Context :

Aims : We have obtained high contrast images of four nearby , faint , and very low mass objects 2MASS J04351455-1414468 , SDSS J044337.61+000205.1 , 2MASS J06085283-2753583 and 2MASS J06524851-5741376 ( here after 2MASS0435-14 , SDSS0443+00 , 2MASS0608-27 and 2MASS0652-57 ) , identified in the field as probable isolated young brown dwarfs .
Our goal was to search for binary companions down to the planetary mass regime .

Methods : We used the NAOS-CONICA adaptive optics instrument ( NACO ) and its unique capability to sense the wavefront in the near-infrared to acquire sharp images of the four systems in K _ { s } , with a field of view of 28 ~ { } ^ { \prime \prime } \times 28 ~ { } ^ { \prime \prime } .
Additional J and L ^ { \prime } imaging and follow-up observations at a second epoch were obtained for 2MASS0652-57 .

Results : With a typical contrast \Delta K _ { s } = 4.0 - 7.0 mag , our observations are sensitive down to the planetary mass regime considering a minimum age of 10 to 120 Myr for these systems .
No additional point sources are detected in the environment of 2MASS0435-14 , SDSS0443+00 and 2MASS0608-27 between 0.1 - 12 ~ { } ^ { \prime \prime } ( i.e about 2 to 250 AU at 20 pc ) .
2MASS0652-57 is resolved as a \sim 230 mas binary .
Follow-up observations reject a background contaminate , resolve the orbital motion of the pair , and confirm with high confidence that the system is physically bound .
The J , K _ { s } and L ^ { \prime } photometry suggest a q \sim 0.7 - 0.8 mass ratio binary with a probable semi-major axis of 5-6 AU .
Among the four systems , 2MASS0652-57 is probably the less constrained in terms of age determination .
Further analysis would be necessary to confirm its youth .
It would then be interesting to determine its orbital and physical properties to derive the system ’ s dynamical mass and to test evolutionary model predictions .

Conclusions :