  The electronic structure of monolayer MoS$_2$ nanoribbons and quantum dots
have been investigated by means of an effective $\mathbf{k}\cdot \mathbf{p}$
two-band model. Both systems with borders exhibit states spatially localized on
the edges and with energies lying in the band gap. We show that the conduction
and valence band curvatures determine the presence/absence of these states
whose origin has been related to the marginal topological properties of the
MoS$_2$ single-valley Hamiltonian.
