred flavours, while tobacco flavours were less commonly preferred (19.4%). When compared with refillable pod and other non-pod e-cigarette device users, disposable pod users were younger, used higher nicotine concentration levels, were more likely to prefer mint and menthol flavours and use e-cigarettes as their first product, while less likely to ever use cigarettes and use e-cigarettes daily. DISCUSSION: Despite using higher nicotine levels and preferred menthol/mint flavours more often than users of other devices, disposable pod users reported lower prevalence of lifetime smoking and daily vaping and were younger. Given the current findings, regulations addressing non-tobacco flavours and nicotine concentration in disposable pod devices merit consideration in efforts to reduce vaping in younger adult never smokers.

Longitudinal Tracking of Vape Shop Compliance With State Business Regulations Within Southern California Ethnic Neighborhoods During the COVID-19 Pandemic.

The overall aim of this study is to examine vape shop business operations during COVID-19 among a cohort of 88 vape shops in the Greater Los Angeles area in Southern California, located in ethnically diverse communities. A total of six web- and/or phone-based assessments were conducted over a 12-week period (April 1, 2020-June 10, 2020), extending from the mandated closure of nonessential businesses (Stage 1; Assessments 1-3) to the reopening of nonessential sectors (Stage 2; Assessments 4-6), to evaluate business operations (open and closure statuses). The proportion of vape shops found to be noncompliant with the Governor's executive order (i.e., open) during Stage 1 gradually increased from 54 (61.4%) at Assessment 1 (week of April 1, 2020) to 58 (65.9%) at Assessment 3 (week of April 29, 2020). Moreover, vape shops located in Hispanic/Latino and Korean/Asian communities (vs. those in non-Hispanic White and African American communities) were more likely to stay open both during and after the shutdown at Assessments 1 and 6. More specifically, vape shops located in Hispanic/Latino communities were significantly more likely to offer walk-in service during Assessment 1 (during the shutdown), and vape shops in Hispanic/Latino and Korean/Asian were significantly more likely to offer walk-in service during Assessment 6 (after the re-opening). This study demonstrates high rates of noncompliance with shutdown orders among vape shops located in ethnic communities, thus suggesting higher contextual risk factors of COVID-19 exposure among certain ethnic communities.

Peer Crowd Identification of Young and Early Middle Adulthood Customers at Vape Shops.

Vape shops specialize in the sales of e-cigarettes and other vaping products. In recent studies, young adults who use e-cigarettes have tended to identify with at-risk peer crowds. This is the first study to examine vape shop customers' clientele. Composed primarily of young adults and persons in early middle adulthood, we speculated that a relatively high prevalence of those who appeared to bystanders as radical/extreme (at-risk) customers would be identified as such at these shops. We recruited vape shops throughout Southern California (N = 44 shops), and trained teams of data collectors visited each of the consented vape shops, making note of 451 customers' appearance, including features such as manner of dress, presence of tattoos, and hairstyles. Customers were then coded as either belonging to a conventional, progressive, or radical/extreme crowd based on outward appearance. Of the customers observed, 223 (49%) were rated as appearing to be in the conventional crowd; 169 (38%) were rated as appearing to be in the progressive crowd, and only 59 (13%) were rated as appearing to be in the radical/extreme crowd. The conventional crowd tended to appear older. Clientele may reflect that more conventional young and early middle age adults are tempted to visit vape shops due to perceptions of greater acceptability or safety of e-cigarettes. E-cigarette mass media campaigns aimed at protecting potential vape shop customers from harm may need to depict more conservative-looking characters.

Association between federal and California state policy violation among vape shops and neighbourhood composition in Southern California.

INTRODUCTION: Past studies have documented disparities in regulation compliance among tobacco retailers with respect to ethnic diversity in neighbourhoods. This study investigated the association between compliance with the Food and Drug Administration (FDA) and California state rules and neighbourhood ethnic composition of a vape shop location. METHODS: We recruited 122 vape shops located in 'ethnic enclave' neighbourhoods in Southern California. Trained teams of data collectors visited each of the consented vape shops and coded items in the shops that were visible and on display. Location data for the percentages of ethnic composition for a given city were obtained from the U.S. Census Bureau, American FactFinder. Multilevel logistic regression models examined the relationship between the city-level neighbourhood ethnic composition and vape shop rule violation status: not displaying Ask4ID sign and offering free samples. RESULTS: Vape shops located in neighbourhoods/communities with more white residents were significantly less likely to not display Ask4ID sign (p=0.03) and less likely to offer free sampling (p=0.009), controlling for other neighbourhood ethnic characteristics. DISCUSSION: Greater enforcement for proper signage display is needed for vape shops located in racial/ethnic minority locations to ensure that minors are discouraged from purchasing e-products.

Vape Shop Employees: Do They Act as Smoking Cessation Counselors?

INTRODUCTION: This study examined smoking cessation advice offered by vape shop employees, as well as their perceived awareness of vaping research. AIMS AND METHODS: This cross-sectional study was conducted in 121 vape shops in the Greater Los Angeles area of Southern California in four multiethnic communities (Hispanic/Latino, African American, Korean/Asian, and non-Hispanic White). A 35-minute interview assessed the employee's tobacco product use, perceptions of vaping research, and experience advising customers to quit cigarette smoking. RESULTS: Among 121 vape shop employees surveyed, 106 (88%) reported that they provided smoking cessation advice or counseling to customers. Nearly half (45%) reported having no vaping-related research knowledge, while 30% were aware of provaping studies only. Approximately 85% of employees had quit cigarettes by switching to e-cigarettes instead, whereas 15% were dual users. Only 49% believed that vaping products contribute to nicotine addiction among youth. Those who provided advice on quitting cigarette smoking reported significantly lower knowledge of e-cigarette research than those who did not provide advice (p < .01). CONCLUSIONS: Most vape shop employees provide advice to customers who desire to quit cigarette smoking and initiate electronic cigarette use. However, they report a low level of awareness about e-cigarette research. Future research is warranted to examine the specifics of advice provided by vape shop employees. Training programs for vape shop employees and educational campaigns about evidence-based scientific findings on vaping may be beneficial. IMPLICATIONS: Almost nine out of 10 surveyed vape shop employees offered cigarette smoking cessation advice to their customers, while almost half of the retailers report not being aware of any vaping-related research studies. Providing employees with training on evidence-based cessation advice could help protect customers. Also, training programs for vape shop employees and educational campaigns about the risk of nicotine addiction could potentially increase their motivation to avoid sales to minors and to warn adults about nicotine addiction.

Signs and customer behaviors at vape shops: Multivariate multilevel model analysis.

INTRODUCTION: This study examined vape shop customers' behaviors in relation to shop display practices. We hypothesized that display of signs conveying supportive attitude toward vaping at vape shops would be positively associated with customer purchasing and in-shop vaping behaviors. METHODS: We recruited vape shops throughout Southern California (N = 122). Trained teams of data collectors visited each of the consented vape shops, observed customers' characteristics and behaviors (N = 254) and coded items in the shops that were visible and on display. We conducted a multivariate multilevel analysis to account for the data structure where customers were nested within vape shops. RESULTS: Male customers were more likely to purchase e-liquid at the shop than female customers (p < .001). There were no sex differences vaping at the shop (p = .353). We observed more customers vaping at shops with e-cigarette safety displays (p = .024) and more customers purchasing e-liquid at shops with quit smoking signage (p = .004). Point-of-sale displays were not associated with either customer vaping or purchasing behaviors observed at the shop. Displays of state-regulated and nonregulated (i.e., tobacco industry) age-of-sale compliance signs, Ask4ID and WeCard, were not significantly associated with customer vaping or purchase behaviors. CONCLUSION: Certain display signs present at vape shops might communicate to customers that engaging in certain behaviors (e.g., vaping inside the shops) may be safe or acceptable.

Notes From the Field: Vape Shop Business Operations Compliance in the Wake of COVID-19.

The novel 2019 Coronavirus Disease (COVID-19) pandemic has led to the closing of all but essential businesses in California. However, several nonessential businesses have remained open in Southern California despite the mandated "stay at home" order issued by the governor. As part of an ongoing vape shop project involving 88 participating shops, this study investigated the number of vape shops that remained open amidst the coronavirus outbreak and related mandates. Examination of shop social media websites and telephone calls to shops revealed that 61.4% (n = 54) have remained open, particularly within Korean/Asian and Hispanic/Latino ethnic locations (32 of the 54 shops). Importantly, walk-in service was much higher within Hispanic/Latino locations compared to African American, Korean/Asian, or non-Hispanic White neighborhoods (p = 0.03). It is not known if shops that stayed open were in direct violation of the order, didn't know all the details of the order, or found a loophole in the order and believed that they were an essential business. Better communication between the vape shop industry and public health officials during this pandemic is needed.

Predictors of Vape Shops Going out of Business in Southern California.

OBJECTIVES: Vape shops have proliferated in the United States (US) in recent years. As of May 2016, the US Food and Drug Administration (FDA) asserted its authority to regulate electronic nicotine delivery systems. It is critical to understand how these polices have affected the vape shop industry, as the rise and fall of vape shop proliferation has the potential for influencing public health. METHODS: In this longitudinal study, we examined factors associated with vape shop (N = 77) closure over a 2-1/2-year period in southern California. We assessed predictors of vape shops going out of business using a multivariate logistic regression model. RESULTS: Among 77 vape shops assessed at baseline, 44.2% closed over a 2-1/2-year period. The absence of a "bar type" physical environment (OR = 2.64, 95% CI = 1.12-6.20), poorer shop accessibility (OR = 7.11, 95% CI = 1.17-43.24), fewer reports of qualified personnel (OR = 2.28, 95% CI = 1.12-4.64), less average time spent in shop by customers (OR = 4.8, 95% CI = 1.18-19.60), a narrower e-liquid flavor selection (OR = 6.55, 95% CI = 1.56-27.49), and less vape device diversity (OR = 2.36, 95% C = 1.13-4.91) predicted vape shop closure. CONCLUSIONS: The rise and subsequent decline in vape shops could potentially affect public health. However, there needs to be more research on their association with public health..

A Descriptive Longitudinal Study of Changes in Vape Shop Characteristics and Store Policies in Anticipation of the 2016 FDA Regulations of Tobacco Products, Including E-Cigarettes.

After proposing the "Deeming Rule" in 2014, the U.S. Food and Drug Administration (FDA) began regulating the manufacturing, marketing, and sales of electronic cigarette (e-cigarette) products as tobacco products in 2016. The current study conducted vape shop store observations and surveyed Los Angeles-area shop employees (assessing their beliefs, awareness, and perceptions of e-cigarettes and related FDA regulations) at two time points one year apart to better understand what vape shop retailers would do given FDA's soon-to-be-enacted Deeming Rule. The study also compared retailer beliefs/awareness/actions and store characteristics immediately after the Deeming Rule proposal versus a year after the Rule had been proposed, right before its enactment. Two data collection waves occurred before the Deeming Rule enactment, with Year 1 surveying 77 shops (2014) and Year 2 surveying 61 shops (2015-2016). Between the data collection points, 16 shops had closed. Among the shops that were open at both time points, the majority (95% in Year 1; 74% in Year 2) were aware of some FDA regulations or other policies applying to vape shops. However, overall awareness of FDA regulations and state/local policies governing e-cigarettes significantly decreased from Year 1 to Year 2. At both time points, all shops offered customers free puffs of nicotine-containing e-liquids (prohibited by the then upcoming Deeming Rule). Perceptions of e-cigarette safety also significantly decreased between the years. Exploring vape shop retailer perceptions and store policies (i.e., free puffs/samples displays, perceptions of e-cigarette safety, etc.) over time will help the FDA assess the needs of the vape shop community and develop more effective retailer education campaigns and materials targeted to increase compliance with the newly enacted regulations.

Optimization of RGD-Containing Cyclic Peptides against αvß3 Integrin.

We have previously reported the use of one-bead-one-compound (OBOC) combinatorial technology to develop a disulfide cyclic, Arg-Gly-Asp-containing octapeptide LXW7 (cGRGDdvc), that targets αvß3 integrin with high affinity and specificity. αvß3 integrin is known to be overexpressed in many cancers and in tumor vasculature, and it has been established as a cancer therapeutic target. To further optimize LXW7, we have performed systematic structure-activity relationship studies. On the basis of the results, two highly focused OBOC peptide libraries were designed, synthesized, and screened against αvß3 integrin-transfected K562 cells. One of the best ligands, LXW64, was found to have 6.6-fold higher binding affinity than LXW7, and showed preferential binding to cells expressing αvß3 integrin. In addition to binding strongly to U-87MG glioblastoma cells in vitro, LXW64 also targets U-87MG xenografts implanted in nude mice, indicating that it is an excellent vehicle for the delivery of cytotoxic payload to tumors and tumor blood vessels that overexpress αvß3 integrin. Mol Cancer Ther; 15(2); 232-40. ©2015 AACR.

The use of one-bead one-compound combinatorial library technology to discover high-affinity αvß3 integrin and cancer targeting arginine-glycine-aspartic acid ligands with a built-in handle.

The αvß3 integrin, expressed on the surface of various normal and cancer cells, is involved in numerous physiologic processes such as angiogenesis, apoptosis, and bone resorption. Because this integrin plays a key role in angiogenesis and metastasis of human tumors, αvß3 integrin ligands are of great interest to advances in targeted therapy and cancer imaging. In this report, one-bead one-compound (OBOC) combinatorial libraries containing the arginine-glycine-aspartic acid (RGD) motif were designed and screened against K562 myeloid leukemia cells that had been transfected with the human αvß3 integrin gene. Cyclic peptide LXW7 was identified as a leading ligand with a built-in handle that binds specifically to αvß3 and showed comparable binding affinity (IC(50) = 0.68 ± 0.08 µmol/L) to some of the well-known RGD "head-to-tail" cyclic pentapeptide ligands reported in the literature. The biotinylated form of LXW7 ligand showed similar binding strength as LXW7 against αvß3 integrin, whereas biotinylated RGD cyclopentapeptide ligands revealed a 2- to 8-fold weaker binding affinity than their free forms. LXW7 was able to bind to both U-87MG glioblastoma and A375M melanoma cell lines, both of which express high levels of αvß3 integrin. In vivo and ex vivo optical imaging studies with the biotinylated ligand/streptavidin-Cy5.5 complex in nude mice bearing U-87MG or A375M xenografts revealed preferential uptake of biotinylated LXW7 in tumor. When compared with biotinylated RGD cyclopentapeptide ligands, biotinylated LXW7 showed higher tumor uptake but lower liver uptake.

Structure-activity relationship studies of targeting ligands against breast cancer cells.

A series of LXY3 (1) analogues were designed and synthesized. Their binding affinity was demonstrated using MDA-MB-231 breast cancer cells adherence inhibition assay. Further structure-activity relationship was obtained. Analogue 29 was discovered to have 3.5-fold increase of the binding affinity. Fluorescent microscopy and in vivo and ex vivo imaging studies demonstrated that 29 is an efficient in vivo targeting agent against alpha3 integrin of MDA-MB-231 breast tumor xenograft implant.