Laravel 5.2 Blade iterate inside a "class attribute" - php

Question

im developing a blog where all post can have more than one categories, and after I want those categories to be the class attribute from a div because im using data-filters to show those post that you select from the categories menu and hide those who are not part of the category.
Im using the next code but if you check {{$post->categorias[0]->nombre}} (where categorias is the category section to iterate and "nombre" is the name of the categories) only will show the first category and I want to show all the categories that belongs to that post, not only the first one.
#foreach($posts as $post)
<figure class="{{$post->categorias[0]->nombre}}">
<a href="project.html" class="thumb">
#foreach($post->imagenes as $imagen)
<img src="/imagenes/articulos/{{$imagen->url}}" alt="alt"/>
#endforeach
</a>
<figcaption>
{{$post->nombre}}</h3>
{{$post->contenido}}</figcaption>
</figure>
#endforeach
I've already tried to iterate inside class=" - " but didn't work, something like this:
<figure class="#foreach ($post->categorias as $po)
{{$po->nombre}}
#endforeach">
bud didn't work
I will appreciate any help. Thank you

Answer 1

BLADE
#foreach($posts as $key => $post)
<figure class="{{$post->categorias[$key]->nombre}}">
<a href="project.html" class="thumb">
#foreach($post->imagenes as $imagen)
<img src="/imagenes/articulos/{{$imagen->url}}" alt="alt"/>
#endforeach
</a>
<figcaption>
{{$post->nombre}}</h3>
{{$post->contenido}}</figcaption>
</figure>
#endforeach
The $key is the 'counter' to get the right data.

Answer 2

#foreach($posts as $post)
<figure class="#foreach($post->categorias as $key => $po)
{{$post->categorias[$key]->nombre}}#endforeach">
<a href="project.html" class="thumb">
#foreach($post->imagenes as $imagen)
<img src="/imagenes/articulos/{{$imagen->url}}" alt="alt"/>
#endforeach
</a>
<figcaption>
{{$post->nombre}}</h3>
{{$post->contenido}}</figcaption>
</figure>
#endforeach
Thanks to #djl for the help :)